Why is my consumer unit hot – Advice from Electriman, North London Electricians

Why Is My Consumer Unit Hot?

It's completely normal for a consumer unit (fuse box) to feel slightly warm during periods of heavy electrical use — this is just heat generated by current flowing through the breakers. However, if it feels genuinely hot to the touch, is discoloured, or you can smell burning plastic, this is a warning sign that needs urgent attention.

What Could Be Causing It?

Loose connections — the most common cause. A slightly loose terminal causes electrical resistance, which generates heat. Over time this can cause arcing and fire.

Overloaded circuits — running too many high-draw appliances (electric showers, ovens, heat pumps) can push breakers beyond their rated capacity.

Faulty or aging circuit breakers — breakers degrade over time and can run hot even under normal loads.

Undersized cable — if cables feeding circuits are too small for the load, they'll heat up at connection points inside the unit.

Poor quality consumer unit — some older or non-certified units have inferior busbars and components that run hot.

High ambient temperature — a unit installed in a boiler cupboard or south-facing location may retain more heat.

What You Can Safely Check

Feel the outside of the cover with the back of your hand. Warm = probably fine. Hot = get help.

Look for discolouration around the cover edges or trunking without opening anything.

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Electriman covers Mill Hill, Barnet, Finchley, Edgware, Enfield, Watford and surrounding areas. All work is Part P certified and fully insured.