Before replacing a consumer unit, it is worth noting that an old fuse box is neither illegal nor inherently dangerous. Industry standards are changing all the time and an older fuse box likely met the relevant standards when it was installed. As long as you are safe and the fuse box is still capable of meeting your energy needs, there is no need to worry about an upgrade.
Having said that, just because you don’t need to worry about an upgrade doesn’t mean you shouldn’t consider it. Consumer units are a lot better at protecting us than their older counterparts.
In this guide, we cover:
- The difference between a fuse box and a consumer unit
- Signs to look out for that indicate you should replace it
- The process of replacing a consumer unit
- The regulations that affect the job
- Frequently asked questions about replacing a consumer unit
What is the difference between a fuse box and a consumer unit?
A consumer unit and a fuse box are technically the same. They both refer to the device responsible for controlling and distributing energy throughout the house and protecting the residents from electrical failure. A consumer unit is simply the modern equivalent of a fuse box.
That said, there are two, key differences.
When a fuse box ‘trips’, the fault or overload current flows through the fuse wire causing it to become hot and melt. The melted fuse breaks the circuit and disconnects the energy supply. A consumer unit, on the other hand, uses circuit breakers. These are automatic protection devices that switch off a circuit if they detect a fault.
The first difference concerns the restoration of power. A consumer unit simply requires you to switch the power back on, while a fuse box requires you to replace the melted fuse before the power can be restored.
The second difference is the level of protection. Fuses take one or two seconds to break a circuit compared to a consumer unit which takes milliseconds – the length of time before the risk of electrical shock is present.
Do I need to replace my consumer unit?
A fuse box only needs to be replaced if it poses a danger to your health and safety. If you’re concerned or unsure, arrange for an electrician to come out and check your installation. Our guide on Electrical Installation Condition Reports will tell you what you need to know.
However, we’ve drawn up a list of things to look out for and consider:
- You have a fuse box instead of a consumer unit: A fuse box is simply the older version of a consumer unit. The key difference is that a fuse box uses fuses instead of circuit breakers. So, when a fault occurs, the fuse wire melts to break the circuit and prevent harm. This process takes longer than a circuit breaker (which consumer units have) and requires the melted fuse to be replaced before the power can be restored. Most fuse boxes are no longer compliant with safety standards or suitable for modern life.
- Your consumer unit is more than 10 years old: Consumer units become worn and ineffective with time and use, so it’s always worth checking how yours is coping. What’s more, regulations on electrical safety are changing all the time so there’s a chance your unit isn’t compliant. While this isn’t a reason to change it, it does mean that it may not be the safest option available to you.
- Your consumer unit doesn’t have RCDs: Residual current devices are life-saving devices designed to protect against fatal electric shocks or fire. The IET regulations require most, if not all, circuits in domestic premises to be RCD protected.
- There is visible damage or deterioration on your unit.
- Your unit keeps tripping.
- Your lights are flickering or your sockets are unresponsive.
- You’re having major work done (e.g. a full-house rewiring).
If you notice one or more of these, it is a good idea to organise an inspection. There’s no harm in being cautious
The fact is, consumer units are a lot better at protecting us than their older counterparts. Not only are they designed using modern technology, but they’re subject to updated industry standards which require further protective measures. Under the IET Wiring Regulations BS761:2018, new consumer units are required to:
- Be manufactured from non-combustible material: All new electrical installations must have a metal-clad consumer unit or metal-clad casing. The purpose of this is fire safety. Metal is better at containing a fire, minimising the spread of fire and removing any additional source of fuel for the fire (e.g. plastic).
- Have additional protection through a Residual Current Device (RCDs): RCDs are specifically designed to protect people from electrical shock and are thousands of times more sensitive than circuit-breakers or fuses.
Fuse boxes do not have RCDs and many are made out of plastic. An upgrade is therefore a long-term investment that will pay for itself in value.