Why is my consumer unit making a humming noise – Advice from Electriman, North London Electricians

## Why Is My Consumer Unit Making a Humming Noise?

Hearing a hum from your consumer unit (fuse box) is more common than you might think, but it always deserves attention. Here is what it usually means and what you can safely do about it.

### Most Common Causes

- **Loose busbars or internal connections** — vibration from mains electricity (50 Hz) can cause components to buzz if they are not tight

- **A failing or overloaded MCB (circuit breaker)** — breakers under sustained load can emit a low hum

- **RCD or RCBO humming** — residual current devices sometimes buzz slightly, especially older models

- **Smart meter or surge protection device (SPD)** — these contain small components that can generate a 50 Hz tone

- **Normal mains hum** — a very faint, barely audible hum can be completely normal on modern dual-RCD boards

### What You Can Safely Check

1. **Listen carefully** — is the hum constant or does it change when you switch appliances on or off?

2. **Feel for heat** — carefully place the back of your hand near (not on) the consumer unit casing. Warmth is a warning sign

3. **Smell for burning** — any burning plastic smell means call an electrician straight away

4. **Check the meter tails area** — sometimes the hum originates from the smart meter or its isolator switch, not the consumer unit itself

### When to Call an Electrician

**Call a qualified electrician if:**

- The hum is loud or getting louder over time

- You noti

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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.