Why is my consumer unit making crackling noises at night?

Why Is My Consumer Unit Making Crackling Noises? Hearing crackling, clicking, or popping sounds coming from your fuse box (consumer unit) — especially at night — is understandably alarming. Here's what's likely happening and what you should do. Most Common Causes Loose or corroded connections — The most serious cause. When a terminal is loose, electricity can arc (jump) across the gap, creating a crackling sound and generating heat. This is a fire hazard. Thermal expansion — Plastic enclosures, cables, and busbars expand and contract as they heat up during the day and cool at night. This can cause harmless ticking or clicking sounds. Failing MCB or RCD — Ageing breakers can develop internal faults that cause intermittent noise, especially under load in the evening when appliances are running. Overloaded circuit — Too many appliances on one circuit can cause the wiring and breakers to run warm, producing noise as they cool after midnight. Rodent or pest damage — Occasionally, gnawed insulation inside the unit can expose conductors and cause arcing. What You Can Safely Check (Without Opening the Unit) Listen carefully — Is it a regular tick (likely thermal) or an irregular crackle/spit (likely arcing)? Check the time — If it only happens as heating systems switch off at night, thermal movement is more likely. Look for signs of burning — A burning smell, scorch marks around the consumer unit cover, or discoloured plastic are serious warning signs. Check if a circuit breaker has tripped — A tripping breaker alongside noise points to a fault on that circuit. ⚠️ When to Act Immediately Call a Part P registered electrician urgently if you notice: Burning smell or visible scorch marks Crackling that is loud, irregular, or getting worse Any breaker repeatedly tripping The consumer unit feels warm to the touch Do not open the consumer unit yourself. The busbars inside are live even when individual breakers are switched off. This is work for a qualified electrician only.