What Size Cable Do You Need for a 200 Amp Supply?
For a 200 amp main supply, use 70mm² copper cable with PVC insulation under BS 7671 Table 4D1A, rated at 207A clipped direct. Under NEC, 3/0 AWG at 75°C provides 200A per Table 310.16. Under AS/NZS 3008, 50mm² cable suffices at 210A. Aluminium conductors offer a lighter, more economical alternative at this size.
Quick Reference: Cable Size for 200 Amp Main Supply by Standard
| Standard | Cable Size | Conditions | Reference |
|---|---|---|---|
| BS 7671 | 70mm² | Method C or E, PVC insulation | Table 4D1A |
| NEC | 3/0 AWG | THWN-2, 75°C column | Table 310.16 |
| AS/NZS 3008 | 50mm² | Clipped direct, PVC insulation | Table 13 |
| IEC 60364 | 70mm² | Reference method C or E, PVC | Table B.52.4 |
Values shown are for copper conductors in typical domestic/commercial conditions. Actual size depends on installation method, ambient temperature, and cable length. Use our free cable sizing calculator for your exact scenario.
Typical Applications for a 200 Amp Main Supply
- Main incoming supply
- Large commercial building
- Industrial main switchboard
- Multi-storey residential block
Calculate Your Exact Cable Size
These are general guidelines. Your specific installation needs exact calculation accounting for cable route length, installation method, ambient temperature, and cable grouping.
Frequently Asked Questions
Is 70mm² copper necessary for 200 amps?▼
Under BS 7671 with PVC insulation, yes — 50mm² is rated at only 167A clipped direct. With XLPE insulation, 50mm² provides 212A which covers 200A. Aluminium 95mm² is a common cost-effective alternative.
Can I use aluminium cable for 200 amps?▼
Yes. Aluminium is common and cost-effective at 200A. 95mm² aluminium PVC cable is rated at 200A under BS 7671. Aluminium requires larger terminations and bi-metal connectors to prevent galvanic corrosion with copper busbars.
What size cable for a 200 amp three-phase supply?▼
For three-phase 200A, use 70mm² 4-core copper PVC cable or 50mm² 4-core XLPE cable per phase. Three-phase ratings are comparable to single-phase for standard installation methods.
What is 3/0 AWG in mm²?▼
3/0 (000) AWG has a cross-sectional area of 85mm², between 70mm² and 95mm² metric sizes. Its NEC ampacity at 75°C is 200A per Table 310.16, exactly matching the 200A requirement.
Do I need a supply upgrade for 200 amps?▼
Most UK domestic supplies are 60A or 100A. A 200A supply requires DNO approval and typically involves a cut-out upgrade, new meter tails, and potentially a new service cable from the network. Lead times can be 6-12 weeks.
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