Doc #70 — Copper Wire Production

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RECOMMENDED ACTIONS (BY URGENCY)

First months (Phase 1)

1. Include copper in the national asset census (Doc #8). Key data: copper stocks at electrical distributors, plumbing suppliers, scrap metal dealers, and wire/cable manufacturers. Inventory existing copper wire and cable at Nexans (formerly Olex) and any other NZ cable manufacturers.
2. Classify copper wire and cable stocks at manufacturers and distributors as strategic materials. Prevent export, hoarding, or non-essential use.
3. Identify all NZ copper smelting, refining, and wire drawing capability through the skills census. This includes foundries that melt copper or bronze, jewellers with small-scale smelting equipment, cable manufacturers with drawing capability, and motor rewinding shops.
4. Preserve all copper from failed equipment. Issue guidance to electricians and maintenance workers: when a motor, transformer, or electrical installation is decommissioned, the copper must be recovered and returned to the national pool, not discarded or buried.

First year (Phase 1–2)

5. Establish a national copper recycling collection programme. Designate collection points at community depots. Categorise incoming copper by type and contamination level (Section 3).
6. Begin smelting trials at an existing NZ foundry — determine whether available furnace equipment can melt and refine recycled copper to electrical-grade purity. Identify the most capable facility (Section 4).
7. Assess existing wire drawing equipment at NZ cable manufacturers. Determine operational status, die inventory, and capacity.
8. Establish copper allocation priorities (Section 2.3) and a rationing framework for new copper wire.

Years 1–3 (Phase 2)

9. Achieve routine copper smelting from recycled feedstock — target: 50–200 tonnes per year of refined copper rod or billet.
10. Establish copper wire drawing capability producing conductor for transformer rewinding (Doc #69), motor rewinding (Doc #95), and distribution cable.
11. Develop NZ-produced wire drawing dies from tool steel for copper drawing. Copper’s softness (tensile strength 200–250 MPa annealed) means tool steel dies — rather than tungsten carbide — are serviceable, substantially reducing the machining precision and material requirements. Tool steel for die blanks must come from pre-event stocks or from NZ Steel Glenbrook (Doc #89); die geometry is machined in NZ engineering workshops (Doc #91).
12. Begin systematic copper recovery from decommissioned buildings and infrastructure as demolition and renovation occur.
13. Cross-train motor rewinding technicians in copper conductor production to build the workforce pipeline.

Years 3–7 (Phase 3)

14. Scale copper wire production to meet growing demand from transformer and motor rewinding programmes.
15. Develop copper rod continuous casting if demand warrants and equipment can be built.
16. If Tasman trade develops, establish copper as a priority import commodity (Doc #140).
17. Assess NZ historical copper mine reopening feasibility — engineering survey of Kawau Island, Thames/Coromandel, and other historical sites.

Years 7–15 (Phase 4)

18. Achieve steady-state copper wire production from combined recycled and (if available) trade-sourced copper, meeting ongoing replacement demand for transformers, motors, and distribution cable.

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ECONOMIC JUSTIFICATION

The cost of not having copper wire

Copper wire is not a product in itself — it is a prerequisite for maintaining nearly every other electrical and mechanical system in NZ’s recovery economy. Without copper conductor:

• Transformers cannot be rewound (Doc #69). Distribution transformer failure without copper for rewinding means loss of electricity supply to affected areas until copper becomes available. Over 10–20 years, accumulated failures would progressively deenergise rural and suburban NZ.
• Electric motors cannot be rewound (Doc #95). Motor failure without copper for rewinding means loss of water pumps, grain mills, milking machines, workshop machinery, and the hundreds of other motor-driven systems that NZ’s economy depends on.
• New micro-hydro generators cannot be built (Doc #128). NZ’s most feasible energy expansion pathway requires generator windings.
• HF radio equipment cannot be fabricated or repaired (Doc #128). Communications resilience depends on maintaining and expanding HF radio capability.
• Electrical distribution cannot be extended or repaired. As NZ’s population and economic activity shift geographically (northward under nuclear winter, or to new industrial sites), new electrical connections require copper cable.

Investment required

Smelting and refining programme:

• Facility: Existing foundry (no new construction initially), adapted for copper smelting. Upgrade to dedicated copper refining furnace in Phase 2–3.
• Equipment: Furnace lining, crucibles, flux materials, casting moulds — mostly from NZ materials (Section 4).
• Training: 5–10 copper smelting and refining technicians, trained from existing foundry workers and metallurgists. Training period: 3–6 months under experienced supervision.
• Estimated labour: 3–5 person-years to establish capability, plus 5–15 person-years per year of ongoing operation at 50–200 tonnes per year.

Wire drawing programme:

• Facility: Existing cable manufacturing plant (Nexans or equivalent) if operational, or purpose-built drawing workshop.
• Equipment: Drawing machines (existing if available), dies, annealing furnace, lubricant system.
• Training: 5–10 wire drawing operators, trainable from existing cable manufacturing workers or general machinists.
• Estimated labour: 2–5 person-years to establish capability, plus 5–10 person-years per year of ongoing production.

Total programme: approximately 10–30 person-years per year at steady state, supporting an output that enables the transformer, motor, and electrical distribution maintenance programmes across the entire country. Wire drawing and copper smelting require trained technicians, but the skills are trainable within months from existing foundry workers and machinists — these are not scarce specialists competing with other critical programmes, and the workforce can be drawn from NZ’s pool of displaced manufacturing and trades workers.

Comparison with the alternative

The alternative to domestic copper wire production is progressive degradation of NZ’s electrical infrastructure as transformers, motors, and cables fail and cannot be repaired. This is not a sudden failure but a slow accumulation of losses — each unrepairable failure means one more farm without electricity, one more workshop without motor-driven tools, one more community without grid power. Over 10–20 years, the cumulative effect is a substantial reduction in electrified capability in affected areas.

The economic value of maintaining electrification is high. Electricity powers milking sheds, water pumping, refrigeration, grain milling, machine shops, hospitals, communications, and lighting. The person-year investment in copper wire production is justified by the economic activity that continued electrification enables — a 10–30 person-year annual programme sustaining the electrical infrastructure for the entire country.

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1. NZ’S COPPER INVENTORY

1.1 Where NZ’s copper is

NZ imports approximately 15,000–25,000 tonnes of copper and copper products per year under normal conditions — as wire, cable, pipe, sheet, fittings, and embedded in imported machinery and vehicles.⁴ Over decades of accumulation, the total in-country stock has grown to an estimated 300,000–600,000 tonnes. This estimate is uncertain and is based on per-capita copper stock ratios observed in comparable developed countries (typically 100–170 kg per person for countries with NZ’s level of development, applied to NZ’s population of approximately 5.2 million).⁵

This copper is distributed across:

Building wiring (largest single category, estimated 80,000–200,000 tonnes): Every commercial and residential building constructed since the 1950s contains copper wiring for power circuits, lighting circuits, and data cabling. Older buildings may contain less copper (simpler wiring, fewer circuits), while modern commercial buildings contain substantially more (data centres, air conditioning controls, security systems, networked lighting). NZ has approximately 2 million dwellings and hundreds of thousands of commercial structures.⁶

Plumbing (estimated 30,000–80,000 tonnes): Copper pipe for hot and cold water supply was the dominant plumbing material in NZ from the 1950s to the 2000s. More recent construction uses plastic pipe (PEX, CPVC), but the existing stock of copper plumbing in older buildings is substantial. Copper plumbing is among the easier categories to recover because pipe is thick-walled, easily identified, and typically accessible in wall and floor cavities during renovation or demolition.

Electric motors and generators (estimated 30,000–60,000 tonnes): Every electric motor contains copper windings — from the small motors in household appliances (100–500 grams of copper each) to large industrial motors (50–500 kg of copper each) and generators at power stations (tonnes of copper each).⁷ The total across NZ’s millions of motors is substantial but highly dispersed.

Transformers (estimated 20,000–50,000 tonnes): NZ’s grid transformers contain significant copper — a 50 kVA distribution transformer contains 30–60 kg, a large grid transformer contains several tonnes (Doc #69). The total across NZ’s distribution and transmission transformer fleet is a meaningful reserve, but this copper is in active service and should be recovered only when transformers fail beyond repair.⁸

Telecommunications cable (estimated 15,000–40,000 tonnes): NZ’s copper telecommunications network — now largely superseded by fibre optic for new installations — contains substantial copper in twisted-pair cable running from exchanges to premises. Chorus (NZ’s network infrastructure company) operates approximately 70,000–80,000 km of copper local loop cable.⁹ As fibre replacement progresses, the copper telecommunications network becomes a significant recovery resource. Under post-event conditions where fibre optic networks may be maintained (per baseline scenario), the old copper cable becomes available for recycling, though the logistics of recovery from underground ducts and aerial routes are significant.

Vehicles (estimated 10,000–25,000 tonnes): A modern vehicle contains approximately 20–30 kg of copper in its wiring harness, starter motor, alternator, and radiator (if copper-brass). NZ’s fleet of approximately 4.4 million vehicles represents a substantial but dispersed copper source.¹⁰ As vehicles are mothballed and eventually scrapped (Doc #33, Doc #6), copper recovery should be systematic.

Industrial equipment, heat exchangers, and miscellaneous (estimated 20,000–50,000 tonnes): Copper in dairy processing equipment (heat exchangers, vats), brewing equipment, air conditioning systems, solar hot water panels, electronics, coins, decorative items, and general industrial machinery.

Category	Estimated range (tonnes)	Recovery difficulty
Building wiring	80,000–200,000	Medium — requires demolition or renovation access
Plumbing pipe	30,000–80,000	Medium — thick wall, easily identified
Electric motors/generators	30,000–60,000	Low–Medium — motors are discrete, identifiable objects
Transformers	20,000–50,000	Low — but in active service; recover only on failure
Telecommunications cable	15,000–40,000	Medium–High — buried or aerial, distributed
Vehicles	10,000–25,000	Medium — requires vehicle processing
Industrial/miscellaneous	20,000–50,000	Varies widely
Total	~300,000–600,000

1.2 What this stock represents

NZ’s pre-event copper consumption of 15,000–25,000 tonnes per year will not continue. Post-event copper demand is primarily for replacement and repair, not new construction at pre-war scale. Estimated post-event demand depends on the rate of equipment failure and the scope of new construction, but might be in the range of 500–3,000 tonnes per year, declining over time as the most failure-prone items are replaced and demand stabilises.¹¹

At that consumption rate, the installed copper stock represents decades to centuries of supply — if it can be recovered. The constraint is not the total quantity of copper in NZ but the rate at which it can be collected, smelted, refined, and drawn into usable wire. The production infrastructure described in this document is what determines whether NZ’s copper stock is accessible or locked in place.

1.3 What NZ does not have

Primary copper ore deposits of commercial scale. NZ has historical copper mining — most notably at Kawau Island (Hauraki Gulf), Thames/Coromandel, and small deposits in Nelson and Otago — but these were small operations that closed in the 19th or early 20th century when the easily accessible ore was exhausted.¹² Some copper mineralisation exists in the Coromandel volcanic zone and in the Dun Mountain ophiolite belt (Nelson/Marlborough), but no deposit has been identified that would support meaningful modern-scale mining.¹³

Copper smelting or refining infrastructure. NZ has no copper smelter. Copper refining to electrical grade (99.9%+ purity) requires either electrolytic refining or very careful fire refining — neither of which currently operates in NZ at any scale. Building this capability is the central technical challenge of this document.

Copper wire drawing infrastructure at scale. Nexans NZ (formerly Olex NZ, formerly BICC) has cable manufacturing operations that include wire drawing, but the current status, scale, and operational readiness of this equipment requires verification.¹⁴ If this equipment is functional, it represents NZ’s most important existing copper processing asset. If it is not, wire drawing capability must be built largely from scratch.

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2. COPPER DEMAND UNDER RECOVERY CONDITIONS

2.1 What copper is needed for

Post-event copper demand falls into several categories, ranked by priority:

Priority 1 — Grid maintenance:

• Transformer rewinding (Doc #69): 30–60 kg per distribution transformer. If NZ rewinds 50–200 transformers per year, copper demand is 1.5–12 tonnes per year for this application alone.
• Distribution cable repair and extension: Repairing storm-damaged lines, extending service to relocated communities or new industrial sites.
• Generator rewinding: Power station generators contain large copper windings that will eventually need replacement.

Priority 2 — Motor rewinding:

• Motor rewinding (Doc #95): NZ’s industrial and agricultural economy runs on electric motors. A typical 5 kW motor contains 3–8 kg of copper. A large pump motor may contain 50–200 kg. Annual motor rewinding demand depends on the failure rate across NZ’s motor fleet — this is uncertain but could require 50–500 tonnes of copper per year.¹⁵

Priority 3 — New construction and expansion:

• Micro-hydro generators (Doc #128): Each unit requires 10–50 kg of copper for windings, depending on capacity.
• HF radio equipment (Doc #128): Antenna wire, transformer wire, coil wire.
• Building wiring for new construction or rewiring of existing buildings.
• General electrical and industrial use.

2.2 Demand estimate

A rough estimate of annual copper demand under recovery conditions:

Application	Estimated tonnes/year	Phase
Transformer rewinding	2–12	2–4
Motor rewinding	50–500	2–4
Distribution cable	20–100	2–4
Micro-hydro generators	5–50	3–4
Building wiring	10–100	2–4
HF radio and communications	1–5	2–3
General industrial	10–50	2–4
Total	~100–800

This is a rough estimate. The actual demand depends on infrastructure failure rates, the pace of new construction, and how aggressively NZ expands its electrical system. The wide range reflects genuine uncertainty — at the low end, NZ is maintaining systems conservatively; at the high end, it is actively expanding capacity.

2.3 Allocation priorities

Under scarcity, copper must be allocated by contribution to recovery:

1. Grid transformers — loss of a transformer means loss of supply to an area until rewinding copper is available
2. Water supply and essential service motors — loss of a pump motor means loss of water supply
3. Agricultural motors — milking machines, grain mills, feed processing
4. Micro-hydro generators — expanding NZ’s distributed generation capability
5. Communications equipment — HF radio, telephone system maintenance
6. General industrial motors and equipment — machine shops, workshops
7. Building wiring — lowest priority unless for essential services

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3. COPPER RECYCLING AND COLLECTION

3.1 Source categories

Recycled copper comes in varying quality, and the processing effort depends on what the copper is mixed with:

Category 1 — Clean copper (minimal processing needed):

• Copper pipe and tube (plumbing) — pure copper, easily melted
• Heavy copper bus bar and sheet — from electrical switchboards, busbars
• Clean copper wire stripped of insulation — requires insulation removal but the copper itself is high quality
• Copper windings from motors and transformers, after insulation removal

Category 2 — Contaminated copper (requires sorting and cleaning):

• Insulated wire and cable — copper must be separated from PVC, rubber, or cross-linked polyethylene insulation. Burning off insulation is effective but produces toxic fumes (particularly from PVC, which releases hydrochloric acid gas) and should be done only in controlled conditions with adequate ventilation or, better, by mechanical stripping.¹⁶
• Copper alloys (brass, bronze) — copper alloyed with zinc, tin, or other metals. Must be segregated from pure copper sources. Brass and bronze are useful in their own right (bearings, fittings, marine hardware) but cannot be used for electrical conductor without de-alloying, which is not practical at small scale.
• Vehicle wiring harnesses — thin wire, often tinned, with extensive insulation. Labour-intensive to strip.

Category 3 — Mixed scrap (significant processing):

• Electronic circuit boards — contain copper traces and foil, mixed with fibreglass, solder (tin-lead), and components. Copper recovery from circuit boards is possible by acid leaching or smelting but is complex and produces hazardous waste.¹⁷
• Telecommunications cable — multiple pairs of thin copper wire with paper or plastic insulation, contained in lead or plastic sheath. Bulk recovery is feasible but labour-intensive.
• Small copper items embedded in other materials — copper fittings brazed into steel, copper tracks on circuit boards, copper heat exchanger tubes rolled into steel tubesheets.

3.2 Collection logistics

Copper recovery under post-event conditions will be driven by two streams:

Opportunistic recovery (ongoing): As buildings are demolished, vehicles scrapped, equipment decommissioned, and infrastructure modified, copper is recovered as a byproduct. This requires that all workers involved in demolition, vehicle processing, and equipment maintenance are trained to recognise and segregate copper, and that collection depots are established where copper can be deposited. The key risk is that copper is discarded or mixed with general waste if workers are not trained and incentivised to recover it.

Directed salvage (as needed): When copper demand exceeds opportunistic supply, directed salvage operations — deliberately stripping copper from buildings, cable routes, or equipment that would not otherwise be touched — become necessary. This is more labour-intensive per tonne of copper recovered but provides controlled supply. Priority targets for directed salvage include:

• Decommissioned buildings in areas where population has relocated
• Abandoned copper telecommunications cable in areas served by fibre
• Vehicle wrecking yards where large numbers of scrapped vehicles have accumulated
• Redundant industrial equipment

3.3 Insulation removal

Most copper recovery involves separating copper from insulation — plastic, rubber, paper, enamel, or varnish. Methods:

Mechanical stripping (preferred): Wire stripping machines — essentially adjustable blade sets that cut through insulation without damaging the copper — exist at NZ scrap metal dealers and electricians’ workshops. For large cable, a cable stripping machine feeds cable through rotating blades. For small wire, hand-held strippers work. Mechanical stripping is slow for thin wire but avoids the hazards of thermal stripping.

Thermal stripping (for large volumes, with caution): Heating insulated wire to approximately 400–500°C burns off organic insulation (PVC, rubber, enamel). This can be done in a furnace or kiln with exhaust ventilation. PVC insulation releases hydrogen chloride gas (toxic and corrosive) when burned. Rubber produces sulfur dioxide. Both require that the process is done outdoors or with forced ventilation, and ideally with exhaust gas scrubbing (lime wash to neutralise acid gases).¹⁸ Thermal stripping is faster than mechanical stripping for bulk processing of thin wire and motor windings.

Chemical stripping: Solvent-based removal of enamel insulation (using methylene chloride or similar solvents) is effective for fine wire from motor and transformer windings but requires imported solvents. Concentrated sulfuric acid dissolves enamel but is hazardous to handle. Caustic soda (sodium hydroxide) solution dissolves some insulation types. Chemical stripping is a fallback for high-value fine wire where mechanical and thermal methods are impractical.

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4. COPPER SMELTING AND REFINING

4.1 Why purity matters

Copper for electrical conductor must be high purity. Electrical-grade copper (ETP copper, C11000) is 99.90% or higher copper content.¹⁹ Even small amounts of impurities — particularly arsenic, antimony, bismuth, and iron — dramatically increase electrical resistivity. As little as 0.04–0.05% iron in copper reduces conductivity by approximately 15–25% (equivalent to a 20–33% increase in resistivity).²⁰ This matters for transformer and motor windings because increased resistivity means more heat generation (I²R losses), lower efficiency, higher operating temperature, and shorter life.

For some applications — grounding conductors, low-voltage power cable, and mechanical uses — lower purity copper (99.5–99.8%) is acceptable. But for transformer windings (Doc #69), motor windings (Doc #95), and fine signal wire for HF radio (Doc #128), high purity is important.

4.2 Fire refining [A]

Fire refining is the process of melting impure copper and removing impurities through controlled oxidation and reduction — a technology that has been practised for thousands of years. It requires no imported reagents: the necessary materials are silica sand (available throughout NZ as flux), green hardwood (for poling), and a furnace capable of reaching 1,100°C (existing NZ foundry equipment or a charcoal-fired crucible furnace).

The process:

1. Charge the furnace with sorted copper scrap (Category 1 material — clean copper pipe, stripped wire, clean windings). The furnace must reach approximately 1,100°C, above copper’s melting point of 1,085°C. A crucible furnace, reverberatory furnace, or small electric arc furnace will serve.²¹

2. Melt. Once the charge is molten, slag (iron oxides, silica, aluminium oxide) floats to the surface and is skimmed off. Adding a flux — typically silica sand (available throughout NZ) mixed with borax (if available from pre-event stocks) or limestone — helps dissolve impurities into the slag. Silica flux is essential for removing iron: it reacts with iron oxide to form iron silicate slag (fayalite, Fe₂SiO₄) which is fluid and easily removed.²²

3. Oxidise. Blow air through the molten copper (using a pipe or tuyere submerged in the melt, or by bubbling compressed air through it). Oxygen reacts with impurities — sulfur, iron, zinc, lead, tin — oxidising them. The oxides either dissolve in the slag or evaporate. This step removes most metallic impurities except those that are nobler than copper (silver, gold — which remain in the copper and are acceptable for electrical purposes).²³

4. Pole (reduce). After oxidation, the copper contains dissolved oxygen (as cuprous oxide, Cu₂O) which makes it brittle and unsuitable for wire drawing. To remove the oxygen, submerge a green wood pole (any NZ hardwood will serve — manuka, pohutukawa, or eucalyptus) in the molten copper. The wood releases hydrocarbon gases that reduce the dissolved oxygen. This process — called “poling” — was the standard copper refining technique from the Bronze Age until the 20th century. The pole is consumed and must be replaced periodically. Poling continues until a sample of the copper, when solidified, shows a flat or slightly concave surface (indicating correct oxygen level — over-oxidised copper shows a convex surface; over-reduced copper shows a sunken surface with gas holes).²⁴

5. Cast. Pour the refined copper into moulds to produce billets, rod, or ingots for subsequent processing.

Purity achievable by fire refining: Careful fire refining can produce copper of approximately 99.5–99.8% purity.²⁵ This is adequate for many electrical applications but falls short of the 99.9%+ standard for transformer-grade conductor. Whether fire-refined copper is adequate for distribution transformer rewinding depends on the specific impurities present — some (silver) are harmless, others (iron, arsenic) are very damaging. Testing the conductivity of each batch (Section 4.4) is essential.

4.3 Electrolytic refining

For applications requiring higher purity (99.9%+ for transformer and motor windings), electrolytic refining is the standard industrial method. Fire-refined copper is cast into anodes, which are suspended in an acidified copper sulfate electrolyte solution. A DC electrical current is passed through the solution, dissolving copper from the impure anode and depositing pure copper on a cathode. Impurities either dissolve in the electrolyte (and are removed by periodic solution purification) or fall to the bottom of the tank as insoluble “anode slime.”²⁶

Requirements for electrolytic refining:

• DC power supply: NZ’s grid provides AC; a rectifier (transformer + diode bridge) converts to DC. Large-scale electrolytic refining uses substantial current at low voltage — typically 0.2–0.4 V per cell, with cells connected in series to match available supply voltage. A small refining operation (1–2 tonnes per day capacity) might require 5,000–20,000 amperes at 5–50 V DC.²⁷
• Electrolyte: Copper sulfate dissolved in dilute sulfuric acid (approximately 40–50 g/L copper, 150–200 g/L sulfuric acid). Copper sulfate can be produced by dissolving copper in sulfuric acid. Sulfuric acid is the constraint — NZ does not currently produce it, though production from NZ geothermal sulfur sources is feasible (Doc #113). Without domestically produced sulfuric acid, electrolytic refining is limited to whatever acid stocks exist in NZ at the time of the event.²⁸
• Tanks: Acid-resistant tanks (lead-lined timber, concrete with acid-resistant coating, or high-density polyethylene). Lead-lined tanks were the historical standard and are within NZ’s capability. Lining a timber or concrete tank with lead sheet (salvaged from roofing, batteries, or cable sheathing) produces a serviceable electrolytic cell.
• Anode and cathode materials: Anodes are cast from fire-refined copper. Cathodes are thin starting sheets of pure copper (initially from pre-event pure copper stock; subsequently from the first cathodes produced). Cathode copper deposited by electrolytic refining is typically 99.95–99.99% pure — more than adequate for any electrical application.²⁹

Feasibility assessment [B]: Electrolytic refining uses well-understood chemistry and the equipment is buildable from NZ materials (tanks, lead lining, rectifiers), but it requires several precursor capabilities: sulfuric acid production (Doc #113, itself dependent on geothermal sulfur extraction and acid plant construction), DC rectifier fabrication or salvage, and lead sheet for tank lining. The binding constraint is sulfuric acid — both the initial charge (1.5–2 tonnes for a small refinery) and ongoing makeup supply.³⁰ If NZ develops sulfuric acid production, electrolytic copper refining becomes feasible. If acid production is not available, fire refining is the fallback, with conductivity testing to verify that each batch meets the minimum standard for its intended application.

4.4 Conductivity testing

Every batch of refined copper should be tested for electrical conductivity before being drawn into wire for electrical use. The test requires only basic electrical measurement equipment:

1. Cast or draw a sample of the refined copper into a wire of known length and cross-section.
2. Measure its electrical resistance using a Wheatstone bridge or milliohmmeter (instruments available in NZ electrical workshops and labs).
3. Calculate resistivity and compare to the standard for pure copper: 1.724 × 10⁻⁸ Ω·m at 20°C (defined as 100% IACS — International Annealed Copper Standard).³¹
4. Copper at 97% IACS or higher is acceptable for most electrical applications. Copper below 95% IACS should be reserved for non-electrical uses (plumbing, heat exchangers, grounding conductors) or re-refined.

This test is non-destructive (the sample can be re-melted) and can be performed with basic electrical test equipment that NZ has in abundance.

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5. FURNACE OPTIONS FOR COPPER SMELTING

5.1 Existing NZ foundry capability

NZ has foundry capability — several foundries operate or have recently operated, casting iron, steel, bronze, and aluminium for industrial, marine, and agricultural applications.³² Whether any NZ foundry currently melts copper in significant quantities is uncertain and should be verified through the skills census.

Key foundries and potential copper smelting sites include: Metalform (Christchurch, iron and steel casting), Pacific Steel Group operations (Auckland), Waikato Foundries (Hamilton area), and various marine and agricultural foundries in regional centres including Nelson, Dunedin, and Whanganui. The NZ Foundry Association membership list is the reference for a complete current inventory. The specific furnace types, capacities, current operational status, and suitability for copper melting must be established through the asset census (Doc #8) — this list is indicative only and should not be used for planning without verification.³³

5.2 Crucible furnace (simplest option) [A]

A crucible furnace — a refractory-lined chamber in which a crucible (a pot made of graphite-clay, silicon carbide, or steel) containing the copper charge is heated by coke, charcoal, gas, or electricity — is the simplest and most readily achievable copper smelting option.³⁴

Characteristics:

• Batch size: 10–100 kg per heat, depending on crucible size
• Heat time: 1–3 hours to reach copper melting temperature
• Fuel: Electric resistance heating is most controllable and cleanest; charcoal (Doc #102) is the domestic alternative to electric heating
• NZ capability: Crucible furnaces exist at NZ foundries and can be fabricated from fire brick and refractory cement. Fire brick (high-alumina refractory) is stocked by NZ industrial suppliers and is used in NZ’s existing foundry and kiln industry; stocks and local availability should be confirmed through the asset census (Doc #8).³⁵ Crucibles can be procured from existing stocks or fabricated from silicon carbide or high-temperature steel (though steel crucibles have shorter life when melting copper due to iron contamination of the melt — a graphite-clay or silicon carbide crucible is preferred).³⁶

Production rate: A single crucible furnace operated by 2–3 workers could produce approximately 100–300 kg of refined copper per day, assuming 2–4 heats of 30–100 kg each at a cycle time of 3–5 hours per heat (including charge, melt, skim, oxidise, pole, and cast). At 250 working days per year this yields approximately 25–75 tonnes per year. This is a modest but meaningful output capable of supporting NZ’s transformer and motor rewinding demand in Phase 2, provided scrap feedstock is available and sorted.³⁷

5.3 Electric induction furnace [B]

If available, an electric induction furnace is the preferred option for copper melting. Induction furnaces heat the metal directly through electromagnetic induction — a high-frequency alternating current in a coil surrounding the crucible induces eddy currents in the metal charge, which heat it. The advantages over crucible furnaces are faster melting, more precise temperature control, and less contamination of the melt.³⁸

NZ’s existing induction furnaces are found at foundries and may include units suitable for copper melting. An induction furnace designed for iron or steel can melt copper (copper melts at a lower temperature than iron), though the operating frequency and power settings may need adjustment.

NZ production pathway: If an existing induction furnace is available and operational, it should be the primary copper smelting unit. If not, a purpose-built induction furnace for copper is within NZ’s electrical engineering capability — the furnace coil is a copper water-cooled tube wound around a refractory crucible, powered by a medium-frequency power supply. Building the power supply (an inverter converting grid-frequency 50 Hz AC to 1–10 kHz for a small furnace) is within the capability of NZ’s power electronics technicians, though it requires components (thyristors or IGBTs, capacitors) from pre-event stocks.³⁹

5.4 Fuel and energy requirements

Melting copper requires significant energy — the enthalpy of fusion for copper is approximately 205 kJ/kg, plus the heat required to bring it from room temperature to 1,085°C (approximately 350 kJ/kg), plus furnace losses. In practice, a well-operated crucible furnace requires approximately 1.5–3.0 kWh of electrical energy per kg of copper melted, or approximately 3–6 kg of charcoal per kg of copper (charcoal has much higher losses due to combustion inefficiency and heat escaping the furnace).⁴⁰

At 50–200 tonnes per year production, the electrical energy requirement is approximately 75,000–600,000 kWh per year. For reference, a single NZ household consumes approximately 7,000–8,000 kWh per year.⁴¹ The energy requirement for copper smelting at this scale is therefore equivalent to approximately 10–80 households — significant but manageable within NZ’s grid capacity.

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6. ROD CASTING AND WIRE DRAWING

6.1 From refined copper to rod

Refined copper must be formed into rod before it can be drawn into wire. Two methods:

Gravity casting into moulds: The simplest approach. Pour molten refined copper into long, narrow moulds (iron or steel moulds, approximately 10–20 mm square cross-section) to produce bar stock. After solidification, the bar is worked (hammered, rolled, or swaged) to reduce cross-section and improve grain structure, then fed into the wire drawing process. This is the historical method and works for small-scale production. Mould fabrication is within NZ’s foundry capability.⁴²

Continuous casting: The modern industrial method. Molten copper is poured into a water-cooled mould and withdrawn continuously as a solid rod. This produces rod with better internal structure (fewer voids, more consistent grain) and higher throughput than gravity casting. Building a continuous casting setup is more complex but NZ has the engineering capability if demand warrants. The essential components are a tundish (a small holding vessel feeding the mould), a water-cooled graphite or copper mould, and a withdrawal mechanism. These can be fabricated from NZ materials with engineering workshop support (Doc #91).⁴³

Rod diameter: The starting diameter for wire drawing is typically 8–12 mm. This can be achieved either by casting directly to near this size (in small moulds) or by casting larger billets and hot-rolling or swaging them down.

6.2 Wire drawing for copper [B]

Wire drawing for copper follows the same principles as steel wire drawing (described in Doc #52 and Doc #102) but requires lower forces because copper is much softer and more ductile than steel:

• Copper’s tensile strength (annealed) is approximately 200–250 MPa, versus 400–700 MPa for low-carbon steel wire. This means lower drawing forces, less die wear, and more reduction per pass is possible.
• Copper can typically be reduced 90–95% in cross-sectional area before annealing is required, compared to 75–85% for steel. This means fewer drawing passes and fewer intermediate annealing steps.⁴⁴
• Drawing dies for copper can be made from tool steel (adequate due to copper’s softness) rather than requiring tungsten carbide. Die life when drawing copper with tool steel dies is substantially longer than when drawing steel — typically 50–200 tonnes of wire drawn per die before regrinding is required, compared to a few tonnes for steel-on-steel.⁴⁵ Tungsten carbide dies, if salvageable from pre-event cable-drawing equipment, should be preserved for fine wire sizes where die wear rate is highest.

The drawing process for copper wire:

1. Anneal the rod. Heat the cast copper rod to approximately 400–600°C to soften it (recrystallisation anneal). This can be done in a simple furnace or, for small quantities, with a torch. Cool in air.
2. Point the rod end. Hammer, swage, or grind the end to a taper that will fit through the first die.
3. Draw through successive dies. Each die reduces the diameter by approximately 20–35% (area reduction). For copper, a typical drawing sequence from 10 mm rod to 2 mm wire might require 8–10 passes through progressively smaller dies.
4. Intermediate annealing. After approximately 4–6 drawing passes (when the copper has work-hardened to the point where further drawing risks cracking), anneal at 400–600°C to restore ductility. For copper, annealing can be done in air (unlike steel, where scale formation is a concern — copper oxide formed during annealing is thin and does not significantly affect subsequent drawing).
5. Final draw to target diameter. The last pass(es) bring the wire to the required finished diameter.
6. Final anneal (for soft-temper wire). Most electrical applications require soft (annealed) copper wire for flexibility and ease of winding. A final anneal at 400–600°C produces fully softened wire.

Drawing lubricant for copper: Tallow, tallow-soap emulsions, or calcium stearate work for copper wire drawing. Commercial copper drawing lubricants are synthetic oil-based emulsions that provide superior surface finish (surface roughness Ra typically 0.2–0.5 micrometres). NZ-produced tallow-based lubricants (Doc #34) produce rougher surface finish (estimated Ra 0.5–1.5 micrometres) and may leave organic residues that interfere with enamel adhesion.⁴⁶ For general power cable and grounding wire, tallow lubricant is adequate. For transformer-grade wire where surface quality affects insulation integrity, filtered tallow or lanolin-based lubricant (Doc #34) should be used, and the wire should be cleaned before enamel coating.

6.3 Insulation for copper wire

Bare copper wire serves some applications (grounding conductors, antenna wire for HF radio), but most uses require insulation:

Enamel-coated wire (magnet wire): The standard winding wire for transformers and motors. Bare copper wire is coated with a thin layer of insulating enamel (polyester, polyurethane, or polyimide varnish) by passing it through a varnish bath and then through a curing oven. The enamel layer is typically 0.02–0.08 mm thick and provides turn-to-turn insulation in windings.⁴⁷

NZ’s enamel wire production situation is uncertain. Enamel wire coating is a specialised process requiring specific varnishes (imported) and controlled application equipment. Pre-event stocks of enamel wire at electrical distributors and motor rewinding shops are finite. As these deplete, alternatives include:

• Paper-insulated wire: Wrapping bare copper wire with thin paper (kraft paper or similar) was the standard before synthetic enamels. It works for transformer windings (Doc #69) where the windings are immersed in oil (the oil provides additional insulation). NZ can produce paper (Doc #29). Performance gap: paper insulation is bulkier than enamel (0.1–0.3 mm per layer versus 0.02–0.08 mm for enamel), reducing the amount of copper that fits in a given winding space by roughly 10–25%, which reduces transformer efficiency. Paper is also limited to approximately 105°C operating temperature (Class A) versus 155–200°C for modern enamel (Class F/H).⁴⁸
• Cotton-covered wire: Bare copper wire wrapped with cotton thread. Used historically for motor and transformer windings. Performance gap: cotton insulation is rated to approximately 90°C (Class Y) versus 155–200°C for modern enamel insulation, bulkier (0.2–0.5 mm per wrap versus 0.02–0.08 mm for enamel), and less uniform in thickness.⁴⁹ This limits motor continuous duty ratings and requires derating motors by approximately 20–40% to avoid overheating. Cotton is not grown commercially in NZ, but existing cotton stocks (clothing, fabric) provide some supply. NZ-grown harakeke fibre might substitute, though its dielectric properties are untested and would need to be verified before use in motor or transformer windings.
• Shellac or varnish coating: Applying a coat of shellac (from existing stocks) or NZ-produced varnish (linseed oil-based) to bare wire provides some insulation. Performance gap: shellac and oil-based varnishes are rated to approximately 105–120°C (versus 155–200°C for synthetic enamel), have lower dielectric strength per unit thickness, and degrade faster under thermal cycling.⁵⁰ Functional for lower-voltage, lower-temperature applications such as signal transformers and low-duty motors.

6.4 Wire types and sizes for recovery applications

The copper wire drawing programme should focus on producing the specific wire types most needed:

Rectangular conductor for transformer windings (Doc #69): Rectangular cross-section wire, typically 2–10 mm wide and 1–4 mm thick, for distribution transformer HV and LV windings. Can be produced by drawing round wire and then flattening through a rolling pass or by drawing through a rectangular die. Paper-insulated for oil-immersed transformers.

Round conductor for motor windings (Doc #95): Round wire, typically 0.5–3.0 mm diameter, enamel-insulated. Used in stator and rotor windings for electric motors.

Power cable conductor: Stranded copper cable (multiple drawn wires twisted together) for distribution and building wiring. Stranding copper wire uses the same principles as steel wire stranding (Doc #52) but requires less force because copper is more flexible. Insulation with NZ-produced materials (paper wrapping, tallow-impregnated cloth, or rubber if available) for lower voltages; pre-event PVC or XLPE insulated cable stocks for higher-voltage applications while they last.

Antenna wire: Bare or enamel-coated copper wire, typically 1–3 mm diameter, for HF radio antennas (Doc #128). Can be produced by wire drawing without specialised insulation.

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7. NZ’S HISTORICAL COPPER MINING

7.1 Known deposits and historical mines

NZ’s copper mining history is brief and small-scale relative to the country’s other mineral resources:

Kawau Island (Hauraki Gulf): The most significant historical copper mine in NZ. Operated intermittently from the 1840s to 1870s, producing copper from chalcopyrite (CuFeS₂) veins in greywacke rock. The mine was never highly profitable and closed as easily accessible ore was exhausted. Total production was modest — estimated at a few hundred tonnes of copper equivalent.⁵¹

Thames/Coromandel: The Coromandel Peninsula’s mineralisation is primarily gold and silver, but some copper minerals occur in association. Small-scale copper mining occurred in the 19th century. No significant copper deposit has been identified in modern geological surveys.⁵²

Dun Mountain/Nelson: The Dun Mountain ophiolite belt in the Nelson-Marlborough region contains copper mineralisation associated with ultramafic rocks. Small copper deposits were identified and briefly worked in the 19th century. The geology suggests the possibility of undiscovered deposits, but nothing of commercial significance has been found.⁵³

Other locations: Minor copper occurrences have been reported in Otago, Southland, and the West Coast, typically in association with other mineralisation. None has been developed to any significant extent.

7.2 Reopening feasibility

Reopening NZ’s historical copper mines faces several challenges:

• Ore grades are low by modern standards. The easily accessible high-grade ore was mined out in the 19th century. Remaining mineralisation is likely lower grade, deeper, and more expensive to extract.
• Mining infrastructure has deteriorated over 100+ years of abandonment. Shafts are collapsed, flooded, or unstable. Reinstatement would require significant engineering effort.
• Processing capability does not exist. Copper ore (typically sulfide minerals like chalcopyrite) must be concentrated, smelted, and refined — none of which NZ has done at any scale. Building this capability for a small, low-grade deposit is a poor investment of labour compared to recycling existing copper or trading for Australian copper.
• Environmental impact. Acid mine drainage from copper sulfide mining is a serious environmental problem. Under recovery conditions, environmental regulation may be relaxed, but acid drainage into water catchments has real consequences for downstream water supply and fisheries.

Assessment: NZ historical copper mining is rated [C] Difficult and low priority. The deposits are too small and too expensive to develop to meaningfully contribute to NZ’s copper supply when recycling and trade provide far more copper per person-year of labour invested. If specific, easily accessible deposits are identified through geological survey, small-scale mining might provide a modest supplement — perhaps 10–50 tonnes per year — but this should not be a planning assumption.

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8. AUSTRALIAN COPPER VIA TASMAN TRADE

8.1 Australia’s copper position

Australia is a major copper producer. Before the event, Australian copper mine production was approximately 800,000–900,000 tonnes per year, with significant smelting and refining capacity (BHP’s Olympic Dam in South Australia, Glencore’s Mount Isa in Queensland, and several other operations).⁵⁴ Australia’s copper production far exceeds its domestic consumption.

Whether Australian copper mining and smelting survive a nuclear catastrophe depends on factors beyond NZ’s control — the severity of nuclear winter effects on Australia, the continuity of Australian government and economy, the state of the mining and smelting infrastructure, and the availability of energy and labour. However, Australia’s mineral resources are so large and the infrastructure so well-established that some level of copper production is likely to continue or resume, even under difficult conditions.

8.2 Trade logistics

Copper is an excellent trade commodity for sail-based Tasman trade (Doc #142):

• High value per unit weight: Refined copper at pre-war prices was approximately US$8,000–10,000 per tonne. Under post-event scarcity, its trade value would be substantially higher.
• Non-perishable: Copper does not degrade in storage or transit.
• Moderate density: Copper has a density of 8.9 g/cm³ — heavy, but a cargo of 10–50 tonnes per voyage is feasible for the sailing vessels described in Doc #138.
• Standard form: Copper cathodes, ingots, or rod are uniform in shape and stackable — well-suited to bulk stowage in a sailing vessel’s hold. At 8.9 g/cm³, copper is dense and requires structural attention to load distribution; a 10-tonne copper cargo occupies approximately 1.1 cubic metres but concentrates weight in a small area of the hold.

NZ’s likely trade goods in exchange include food (NZ’s strongest trade asset under nuclear winter), wool, timber, and manufactured goods. The terms of trade will depend on relative scarcity — if Australia has excess copper but needs food, NZ’s position is strong.

8.3 Timeline

Tasman sail trade is not expected to develop meaningfully before Phase 3 (years 3–7). Vessels must be designed and built (Doc #138), crews trained (Doc #157), and trade relationships established (Doc #140). The first voyages will carry the highest-priority and highest-value goods. Copper might reasonably become a regular import by Phase 3–4, in quantities of perhaps 20–100 tonnes per year initially, scaling as trade capacity grows.

Until trade develops, NZ must rely entirely on its recycled copper stock. This reinforces the importance of establishing domestic smelting and wire drawing capability in Phase 2, and of managing the existing copper inventory carefully.

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9. CRITICAL UNCERTAINTIES

Uncertainty	Impact if unresolved	Resolution
NZ’s total installed copper stock	Determines how long recycling can supply demand	Per-capita modelling validated by sample surveys during asset census (Doc #8)
Existing copper wire drawing equipment status (Nexans NZ, others)	Determines whether drawing capability exists or must be built	Physical assessment of facilities — Phase 1
NZ foundry capability for copper smelting	Determines lead time to first refined copper	Skills and asset census — Phase 1
Purity achievable by fire refining from NZ scrap	Determines whether electrolytic refining is essential or optional	Smelting trials with conductivity testing — Phase 2
Sulfuric acid availability for electrolytic refining	Determines whether high-purity refining is achievable	Acid stock inventory; monitor Doc #113 progress
Copper contamination levels in NZ scrap (iron, zinc, tin)	Determines difficulty of refining and yield	Assay samples from major scrap categories
Australian copper production survival post-event	Determines whether trade-sourced copper supplements domestic supply	Intelligence via HF radio (Doc #128) and initial Tasman contact
Motor and transformer failure rates under isolation	Determines annual copper demand for rewinding	Monitoring programme once operational
Enamel wire insulation substitute viability	Determines whether NZ-insulated wire is adequate for motors and transformers	Testing programme with paper, cotton, and varnish-insulated wire — Phase 2

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CROSS-REFERENCES

• Doc #1 — National Emergency Stockpile Strategy (copper as strategic material)
• Doc #8 — National Skills and Asset Census (copper inventory, smelting and drawing skills)
• Doc #34 — Lubricant Production (tallow and lanolin for wire drawing lubrication)
• Doc #52 — Wire Rope Production (wire drawing principles — steel, complementary)
• Doc #67 — Hydroelectric Maintenance (generator winding copper needs)
• Doc #67 — Transpower Grid Operations (copper demand for grid maintenance)
• Doc #69 — Transformer Rewinding (primary demand driver for copper wire)
• Doc #128 — Micro-Hydro Design (generator winding copper for new construction)
• Doc #89 — NZ Steel Glenbrook (complementary metal production; EAF for possible copper smelting)
• Doc #91 — Machine Shop Operations (die-making for wire drawing, furnace fabrication support)
• Doc #95 — Foundry and Casting (copper smelting and casting capability)
• Doc #95 — Electric Motor Rewinding (second-largest demand driver for copper wire)
• Doc #102 — Charcoal Production (furnace fuel if electric heating unavailable)
• Doc #102 — Wire Drawing and Nails (steel wire drawing — parallel capability development)
• Doc #113 — Sulfuric Acid (required for electrolytic copper refining)
• Doc #128 — HF Radio Network (antenna wire, communications equipment copper needs)
• Doc #138 — Sailing Vessel Design (trade route for Australian copper import)
• Doc #138 — Trans-Tasman Relations (trade framework for copper import)
• Doc #157 — Trade Training Priorities (foundry and wire drawing workforce development)

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1. Per-capita copper stock in developed countries: estimates range from 100–200 kg per person in mature economies. See: Gerst, M.D. and Graedel, T.E., “In-Use Stocks of Metals: Status and Implications,” Environmental Science & Technology, 2008. Also: Kapur, A. and Graedel, T.E., “Copper Mines Above and Below the Ground,” Environmental Science & Technology, 2006. For NZ’s population of approximately 5.2 million, this yields a range of approximately 520,000 tonnes at the midpoint, with a wider 300,000–600,000 tonne uncertainty band reflecting NZ’s somewhat lower per-capita infrastructure intensity compared to North American or European averages.↩︎

2. Australian copper production: Geoscience Australia, “Australia’s Identified Mineral Resources,” annual report. Australia’s copper mine production was approximately 850,000–900,000 tonnes of contained copper per year as of 2022–2023. Major producers include BHP (Olympic Dam, SA), Glencore (Mount Isa, QLD), and numerous smaller operations. https://www.ga.gov.au/↩︎

3. NZ historical copper mining: Harman, R.C., “The Mineral Resources of New Zealand,” NZ Geological Survey Memoir, various editions. Also: Williams, G.J. (ed.), “Economic Geology of New Zealand,” Australasian Institute of Mining and Metallurgy, Monograph 4, 1974. NZ’s copper mining history is documented in these sources as minor and short-lived relative to gold, coal, and other minerals.↩︎

4. NZ copper import data from Stats NZ trade statistics. https://www.stats.govt.nz/ — NZ imports copper in multiple forms: refined copper, copper wire and cable, copper tube, copper fittings, and copper-containing manufactured goods. The 15,000–25,000 tonne estimate covers all forms and requires verification against the most recent trade data.↩︎

5. Per-capita copper stock in developed countries: estimates range from 100–200 kg per person in mature economies. See: Gerst, M.D. and Graedel, T.E., “In-Use Stocks of Metals: Status and Implications,” Environmental Science & Technology, 2008. Also: Kapur, A. and Graedel, T.E., “Copper Mines Above and Below the Ground,” Environmental Science & Technology, 2006. For NZ’s population of approximately 5.2 million, this yields a range of approximately 520,000 tonnes at the midpoint, with a wider 300,000–600,000 tonne uncertainty band reflecting NZ’s somewhat lower per-capita infrastructure intensity compared to North American or European averages.↩︎

6. NZ dwelling count: Stats NZ census data. https://www.stats.govt.nz/ — NZ had approximately 1.9–2.0 million dwellings as of the 2023 Census. Commercial and industrial building stock numbers are less precisely documented but number in the hundreds of thousands.↩︎

7. Copper content in electric motors: varies widely by motor size and type. Small household motors (washing machine, refrigerator) contain approximately 0.1–0.5 kg of copper. Medium industrial motors (5–50 kW) contain approximately 3–30 kg. Large motors (100+ kW) contain 50–500 kg. These are approximate ranges based on general motor design data. See: Copper Development Association, “Copper in Electrical Contacts,” various publications. https://www.copper.org/↩︎

8. NZ transformer fleet count: Transpower and the electricity distribution businesses (EDBs) collectively operate and maintain NZ’s grid and distribution transformers. The exact fleet count is not publicly consolidated in a single published figure; the skills and asset census (Doc #8) should establish this. An indicative range of 30,000–60,000 distribution transformers is derived from comparable countries’ per-capita transformer counts, but requires verification from Transpower and EDB data.↩︎

9. Chorus copper network: Chorus New Zealand operates the copper local loop network. Approximate network length from Chorus annual reports and regulatory filings. The copper telecommunications network is being progressively replaced by fibre under the Ultra-Fast Broadband (UFB) programme, but significant copper plant remains in service, particularly in rural areas. https://www.chorus.co.nz/↩︎

10. NZ vehicle fleet: Ministry of Transport, “New Zealand Vehicle Fleet Statistics,” annual publication. NZ’s registered vehicle fleet was approximately 4.4–4.5 million light vehicles as of 2023–2024, plus additional heavy vehicles, motorcycles, and trailers. https://www.transport.govt.nz/statistics-and-insights/fle...↩︎

11. Post-event copper demand is a rough estimate based on assumed equipment failure rates and replacement needs. The wide range reflects genuine uncertainty about how quickly NZ’s electrical infrastructure degrades and how aggressively new capacity is built. The estimate assumes competent maintenance programmes as described in Doc #22, #69, #71, and #73. Without these programmes, failure rates and copper demand would be higher.↩︎

12. NZ historical copper mining: Harman, R.C., “The Mineral Resources of New Zealand,” NZ Geological Survey Memoir, various editions. Also: Williams, G.J. (ed.), “Economic Geology of New Zealand,” Australasian Institute of Mining and Metallurgy, Monograph 4, 1974. NZ’s copper mining history is documented in these sources as minor and short-lived relative to gold, coal, and other minerals.↩︎

13. NZ geological copper assessments: GNS Science (formerly Institute of Geological and Nuclear Sciences) maintains NZ’s mineral resource data. See: Christie, A.B. and Brathwaite, R.L., “Mineral Commodity Report 7 — Copper,” NZ Mining, 2003. The Coromandel volcanic zone contains epithermal mineralisation (gold-silver dominant) with associated base metals including copper, but no economically significant copper deposit has been identified.↩︎

14. Nexans NZ (formerly Olex NZ): Nexans has cable manufacturing operations in NZ. The extent of wire drawing capability versus cable assembly (drawing imported wire into cable) should be verified. Historical NZ cable manufacturing included substantial copper wire drawing, but industry consolidation and offshore sourcing may have reduced domestic drawing capability. https://www.nexans.co.nz/↩︎

15. Motor rewinding copper demand: NZ’s installed motor fleet includes millions of motors across industrial, commercial, agricultural, and domestic applications. The failure rate and rewinding rate under isolation conditions is uncertain. The 50–500 tonne per year copper demand estimate is based on an assumed annual rewinding volume of approximately 5,000–50,000 motors of average size, which is a wide but reasonable range.↩︎

16. PVC wire insulation hazards when burned: PVC (polyvinyl chloride) releases hydrogen chloride gas (HCl) when thermally decomposed. HCl is toxic and corrosive. Cross-linked polyethylene (XLPE) insulation produces less toxic fumes. Rubber insulation produces sulfur dioxide. See: standard fire safety and polymer chemistry references. Mechanical stripping avoids these hazards entirely and is strongly preferred where practical.↩︎

17. Copper recovery from circuit boards: printed circuit boards contain 10–30% copper by weight. Recovery methods include pyrometallurgical (smelting) and hydrometallurgical (acid leaching). Both produce hazardous byproducts (lead, cadmium from solder; acid waste). For NZ’s purposes, circuit board copper recovery is a low-priority source relative to building wire and plumbing — the copper per unit of processing effort is much lower.↩︎

18. PVC wire insulation hazards when burned: PVC (polyvinyl chloride) releases hydrogen chloride gas (HCl) when thermally decomposed. HCl is toxic and corrosive. Cross-linked polyethylene (XLPE) insulation produces less toxic fumes. Rubber insulation produces sulfur dioxide. See: standard fire safety and polymer chemistry references. Mechanical stripping avoids these hazards entirely and is strongly preferred where practical.↩︎

19. Electrical copper purity standards: ETP (Electrolytic Tough Pitch) copper, UNS C11000, has a minimum copper content of 99.90% and a minimum conductivity of 100% IACS (International Annealed Copper Standard). See: ASTM B5, “Standard Specification for Electrolytic Copper Refinery Shapes.” The IACS standard defines the resistivity of annealed copper at 20°C as 1.7241 × 10⁻⁸ Ω·m.↩︎

20. Effect of impurities on copper conductivity: the impact varies by element. Iron is among the most damaging — 0.04% iron reduces conductivity by approximately 15–25%. Phosphorus is also very damaging. Silver has virtually no effect. See: Davis, J.R. (ed.), “ASM Specialty Handbook: Copper and Copper Alloys,” ASM International, 2001.↩︎

21. Copper melting furnaces: copper’s melting point of 1,085°C is achievable in a wide range of furnace types. See standard foundry references: Heine, R.W. et al., “Principles of Metal Casting,” McGraw-Hill; and specific copper smelting references in Biswas, A.K. and Davenport, W.G., “Extractive Metallurgy of Copper,” Pergamon Press, various editions.↩︎

22. Silica flux for copper smelting: adding silica (SiO₂) as a flux helps remove iron impurities by forming iron silicate slag. This is standard copper smelting practice dating back thousands of years. See: Biswas and Davenport, “Extractive Metallurgy of Copper.”↩︎

23. Oxidation refining of copper: air blowing through molten copper oxidises impurities in order of their oxygen affinity. Iron, zinc, lead, and tin oxidise before copper and are removed in the slag. Noble metals (silver, gold) remain in the copper. See: Biswas and Davenport, “Extractive Metallurgy of Copper,” Chapter on fire refining.↩︎

24. Poling: the traditional method of reducing dissolved oxygen in fire-refined copper by immersing green wood poles in the melt. The hydrocarbons released by the burning wood act as reducing agents, converting Cu₂O back to metallic copper. The technique is documented from the Bronze Age and remained standard practice until the 20th century. See: Tylecote, R.F., “A History of Metallurgy,” The Metals Society, 1976.↩︎

25. Fire refining purity: careful fire refining produces copper of approximately 99.5–99.8% purity. Higher purity requires electrolytic refining. See: Biswas and Davenport, “Extractive Metallurgy of Copper,” Chapter 14 (Fire Refining and Casting).↩︎

26. Electrolytic copper refining: the standard industrial method for producing high-purity copper. Fire-refined copper anodes are dissolved electrochemically and pure copper is deposited on cathodes. The process produces 99.95–99.99% purity copper. See: Biswas and Davenport, “Extractive Metallurgy of Copper,” Chapters 15–16.↩︎

27. Electrolytic refining current requirements: typical industrial practice uses 200–300 A/m² of cathode area. A small refinery with, say, 10 m² of total cathode area would require 2,000–3,000 A at cell voltage of approximately 0.3 V. Cells are connected in series; a bank of 20 cells requires approximately 6 V supply at 2,000–3,000 A, or approximately 12–18 kW. These are modest power requirements well within NZ’s grid capability.↩︎

28. Sulfuric acid for electrolytic copper refining: the electrolyte requires approximately 150–200 g/L H₂SO₄. For a small refinery with 10,000 litres of electrolyte, the initial acid charge is approximately 1.5–2 tonnes. Ongoing acid consumption is low (acid is recycled within the circuit) but periodic makeup is needed. NZ’s pre-event sulfuric acid stocks (at fertiliser plants, chemical distributors, industrial users) should be inventoried. See Doc #113 for NZ sulfuric acid production feasibility.↩︎

29. Electrolytic copper refining: the standard industrial method for producing high-purity copper. Fire-refined copper anodes are dissolved electrochemically and pure copper is deposited on cathodes. The process produces 99.95–99.99% purity copper. See: Biswas and Davenport, “Extractive Metallurgy of Copper,” Chapters 15–16.↩︎

30. Sulfuric acid for electrolytic copper refining: the electrolyte requires approximately 150–200 g/L H₂SO₄. For a small refinery with 10,000 litres of electrolyte, the initial acid charge is approximately 1.5–2 tonnes. Ongoing acid consumption is low (acid is recycled within the circuit) but periodic makeup is needed. NZ’s pre-event sulfuric acid stocks (at fertiliser plants, chemical distributors, industrial users) should be inventoried. See Doc #113 for NZ sulfuric acid production feasibility.↩︎

31. Electrical copper purity standards: ETP (Electrolytic Tough Pitch) copper, UNS C11000, has a minimum copper content of 99.90% and a minimum conductivity of 100% IACS (International Annealed Copper Standard). See: ASTM B5, “Standard Specification for Electrolytic Copper Refinery Shapes.” The IACS standard defines the resistivity of annealed copper at 20°C as 1.7241 × 10⁻⁸ Ω·m.↩︎

32. NZ foundry capability: NZ has several foundries casting iron, steel, bronze, and aluminium. Examples include foundry operations in Auckland, Christchurch, and regional centres. The NZ Foundry Association (if still active) or industry contacts through the skills census would provide the most current data. Capability varies from small jobbing foundries to larger operations serving mining and marine industries.↩︎

33. NZ foundry capability: NZ has several foundries casting iron, steel, bronze, and aluminium. Examples include foundry operations in Auckland, Christchurch, and regional centres. The NZ Foundry Association (if still active) or industry contacts through the skills census would provide the most current data. Capability varies from small jobbing foundries to larger operations serving mining and marine industries.↩︎

34. Crucible furnace copper smelting: one of the oldest metallurgical technologies, used continuously from approximately 4000 BCE to the present. Modern crucible furnaces for copper use silicon carbide or graphite-clay crucibles in gas, electric, or coke-fired furnaces. See: foundry reference texts and Biswas and Davenport, “Extractive Metallurgy of Copper.”↩︎

35. Refractory fire brick and cement in NZ: high-alumina fire brick is used in NZ’s foundry, ceramics, and kiln industries and is stocked by industrial suppliers (e.g., Winstone Wallboards, industrial ceramics suppliers). The specific stock levels and supplier locations should be confirmed through the asset census (Doc #8). If pre-event stocks are depleted, fire brick can in principle be produced from NZ clays (kaolin and high-alumina clays occur in NZ — Matauri Bay kaolin, Southland clays), but clay processing to refractories requires kiln capability and is a Phase 3–4 project.↩︎

36. Crucible materials: silicon carbide crucibles are the modern standard for copper melting due to their thermal shock resistance and long life. Graphite-clay crucibles are the traditional alternative. Steel crucibles can melt copper but iron contamination of the melt is a concern — iron dissolves slightly into molten copper from a steel crucible, reducing conductivity. If steel crucibles must be used, the copper should be tested for iron content and re-refined if necessary.↩︎

37. Crucible furnace production rate assumptions: the 100–300 kg/day estimate assumes a furnace with 50–150 kg crucible capacity, a heat cycle of 3–5 hours from cold charge to pour (including 1–2 hours melt time, 30–60 minutes oxidise and pole, and casting time), and 2–4 heats per working day. Actual output depends on furnace efficiency, scrap quality, and crew experience. New operations should assume the lower end of this range until procedures are proven.↩︎

38. Induction furnace copper melting: induction furnaces heat the charge directly through electromagnetic coupling, producing rapid, clean melting with minimal contamination. They are the preferred furnace type for copper melting in modern practice. See: foundry engineering references; Rudnev, V. et al., “Handbook of Induction Heating,” Marcel Dekker, 2003.↩︎

39. Induction furnace power supply: a coreless induction furnace for copper uses a medium-frequency (1–10 kHz) power supply. Modern supplies use IGBT (insulated gate bipolar transistor) or thyristor-based inverters. Building such a supply requires electronic components from pre-event stocks but is within NZ’s power electronics engineering capability. Older furnace designs used motor-generator sets (a motor driving a generator at the desired frequency) — these are mechanically simpler and could be fabricated from NZ components.↩︎

40. Energy requirements for copper melting: theoretical minimum energy to heat copper from 20°C to 1,100°C and melt it is approximately 550 kJ/kg (390 kJ/kg sensible heat + 205 kJ/kg latent heat = 595 kJ/kg, but some references use slightly different values depending on temperature range). In practice, furnace efficiency ranges from 30–60% for crucible furnaces (rest is lost to the furnace structure and exhaust) to 60–80% for induction furnaces. At 50% efficiency, the practical energy requirement is approximately 1.1 MJ/kg or 0.3 kWh/kg for induction, or approximately 1.5–3.0 kWh/kg for less efficient furnaces.↩︎

41. NZ household electricity consumption: approximately 7,000–8,000 kWh per year on average. Source: MBIE Energy in NZ publications. https://www.mbie.govt.nz/building-and-energy/energy-and-n...↩︎

42. Gravity casting of copper rod: the historical method for producing copper rod and bar stock before continuous casting was developed. Moulds can be cast iron, machined steel, or graphite. The copper is poured at approximately 1,100–1,150°C (slightly above the melting point to ensure the mould fills completely). Surface quality is inferior to continuously cast rod but adequate for subsequent wire drawing, which removes surface defects.↩︎

43. Continuous casting of copper: the modern industrial method (e.g., Southwire SCR process, Properzi process) produces copper rod at high speed and consistent quality. Building a full-scale continuous casting line is a major engineering project, but a simplified small-scale version — essentially a cooled mould fed from a tundish — is within NZ’s engineering capability for modest production rates. See: Adams, J.A., “Continuous Casting of Copper,” in Biswas and Davenport, “Extractive Metallurgy of Copper.”↩︎

44. Copper wire drawing parameters: copper’s high ductility allows larger area reductions per drawing pass compared to steel. Total area reduction before annealing can reach 90–95% (compared to 75–85% for steel). See: ASM Handbook, Volume 14A, “Metalworking: Bulk Forming,” Chapter on wire drawing.↩︎

45. Tool steel die life for copper drawing: copper’s low hardness (Brinell 45–50 HB annealed) produces low die wear relative to steel wire. Tool steel dies (D2 or equivalent, 58–62 HRC) are routinely used for copper wire drawing in developing-economy contexts. Die life depends on wire diameter, lubricant quality, and die geometry; 50–200 tonnes per regrind is a representative range from wire drawing practice. Tungsten carbide dies extend this to 500–2,000 tonnes but require harder grinding equipment and are more fragile under shock loading. See: Wright, R.N., “Wire Technology,” Butterworth-Heinemann, 2011, Chapter on die materials.↩︎

46. Wire drawing lubrication for copper: the primary concern is preventing copper pickup on the die (galling). Tallow and tallow-derived soaps have been used historically for copper wire drawing and perform adequately. Modern lubricants are synthetic oil-based emulsions providing better surface finish. For electrical wire where surface finish affects insulation adhesion, cleaner lubricants are preferred. See: Wright, R.N., “Wire Technology,” Butterworth-Heinemann, 2011.↩︎

47. Enamel wire insulation: magnet wire is typically coated with polyester, polyurethane, or polyimide enamel in a specialised coating line. The wire passes through a varnish applicator, then through a curing oven at 300–500°C (depending on the enamel type). Multiple coats are applied to build up the required insulation thickness. See: IEC 60317 series (specifications for particular types of winding wires). NZ production of enamel varnish is not feasible without specialised polymer chemistry; substitute insulation methods are discussed in Section 6.3.↩︎

48. Electrical insulation thermal classes: IEC 60085 defines insulation classes by maximum continuous operating temperature. Class Y (cotton, silk, paper without impregnation): 90°C. Class A (paper or cotton impregnated with oil or varnish): 105°C. Class F (modern polyester enamel): 155°C. Class H (polyimide enamel): 180°C. Some modern enamels are rated to 200°C or higher. The performance gap between historical insulation materials (Class Y/A) and modern enamel (Class F/H) is significant — motors insulated with Class A materials must be derated 20–40% relative to their Class F ratings to avoid thermal damage. See: IEC 60085, “Electrical insulation — Thermal evaluation and designation.”↩︎

49. Electrical insulation thermal classes: IEC 60085 defines insulation classes by maximum continuous operating temperature. Class Y (cotton, silk, paper without impregnation): 90°C. Class A (paper or cotton impregnated with oil or varnish): 105°C. Class F (modern polyester enamel): 155°C. Class H (polyimide enamel): 180°C. Some modern enamels are rated to 200°C or higher. The performance gap between historical insulation materials (Class Y/A) and modern enamel (Class F/H) is significant — motors insulated with Class A materials must be derated 20–40% relative to their Class F ratings to avoid thermal damage. See: IEC 60085, “Electrical insulation — Thermal evaluation and designation.”↩︎

50. Electrical insulation thermal classes: IEC 60085 defines insulation classes by maximum continuous operating temperature. Class Y (cotton, silk, paper without impregnation): 90°C. Class A (paper or cotton impregnated with oil or varnish): 105°C. Class F (modern polyester enamel): 155°C. Class H (polyimide enamel): 180°C. Some modern enamels are rated to 200°C or higher. The performance gap between historical insulation materials (Class Y/A) and modern enamel (Class F/H) is significant — motors insulated with Class A materials must be derated 20–40% relative to their Class F ratings to avoid thermal damage. See: IEC 60085, “Electrical insulation — Thermal evaluation and designation.”↩︎

51. NZ historical copper mining: Harman, R.C., “The Mineral Resources of New Zealand,” NZ Geological Survey Memoir, various editions. Also: Williams, G.J. (ed.), “Economic Geology of New Zealand,” Australasian Institute of Mining and Metallurgy, Monograph 4, 1974. NZ’s copper mining history is documented in these sources as minor and short-lived relative to gold, coal, and other minerals.↩︎

52. NZ geological copper assessments: GNS Science (formerly Institute of Geological and Nuclear Sciences) maintains NZ’s mineral resource data. See: Christie, A.B. and Brathwaite, R.L., “Mineral Commodity Report 7 — Copper,” NZ Mining, 2003. The Coromandel volcanic zone contains epithermal mineralisation (gold-silver dominant) with associated base metals including copper, but no economically significant copper deposit has been identified.↩︎

53. Dun Mountain ophiolite: the Dun Mountain ultramafic belt in Nelson-Marlborough is geologically significant but has not yielded commercially significant copper deposits. See: Coombs, D.S. et al., “The Dun Mountain Ophiolite Belt,” Geological Society of New Zealand Miscellaneous Publication. Some copper-bearing sulfide mineralisation occurs in association with the ultramafic rocks, but grades and tonnages are poorly characterised.↩︎

54. Australian copper production: Geoscience Australia, “Australia’s Identified Mineral Resources,” annual report. Australia’s copper mine production was approximately 850,000–900,000 tonnes of contained copper per year as of 2022–2023. Major producers include BHP (Olympic Dam, SA), Glencore (Mount Isa, QLD), and numerous smaller operations. https://www.ga.gov.au/↩︎