Can I use a 1.5mm cable for a 16-amp cooker circuit if the run is under 20 metres – Advice from Electriman, North London Electricians

It is completely understandable to wonder whether a shorter cable run means you can use a thinner cable. Unfortunately, the answer is no, and the length of the run is not the main issue here.

The real problem is the current-carrying capacity of 1.5mm cable. Every cable has a maximum amount of electrical current it can safely carry before it starts to overheat. For 1.5mm twin and earth cable, that limit is around 13.5 amps in ideal conditions, such as clipped to a surface with good airflow around it. If the cable is run through insulation, inside a wall, or bundled with other cables, that rating drops even further, sometimes below 10 amps.

A 16-amp circuit demands more than 1.5mm can safely deliver in those real-world conditions. Using undersized cable means the cable will run hotter than it should. Over time, this degrades the insulation, creates a fire risk inside your walls, and could cause the cable to fail entirely.

The distance matters for voltage drop, not for the current-carrying limit. Even on a very short run, 1.5mm cannot safely handle 16 amps under the installation conditions found in most homes.

For a cooker circuit, here is what you need to know:

1. Most standard cooker circuits require 2.5mm cable as a minimum, protected by a 16-amp or 20-amp circuit breaker.

2. Larger range cookers, typically rated above 7kW, will usually need 6mm or even 10mm cable.

3. The circuit must be a dedicated radial circuit from th

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