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Min. Cable Size for Voltage Drop:0 mm²

Calculated Voltage Drop:(11.5V Max Allowed)0.00 V

WARNING: This tool calculates VOLTAGE DROP ONLY for standard twin & earth flat multicore cables. It does not account for external factors like installation method (in insulation, buried in ground), grouping factors, or ambient temperatures, which can severely reduce cable carrying capacity. Always consult BS 7671 or a qualified electrician.

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Frequently Asked Questions

Why does cable size matter?

All copper wires have electrical resistance. The longer the wire, the higher the resistance. If a cable is too thin for a long run, the voltage will drop dangerously before it reaches your appliance, causing lights to dim, motors to burn out, and excessive heat that can cause fires.

What is voltage drop?

Voltage drop is the amount of electrical energy lost as heat as current travels along a wire. BS 7671 (The Wiring Regulations) dictates that this drop must not exceed 3% for lighting circuits and 5% for power circuits to remain safe.

What size cable do I need for sockets?

In the UK, a standard 32A ring main for plug sockets is wired using 2.5mm² twin and earth cable. However, very long runs or cables buried deep in thermal insulation may require 4.0mm² cable to counteract heat buildup.

What size cable do I need for an electric cooker?

A standard domestic electric oven and hob usually pull around 32A or 40A, meaning they typically require a dedicated 6.0mm² or 10.0mm² radial circuit run directly from the consumer unit, depending on the distance.