Is a buzzing light switch dangerous?

A faint hum from a dimmer can be normal. A loud buzz, crackling, heat or a burning smell is not, so switch off and call an electrician.

Why does my dimmer buzz with LED bulbs?

Many older dimmers are not designed for LED bulbs. Fitting a dimmer that matches the bulbs, and dimmable LEDs, usually stops it.

Can a loose connection make a switch buzz?

Yes. A loose terminal can arc, which causes buzzing and heat. This needs fixing straight away.

Should I replace the switch myself?

Replacing switches means working with mains wiring. Use a registered electrician, who will also check the connections and the circuit.

What is a consumer unit?

By Azzeddine Kebbi, NAPIT-registered electrician and director of Kebbi Electrical Services · Updated 10 November 2026

A consumer unit is the box that splits the electricity coming into your home into separate circuits and protects each one. Most people call it the fuse box or fuse board. It is usually under the stairs, in a hallway cupboard or in the garage.

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What is inside

Main switch

Turns off the electricity to all circuits in the home.

RCDs or RCBOs

Switch off fast if current leaks to earth, for example through a person. This is your shock protection.

Circuit breakers (MCBs)

One per circuit. They trip if a circuit is overloaded or has a short circuit.

Old rewireable fuses

Found in older boards. A thin fuse wire melts on overload, with no shock protection.

Signs yours is out of date

Rewireable fuses instead of switches.
No RCD protection, or only some circuits protected.
A plastic consumer unit, or one mounted on a wooden board.
Scorch marks, a burning smell, or breakers that feel warm.

Since 2016, new consumer units in homes must have a non-combustible enclosure, usually metal.

What you can safely do

Reset a tripped switch by pushing it back up. If it trips again straight away, leave it off.
Use the main switch to turn everything off in an emergency.
Do not take the cover off. Work inside a consumer unit is for a registered electrician.

Fire-damaged consumer unit found by Kebbi Electrical on an emergency call-out in Bristol — A burnt consumer unit we were called out to in Bristol. Scorching like this means switch off and call an electrician.

Common questions

Is a consumer unit the same as a fuse box?

Yes. Consumer unit is the technical name. Fuse box and fuse board mean the same thing.

What does a consumer unit do?

It takes the supply from your meter, splits it into circuits such as lights, sockets and cooker, and protects each one with breakers and RCDs.

How long does a consumer unit last?

There is no fixed lifespan. Many boards last decades, but older ones often lack RCD protection and need upgrading. An EICR will show whether yours is still suitable.

Does replacing a consumer unit need a certificate?

Yes. It is notifiable work under Part P, so use a registered electrician who will issue an Electrical Installation Certificate and notify building control. See what is a Part P certificate.

Related guides

Does my fuse board need replacing?

Signs your consumer unit is due an upgrade.

RCBO consumer unit: is it worth it?

How an RCBO board compares with a dual RCD board.

RCD keeps tripping

Why it happens and how to find the cause.

Is your fuse board due an upgrade?

We replace and certify consumer units across Bristol. See our consumer unit upgrades.

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