Why is my consumer unit hot?

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. Check for a burning smell — this is a red flag regardless of temperature. Listen for buzzing or crackling sounds coming from the unit. When to Call an Electrician Call a Part P registered electrician immediately if: The unit is hot enough to be uncomfortable to touch You can smell burning or see scorch marks Breakers are tripping more frequently than usual The main switch feels hot Do not open the consumer unit yourself. Even with the main switch off, the cables entering from the meter remain live at all times. This is work for a qualified electrician only.