Why does my neutral conductor at the fuse box show a temperature of 80°C?

Finding a neutral conductor running at 80°C at your consumer unit is a genuine warning sign that something is wrong, and it deserves prompt attention. Here is what it means in plain terms and what you should do. What the neutral conductor does Every circuit in your home has three wires: a live (brown), a neutral (blue), and an earth (green and yellow). The neutral carries current back to the supply after it has passed through your appliances. Under normal conditions it should run at close to room temperature, or only slightly warm if the circuit is heavily loaded. Why it gets hot The most common reason is a loose connection at the terminal inside the consumer unit. When a terminal is not tight, current has to jump a tiny gap, and that creates resistance. Resistance turns electrical energy into heat. The hotter it gets, the more the surrounding plastic and insulation degrades, which makes the resistance worse, which makes it hotter still. Left alone, this cycle can lead to a fire. Other reasons include: A corroded terminal that has built up a layer of oxide, which acts in the same way as a loose connection. A conductor that is too small for the current it is carrying, meaning the wire itself cannot handle the load without heating up. A high neutral current caused by a fault or imbalance on a three-phase supply if your property has one. What you can safely do right now You can check whether any circuits feel unusually warm at their sockets or switches, and whether any appliances have been running continuously on the affected circuit. You can also reduce the load by switching off non-essential appliances. What you must not do Do not open the consumer unit yourself. The terminals inside can carry lethal voltage even with the main switch off, because the incoming supply cables from your meter remain live at all times. This is work for a qualified electrician. When to call an electrician You should call a Part P registered electrician today. An 80°C reading is already well above safe operating temperature for standard 70°C-rated PVC insulation. If the conductor or its insulation feels or smells burnt, or if you can see any discolouration, treat it as an emergency and call immediately. In an emergency you can also contact your Distribution Network Operator (DNO) to isolate the supply.