Scope: Structural, hydraulic, electrical, and mechanical reference tables for field engineering without specialist software. Values are computed from the formulae stated or taken from the cited standards. Any calculation can be re-derived from the governing equations given in each section preamble.
Material basis: Timber data uses Radiata Pine (SG8/MSG8 grade) per NZS 3603. Hydraulic data uses Hazen-Williams (H-W). Electrical data follows AS/NZS 3008.1.1 principles. Thread data follows ISO 68-1 and ISO 261/262.
Conservative use: These tables give working-load deflections and capacities. Apply appropriate safety factors per the relevant design standard. In the absence of a licensed engineer, use a minimum factor of 2.0 on calculated loads for life-safety applications.
1. Beam Deflection Tables
Radiata Pine, E = 8.0 GPa (NZS 3603 SG8/MSG8). Sections listed as depth × breadth (standard NZ notation).
Reading the tables: For a point-load table, multiply the tabulated value by your actual load in kN to obtain mid-span deflection in mm. For a UDL table, multiply by load in kN/m.
Span/deflection ratio check: L/360 is a common serviceability limit for floors (e.g. 5 m span → 13.9 mm limit). L/240 is typical for roofs.
1.1 Simply Supported — Central Point Load
Formula: δ = PL³ / (48EI)
Tabulated: Deflection per kN of point load (mm/kN)
| Span (m) | 90×45 | 140×45 | 190×45 | 240×45 | 290×45 |
|---|---|---|---|---|---|
| I (m⁴) | I=2.7×10⁻⁶ m⁴ | I=10.3×10⁻⁶ m⁴ | I=25.7×10⁻⁶ m⁴ | I=51.8×10⁻⁶ m⁴ | I=91.5×10⁻⁶ m⁴ |
| 2 m | 7.62 | 2.02 | 0.81 | 0.40 | 0.23 |
| 3 m | 25.72 | 6.83 | 2.73 | 1.36 | 0.77 |
| 4 m | 60.97 | 16.20 | 6.48 | 3.22 | 1.82 |
| 5 m | 119.07 | 31.63 | 12.66 | 6.28 | 3.56 |
| 6 m | 205.76 | 54.66 | 21.87 | 10.85 | 6.15 |
| 7 m | 326.74 | 86.81 | 34.73 | 17.23 | 9.77 |
| 8 m | 487.73 | 129.58 | 51.84 | 25.72 | 14.58 |
1.2 Simply Supported — Uniformly Distributed Load (UDL)
Formula: δ = 5wL⁴ / (384EI)
Tabulated: Deflection per kN/m of UDL (mm per kN/m)
| Span (m) | 90×45 | 140×45 | 190×45 | 240×45 | 290×45 |
|---|---|---|---|---|---|
| I (m⁴) | I=2.7×10⁻⁶ m⁴ | I=10.3×10⁻⁶ m⁴ | I=25.7×10⁻⁶ m⁴ | I=51.8×10⁻⁶ m⁴ | I=91.5×10⁻⁶ m⁴ |
| 2 m | 9.53 | 2.53 | 1.01 | 0.50 | 0.28 |
| 3 m | 48.23 | 12.81 | 5.13 | 2.54 | 1.44 |
| 4 m | 152.42 | 40.49 | 16.20 | 8.04 | 4.56 |
| 5 m | 372.11 | 98.86 | 39.55 | 19.62 | 11.12 |
| 6 m | 771.60 | 204.99 | 82.01 | 40.69 | 23.06 |
| 7 m | 1429.49 | 379.77 | 151.93 | 75.38 | 42.73 |
| 8 m | 2438.65 | 647.88 | 259.19 | 128.60 | 72.89 |
1.3 Cantilever — End Point Load
Formula: δ = PL³ / (3EI)
Tabulated: Deflection per kN of point load (mm/kN)
| Span (m) | 90×45 | 140×45 | 190×45 | 240×45 | 290×45 |
|---|---|---|---|---|---|
| I (m⁴) | I=2.7×10⁻⁶ m⁴ | I=10.3×10⁻⁶ m⁴ | I=25.7×10⁻⁶ m⁴ | I=51.8×10⁻⁶ m⁴ | I=91.5×10⁻⁶ m⁴ |
| 2 m | 121.93 | 32.39 | 12.96 | 6.43 | 3.64 |
| 3 m | 411.52 | 109.33 | 43.74 | 21.70 | 12.30 |
| 4 m | 975.46 | 259.15 | 103.68 | 51.44 | 29.16 |
| 5 m | 1905.20 | 506.15 | 202.49 | 100.47 | 56.95 |
| 6 m | 3292.18 | 874.64 | 349.91 | 173.61 | 98.41 |
| 7 m | 5227.86 | 1388.89 | 555.64 | 275.69 | 156.26 |
| 8 m | 7803.69 | 2073.21 | 829.40 | 411.52 | 233.26 |
1.4 Cantilever — Uniformly Distributed Load (UDL)
Formula: δ = wL⁴ / (8EI)
Tabulated: Deflection per kN/m of UDL (mm per kN/m)
| Span (m) | 90×45 | 140×45 | 190×45 | 240×45 | 290×45 |
|---|---|---|---|---|---|
| I (m⁴) | I=2.7×10⁻⁶ m⁴ | I=10.3×10⁻⁶ m⁴ | I=25.7×10⁻⁶ m⁴ | I=51.8×10⁻⁶ m⁴ | I=91.5×10⁻⁶ m⁴ |
| 2 m | 91.45 | 24.30 | 9.72 | 4.82 | 2.73 |
| 3 m | 462.96 | 123.00 | 49.21 | 24.41 | 13.84 |
| 4 m | 1463.19 | 388.73 | 155.51 | 77.16 | 43.74 |
| 5 m | 3572.25 | 949.04 | 379.67 | 188.38 | 106.78 |
| 6 m | 7407.41 | 1967.93 | 787.29 | 390.62 | 221.41 |
| 7 m | 13723.14 | 3645.83 | 1458.55 | 723.68 | 410.19 |
| 8 m | 23411.07 | 6219.63 | 2488.21 | 1234.57 | 699.77 |
Source: Beam deflection formulae from Roark’s Formulas for Stress and Strain (Young & Budynas, 8th ed., Table 3). Section properties from NZS 3603:1993 and standard metric timber sizes.
2. Pipe Flow Tables (Hazen-Williams)
Formula: Q = 0.849 × C × A × R^0.63 × S^0.54
where Q = flow (m³/s), C = roughness coefficient, A = pipe
cross-section area (m²), R = hydraulic radius = D/4 (m), S =
hydraulic gradient (m/m, i.e. head loss per unit length).
Flow values below are in litres per second (L/s) for
full-bore flow.
Velocity can be estimated as V = Q / A. Recommended maximum design velocity: 1.5–3.0 m/s for water supply; 0.6–1.0 m/s minimum for self-cleansing in sewers.
2.1 C = 150 — New smooth plastic (PVC/PE)
| Diameter (mm) | 1:100 | 1:200 | 1:500 | 1:1000 |
|---|---|---|---|---|
| Internal dia | S=0.01000 | S=0.00500 | S=0.00200 | S=0.00100 |
| 25 | 0.21 | 0.15 | 0.089 | 0.061 |
| 32 | 0.41 | 0.28 | 0.17 | 0.12 |
| 40 | 0.73 | 0.50 | 0.31 | 0.21 |
| 50 | 1.32 | 0.90 | 0.55 | 0.38 |
| 65 | 2.62 | 1.80 | 1.10 | 0.76 |
| 80 | 4.53 | 3.11 | 1.90 | 1.31 |
| 100 | 8.14 | 5.60 | 3.41 | 2.35 |
| 150 | 23.7 | 16.3 | 9.92 | 6.82 |
| 200 | 50.4 | 34.7 | 21.1 | 14.5 |
2.2 C = 130 — New steel / galvanised
| Diameter (mm) | 1:100 | 1:200 | 1:500 | 1:1000 |
|---|---|---|---|---|
| Internal dia | S=0.01000 | S=0.00500 | S=0.00200 | S=0.00100 |
| 25 | 0.18 | 0.13 | 0.077 | 0.053 |
| 32 | 0.35 | 0.24 | 0.15 | 0.10 |
| 40 | 0.63 | 0.44 | 0.27 | 0.18 |
| 50 | 1.14 | 0.78 | 0.48 | 0.33 |
| 65 | 2.27 | 1.56 | 0.95 | 0.66 |
| 80 | 3.92 | 2.70 | 1.65 | 1.13 |
| 100 | 7.06 | 4.85 | 2.96 | 2.04 |
| 150 | 20.5 | 14.1 | 8.60 | 5.91 |
| 200 | 43.7 | 30.0 | 18.3 | 12.6 |
2.3 C = 100 — Old steel / concrete
| Diameter (mm) | 1:100 | 1:200 | 1:500 | 1:1000 |
|---|---|---|---|---|
| Internal dia | S=0.01000 | S=0.00500 | S=0.00200 | S=0.00100 |
| 25 | 0.14 | 0.097 | 0.059 | 0.041 |
| 32 | 0.27 | 0.19 | 0.11 | 0.078 |
| 40 | 0.49 | 0.34 | 0.20 | 0.14 |
| 50 | 0.88 | 0.60 | 0.37 | 0.25 |
| 65 | 1.75 | 1.20 | 0.73 | 0.50 |
| 80 | 3.02 | 2.08 | 1.27 | 0.87 |
| 100 | 5.43 | 3.73 | 2.28 | 1.57 |
| 150 | 15.8 | 10.8 | 6.61 | 4.55 |
| 200 | 33.6 | 23.1 | 14.1 | 9.69 |
2.4 C = 80 — Old cast iron / corroded steel
| Diameter (mm) | 1:100 | 1:200 | 1:500 | 1:1000 |
|---|---|---|---|---|
| Internal dia | S=0.01000 | S=0.00500 | S=0.00200 | S=0.00100 |
| 25 | 0.11 | 0.078 | 0.048 | 0.033 |
| 32 | 0.22 | 0.15 | 0.091 | 0.063 |
| 40 | 0.39 | 0.27 | 0.16 | 0.11 |
| 50 | 0.70 | 0.48 | 0.29 | 0.20 |
| 65 | 1.40 | 0.96 | 0.59 | 0.40 |
| 80 | 2.41 | 1.66 | 1.01 | 0.70 |
| 100 | 4.34 | 2.99 | 1.82 | 1.25 |
| 150 | 12.6 | 8.68 | 5.29 | 3.64 |
| 200 | 26.9 | 18.5 | 11.3 | 7.75 |
Pipe Velocity Reference
Full-bore velocity V = Q/A. At 1 L/s through each pipe size:
| Diameter (mm) | Area (cm²) | V at 1 L/s (m/s) |
|---|---|---|
| 25 | 4.91 | 2.037 |
| 32 | 8.04 | 1.243 |
| 40 | 12.57 | 0.796 |
| 50 | 19.63 | 0.509 |
| 65 | 33.18 | 0.301 |
| 80 | 50.27 | 0.199 |
| 100 | 78.54 | 0.127 |
| 150 | 176.71 | 0.057 |
| 200 | 314.16 | 0.032 |
Source: Hazen-Williams equation per Mays, L.W. (ed.), Water Distribution Systems Handbook (McGraw-Hill, 2000), §2.4. C-values per Chadwick, A. et al., Hydraulics in Civil and Environmental Engineering (5th ed., 2013), Table 8.1.
3. Timber Span Tables
Material: Radiata Pine, MSG8/SG8 grade, NZS 3603:1993.
Design bending strength f’b = 14.0 MPa (characteristic 18.0 MPa ×
modification factors k₁=0.8 for long-term load duration, k₄=1.0
for dry service, k₈=1.0 for single member — conservative).
E = 8.0 GPa.
Spans governed by lesser of bending (M ≤ f’b·Z, wL²/8) or
deflection (L/360 floor, L/240 roof). Values rounded DOWN to
nearest 50 mm.
Load basis: Floor = 1.5 kPa (dead + live).
Roof/rafter = 0.5 kPa (dead + live, light roofing).
Tributary load per joist or rafter (kN/m) = pressure ×
spacing.
3.1 Floor Joists — Design Load 1.5 kPa
Joist spacing: 400 mm centres (w = 0.600 kN/m)
| Section (d×b mm) | Max Span (m) | Governed by |
|---|---|---|
| 140×45 | 3.05 | deflection |
| 190×45 | 4.15 | deflection |
| 240×45 | 5.25 | deflection |
| 290×45 | 6.35 | deflection |
Joist spacing: 600 mm centres (w = 0.900 kN/m)
| Section (d×b mm) | Max Span (m) | Governed by |
|---|---|---|
| 140×45 | 2.65 | deflection |
| 190×45 | 3.65 | deflection |
| 240×45 | 4.60 | deflection |
| 290×45 | 5.55 | deflection |
3.2 Rafters — Design Load 0.5 kPa
Rafter spacing: 600 mm centres (w = 0.300 kN/m)
| Section (d×b mm) | Max Span (m) | Governed by |
|---|---|---|
| 90×45 | 2.85 | deflection |
| 140×45 | 4.40 | deflection |
| 190×45 | 6.00 | deflection |
| 240×45 | 7.60 | deflection |
| 290×45 | 9.20 | deflection |
Rafter spacing: 900 mm centres (w = 0.450 kN/m)
| Section (d×b mm) | Max Span (m) | Governed by |
|---|---|---|
| 90×45 | 2.45 | deflection |
| 140×45 | 3.85 | deflection |
| 190×45 | 5.25 | deflection |
| 240×45 | 6.65 | deflection |
| 290×45 | 8.00 | deflection |
Note: These spans are indicative for initial sizing. Final design must account for lateral restraint, notching, end fixity, load sharing (k₈ > 1.0 for multiple members), and connection capacity per NZS 3603:1993. Spans may be extended by 5–15% when load sharing applies.
Source: NZS 3603:1993 Timber Structures Standard, Tables 2.1, 2.4, B1–B6. Deflection limits per NZS 3604:2011 §6.
4. Wire and Cable Ampacity — Copper Conductors
Current-carrying capacity (amperes) for copper conductors with
thermoplastic (PVC/XLPE) insulation, 75°C conductor temperature
rating.
Reference standard: AS/NZS 3008.1.1:2017, Table 7.
Installation methods:
- In conduit: conductors in enclosed conduit, 40°C
ambient
- Clipped direct: surface-mounted, 30°C ambient
- Free air: spaced away from surface, 30°C ambient
Voltage drop (approx, 230V single-phase): V_drop = I × R × L / 1000 where R (mΩ/m) from table below.
| Size (mm²) | In Conduit (A) | Clipped Direct (A) | Free Air (A) | R at 75°C (mΩ/m) |
|---|---|---|---|---|
| 1.0 | 10 | 13 | 15 | 20.92 |
| 1.5 | 13 | 17 | 20 | 13.95 |
| 2.5 | 18 | 24 | 27 | 8.37 |
| 4.0 | 24 | 32 | 36 | 5.23 |
| 6.0 | 31 | 41 | 46 | 3.49 |
| 10.0 | 42 | 57 | 63 | 2.09 |
| 16.0 | 57 | 76 | 85 | 1.31 |
| 25.0 | 75 | 101 | 112 | 0.84 |
4.1 Derating Factors
Apply derating factors by multiplying tabulated current by all applicable factors.
| Condition | Derating Factor |
|---|---|
| 2 circuits grouped (touching) | 0.80 |
| 3 circuits grouped | 0.70 |
| 4–6 circuits grouped | 0.60 |
| 7–9 circuits grouped | 0.50 |
| Ambient 45°C (vs 30°C base) | 0.91 |
| Ambient 50°C | 0.82 |
| Ambient 55°C | 0.71 |
| Ambient 60°C | 0.58 |
| Fully enclosed in thermal insulation | 0.50 |
| Partially covered by thermal insulation | 0.75 |
4.2 Common Voltage Drop Budget (230 V, ≤5% limit = 11.5 V)
Maximum single-phase circuit length (m) for 5% voltage drop at
full load:
L_max = 11.5 × 1000 / (I × R_mΩm × 2) (factor 2 for return
conductor)
| Size (mm²) | 10 A load | 16 A load | 20 A load | 32 A load |
|---|---|---|---|---|
| 1.0 | 27 m | 17 m | 14 m | 9 m |
| 1.5 | 41 m | 26 m | 21 m | 13 m |
| 2.5 | 69 m | 43 m | 34 m | 21 m |
| 4.0 | 110 m | 69 m | 55 m | 34 m |
| 6.0 | 165 m | 103 m | 82 m | 52 m |
| 10.0 | 275 m | 172 m | 137 m | 86 m |
| 16.0 | 440 m | 275 m | 220 m | 137 m |
| 25.0 | 687 m | 430 m | 344 m | 215 m |
Source: AS/NZS 3008.1.1:2017 Electrical Installations — Selection of Cables, Table 7 (current capacity) and Table 30 (resistance). Derating factors from Tables 22–25 of the same standard.
5. ISO Metric Thread Dimensions
Based on ISO 68-1 (thread profile), ISO 261 (coarse series), ISO 262 (fine series).
Formulae (all dimensions in mm):
- Pitch diameter d₂ = D − 0.6495 × P
- Minor dia (bolt) d₁ = D − 1.2269 × P
- Minor dia (nut) D₁ = D − 1.0825 × P
- Tap drill (75% thread) ≈ D − P
For class 6g/6H (standard commercial tolerance), add tolerance from ISO 965-1.
5.1 Coarse Pitch Series
| Size | Pitch (mm) | Pitch Dia d₂ (mm) | Minor (bolt) d₁ (mm) | Minor (nut) D₁ (mm) | Tap Drill (mm) |
|---|---|---|---|---|---|
| M3 | 0.50 | 2.675 | 2.387 | 2.459 | 2.50 |
| M4 | 0.70 | 3.545 | 3.141 | 3.242 | 3.30 |
| M5 | 0.80 | 4.480 | 4.018 | 4.134 | 4.20 |
| M6 | 1.00 | 5.351 | 4.773 | 4.918 | 5.00 |
| M8 | 1.25 | 7.188 | 6.466 | 6.647 | 6.75 |
| M10 | 1.50 | 9.026 | 8.160 | 8.376 | 8.50 |
| M12 | 1.75 | 10.863 | 9.853 | 10.106 | 10.25 |
| M14 | 2.00 | 12.701 | 11.546 | 11.835 | 12.00 |
| M16 | 2.00 | 14.701 | 13.546 | 13.835 | 14.00 |
| M18 | 2.50 | 16.376 | 14.933 | 15.294 | 15.50 |
| M20 | 2.50 | 18.376 | 16.933 | 17.294 | 17.50 |
| M22 | 2.50 | 20.376 | 18.933 | 19.294 | 19.50 |
| M24 | 3.00 | 22.052 | 20.319 | 20.753 | 21.00 |
5.2 Fine Pitch Series
| Size | Pitch (mm) | Pitch Dia d₂ (mm) | Minor (bolt) d₁ (mm) | Minor (nut) D₁ (mm) | Tap Drill (mm) |
|---|---|---|---|---|---|
| M6 | 0.75 | 5.513 | 5.080 | 5.188 | 5.25 |
| M8 | 1.00 | 7.351 | 6.773 | 6.918 | 7.00 |
| M10 | 1.25 | 9.188 | 8.466 | 8.647 | 8.75 |
| M12 | 1.25 | 11.188 | 10.466 | 10.647 | 10.75 |
| M14 | 1.50 | 13.026 | 12.160 | 12.376 | 12.50 |
| M16 | 1.50 | 15.026 | 14.160 | 14.376 | 14.50 |
| M18 | 1.50 | 17.026 | 16.160 | 16.376 | 16.50 |
| M20 | 1.50 | 19.026 | 18.160 | 18.376 | 18.50 |
| M22 | 1.50 | 21.026 | 20.160 | 20.376 | 20.50 |
| M24 | 2.00 | 22.701 | 21.546 | 21.835 | 22.00 |
5.3 Thread Engagement and Strength Notes
- Minimum thread engagement in steel: 1.0 × D
- Minimum thread engagement in aluminium: 1.5 × D
- Minimum thread engagement in cast iron / grey iron: 1.25 ×
D
- Minimum thread engagement in plastics: 2.0 × D
- Standard nut height (coarse) ≈ 0.8 × D (grade 8 nuts ≈ 1.0 ×
D)
- Self-locking torque (nyloc inserts): add ~20–30% to standard torque
Source: ISO 68-1:2013 General purpose screw threads — Basic profile. ISO 261:1998 ISO general-purpose metric screw threads — General plan. Tap drill guidance per Machinery’s Handbook (31st ed., p. 1924).
6. Metric Bolt Proof Loads and Tightening Torques
Per ISO 898-1:2013 Mechanical properties of fasteners — Bolts, screws and studs.
Proof load = proof stress × tensile stress
area.
Tensile stress area: A_s = π/4 × (D − 0.9382P)² (ISO 898-1 Annex
A).
Tightening torque is indicative for lightly oiled or as-received uncoated steel (nut factor K ≈ 0.20). T ≈ K × F_proof × D. Actual torque varies with friction; always use measured or published torque for critical joints.
Proof stresses used (MPa):
- Grade 4.8: 310 MPa
- Grade 8.8: 580 MPa (conservative; spec is 600 for M≤16, 580 for
M>16)
- Grade 10.9: 830 MPa
- Grade 12.9: 970 MPa
6.1 Tensile Stress Areas
| Size | Pitch (mm) | Stress Area A_s (mm²) |
|---|---|---|
| M6 | 1.00 | 20.1 |
| M8 | 1.25 | 36.6 |
| M10 | 1.50 | 58.0 |
| M12 | 1.75 | 84.3 |
| M14 | 2.00 | 115.4 |
| M16 | 2.00 | 156.7 |
| M18 | 2.50 | 192.5 |
| M20 | 2.50 | 244.8 |
| M22 | 2.50 | 303.4 |
| M24 | 3.00 | 352.5 |
6.2 Proof Loads (kN)
| Size | Grade 4.8 | Grade 8.8 | Grade 10.9 | Grade 12.9 |
|---|---|---|---|---|
| M6 | 6.2 | 11.7 | 16.7 | 19.5 |
| M8 | 11.3 | 21.2 | 30.4 | 35.5 |
| M10 | 18.0 | 33.6 | 48.1 | 56.2 |
| M12 | 26.1 | 48.9 | 69.9 | 81.7 |
| M14 | 35.8 | 67.0 | 95.8 | 112.0 |
| M16 | 48.6 | 90.9 | 130.0 | 152.0 |
| M18 | 59.7 | 111.6 | 159.8 | 186.7 |
| M20 | 75.9 | 142.0 | 203.2 | 237.5 |
| M22 | 94.1 | 176.0 | 251.8 | 294.3 |
| M24 | 109.3 | 204.5 | 292.6 | 341.9 |
6.3 Indicative Tightening Torques (N·m), K = 0.20
| Size | Grade 4.8 | Grade 8.8 | Grade 10.9 | Grade 12.9 |
|---|---|---|---|---|
| M6 | 7 | 14 | 20 | 23 |
| M8 | 18 | 34 | 49 | 57 |
| M10 | 36 | 67 | 96 | 112 |
| M12 | 63 | 117 | 168 | 196 |
| M14 | 100 | 187 | 268 | 314 |
| M16 | 155 | 291 | 416 | 486 |
| M18 | 215 | 402 | 575 | 672 |
| M20 | 304 | 568 | 813 | 950 |
| M22 | 414 | 774 | 1108 | 1295 |
| M24 | 525 | 981 | 1404 | 1641 |
6.4 Bolt Identification — Head Markings
| Grade | Yield/Tensile (MPa) | Typical use |
|---|---|---|
| 4.8 | 320 / 420 | General light structural, non-critical joints |
| 8.8 | 640 / 800 | Standard structural bolts; most structural connections |
| 10.9 | 940 / 1040 | High-strength; flanged connections, critical machinery |
| 12.9 | 1100 / 1220 | Very high strength; socket-head cap screws, aerospace |
6.5 Nut and Washer Selection
Match nut grade to bolt grade:
- Grade 4 nuts → Grade 4.8 bolts
- Grade 8 nuts → Grade 8.8 bolts
- Grade 10 nuts → Grade 10.9 bolts
- Grade 12 nuts → Grade 12.9 bolts
Hardened washers (Grade 300HV) required under head and nut for Grade 8.8 and above in steel structures. Plain washers acceptable for Grade 4.8 in timber and light construction.
Source: ISO 898-1:2013 Mechanical properties of fasteners — Bolts, screws and studs. Torque estimation from Shigley’s Mechanical Engineering Design (10th ed., §8-9, Nut Factor Table 8-15).
Notes on Using These Tables
Check units carefully. Most errors in structural calculations come from unit inconsistency. Verify that load units (kN vs N, kPa vs Pa) are carried correctly through every calculation.
Deflection ≠ strength. A beam may pass a deflection limit at a shorter span than its bending capacity permits, or vice versa. Both criteria must be checked independently.
Hydraulic gradients. The pipe flow tables assume the pipe is flowing full. Partially full flow (gravity drainage) requires Manning’s equation or a hydraulic elements chart. For pressurised systems, add head losses at fittings (typically 10–30% additional equivalent length).
Electrical safety. Ampacity tables assume a single circuit in good condition. Overcurrent protection must be rated ≤ the cable ampacity after all derating factors are applied. When in doubt, use the next larger cable size.
Thread lubrication. Tightening torques change significantly with lubrication: dry threads may require 20–30% more torque than oiled threads for the same clamp force; zinc-plated threads are typically between dry and oiled.
Professional review. These tables are for initial sizing, field estimation, and educational use. Life-safety structures (bridges, occupied buildings, pressure vessels) require review by a licensed Chartered Professional Engineer (CPEng) or equivalent.
Generated by
scripts/generate_engineering_tables.py — Recovery
Library Doc #017. Date: 2026-02-20.