How Do I Know if My Old Fuse Box Needs Replacing? | Resistance Electrical

If your fuse box still has fuses you rewire by hand, has no RCD, or keeps blowing a fuse or tripping when the heating, kettle and oven are all on, it is probably due for replacement. An RCD, or residual current device, is the switch that cuts the power in a split second if electricity starts leaking to earth, for example through a damaged cable or a person. Many older fuse boxes were fitted before RCDs became standard, so they don't have one at all.

This post covers the signs that matter, the checks you can safely make yourself, and what replacing a fuse box involves. You can look at your fuse box and press its test button, but never take the cover off. Everything behind the cover is live.

Fuse box or consumer unit?

They are the same thing. "Consumer unit" is the modern name for the box that takes the electricity coming into your home and splits it into separate circuits, such as sockets, lights, the cooker and the shower. Each circuit has its own protection, either an old-style fuse or a modern circuit breaker, which switches off if that circuit is overloaded or develops a fault.

What changes over time is the protection inside. A unit from the 1970s or 1980s and one fitted last year both do the same basic job, but the newer one protects you in more ways.

Signs your fuse box is due for an upgrade

Look out for any of these:

• Rewireable fuses. Small white or brown carriers with a piece of fuse wire inside, which you replace by hand when it blows. These were common until the 1980s.

• No RCD. On a modern unit you will see at least one switch marked with a small "T" or "Test" button. If there is no test button anywhere, there is probably no RCD protection.

• A wooden backboard, a cast-iron switch or a mix of old fuses. These point to an installation that is several decades old.

• Signs of heat. Scorch marks, a burning smell, crackling or buzzing, or a unit that feels warm. Treat these as urgent.

• Frequent trips with no obvious cause, especially now that heaters and tumble dryers are back on for the winter.

• A plastic unit. Since January 2016, new consumer units in homes have had to be made of non-combustible material, usually steel, after a rise in house fires starting in consumer units, often from a loose connection overheating. It matters most where the unit sits under the stairs or in a hallway you'd use to get out.

An old fuse box isn't automatically dangerous, and the wiring regulations aren't backdated, so there's no rule that says yours must be replaced by a certain date. But the more of these signs you can tick, the stronger the case for an upgrade.

Safe checks you can make at home

You can do all of these without opening anything:

1. Look at the front of the unit. Note whether you have fuses or switches, and whether any switch has a test button.

2. Press the test button on each RCD, if you have one. It should switch off straight away. Switch it back on. If it doesn't trip, or won't reset, it needs looking at.

3. Check the labels. Every switch or fuse should say which circuit it controls. Missing or wrong labels make faults slower to find.

4. Use your nose and ears. A burning smell, buzzing or crackling means switch off at the main switch if it's safe to reach, and call an electrician.

Don't remove the cover, change a fuse carrier for a bigger one, or tape a switch on to stop it tripping. A switch that trips is doing its job. If one keeps going off, our guide on what to check when your RCD keeps tripping walks you through a safe reset.

When an upgrade is worth doing anyway

Some jobs are a natural time to replace an older unit, even if it isn't showing any of the signs above:

• Adding a big new load, such as an electric car charger, an electric shower, an induction hob or a heat pump. An older unit may not have space for a new circuit, or the protection the new circuit needs.

• Fitting solar panels or a home battery, which need their own protected connection at the consumer unit.

• After an electrical safety check that has flagged the unit as needing improvement.

• Renovating a kitchen or extension, when new circuits are going in anyway.

What happens when we replace a fuse box

A consumer unit replacement is a job for a registered electrician. It counts as notifiable work under Part P of the Building Regulations in England and Wales, which means it must be either signed off by an electrician registered with an approved scheme or inspected by building control.

On the day, the power to the whole house is off for most of the job, often several hours, so plan to be without heating controls, the internet and the fridge for that time. The electrician checks the earthing and bonding (the connections that carry a fault safely away), fits the new unit with the right protection for each circuit, then tests every circuit before switching back on.

Testing sometimes turns up an existing fault on a circuit that the old fuse box was never sensitive enough to notice. That isn't the new unit causing a problem. It's the new unit doing what it should, and the fault needs fixing before that circuit goes back into use.

When it's finished, you should receive an Electrical Installation Certificate, and a Building Regulations compliance certificate follows from the electrician's registration scheme. Keep both with your house papers. You'll be asked for them when you sell.

If you rent out a property

Private landlords in England must have the electrics in a rented home inspected at least every five years. If the report finds anything dangerous or potentially dangerous, including on the consumer unit, it must be put right within 28 days, or sooner if the report says so. Our electrical testing and inspection service covers these reports for landlords and homeowners.

Getting your fuse box checked

If you’re unsure about your fuse box, Resistance Electrical can inspect it and tell you plainly whether it needs replacing now or can safely wait, and why. We’re NAPIT registered for Part P work, so we can sign off and notify the job ourselves, with no need for a separate inspection from building control. Find out more about our consumer unit upgrade and replacement service.

Worried about your fuse box? Call Resistance Electrical on 07935923323 to book an inspection or get a quote.