Every home and business has a consumer unit. It is an important part of an electrical installation, and there are instances where a consumer unit replacement becomes necessary. Choosing the right consumer unit is important, so if you are thinking about changing consumer units, this blog post covers all the things you need to know.
What is a consumer unit?
A consumer unit, also known as a fuse box, is the central hub of a home’s electrical system. It contains circuit breakers or fuses that protect against overloads and short circuits in your home’s wiring. The mains power passes through the consumer unit and is distributed throughout the house via the various circuits. There are usually multiple circuits originating from the consumer unit, each supplying a certain section of home wiring. If your power cuts out, this is the first place to check, in case a fuse has tripped.
Why do they need to be replaced?
There are various reasons why a consumer unit replacement is necessary. In an older property, the current consumer unit may not be compliant with the latest regulations, or the components are too old to be replaced. It is customary to replace the consumer unit when some or all of the circuits are upgraded in the property, as part of a refurbishment or rewire. Often, replacing parts in an older consumer unit isn’t cost-effective and it is cheaper to replace the entire unit.
How often should a consumer unit be replaced?
There are no set intervals when it comes to replacing consumer units. Most people replace their consumer unit if an EICR report has indicated it should be upgraded or they are having some electrical work done and it makes sense to replace it.
A new consumer unit is also needed if you add an extension to the garage or build a garage or outhouse. It is better to do this than extend existing circuits into new areas of the home.
If new circuits are being set up, they must adhere to the most up-to-date wiring regulations, and it’s frequently the case that an older consumer unit won’t comply with the current requirements and regulations.
The five things to consider:
Before you replace a CU, here are the five main things to consider.
How much does it cost to replace a consumer unit?
The “bare bones” of consumer units are not too expensive. Depending on specification and size, (RCDs/RCBOs/AFDD/SPDs) they can cost anywhere between £150-£350+. The main cost is in the labour to replace the unit, which can be anything from £450 to £800, depending on the work involved and whether the unit is being replaced as part of a wider programme of improvements.
How long does it take to replace a consumer unit?
Replacing a consumer unit is typically a full day’s work. The existing installation and circuits will be tested, and the incoming supply/earthing and main bonding checked. The new consumer unit will be installed, labelled, and tested, then a certificate issued, and Building Control notified.
The type of consumer unit
There are different types of consumer units. The one recommended will depend on the size of property and number of circuits you have and also your budget.
The three main types of consumer units are:
- Dual RCD consumer unit
- Main switch consumer unit – RCBO populated
- High integrity consumer unit – a mix of a dual RCD consumer unit with some circuits on RCBOs
Circuits and circuit separation
As we do not offer further separation of circuits we can improve segregation by RCD or RCBO.
Improvements include:
Dual RCD
In this setup, circuits are covered by 2 RCDs. Where an earth leakage fault develops on a circuit and causes an RCD to trip, the supply is lost to all circuits covered by that RCD. This can result in loss of power and lighting etc in several areas. There is also a higher risk of nuisance tripping in this set up as several appliances across multiple circuits can leak current to earth in normal operation, tripping an RCD.
In the event of a fault, investigation works can be more time consuming as we would first need to identify the circuit that has caused the RCD to trip.
We install A type RCDs/RCBOs & surge protection devices (SPDs) as standard, unlike many other contractors to ensure full compliance with the 18th edition wiring regulations.
RCBO
In this setup, each circuit has individual RCD protection. Therefore, in the event of an earth leakage fault, only that circuit trips. By providing greater sub-division of RCD protection, this setup also avoids unwanted nuisance tripping.
In the event of a fault, investigation works are also far easier as the circuit with the fault will already be identified.
UK Wiring Regulations
UK wiring regulations are there to protect consumers and to ensure a consistent and safe approach to wiring and electrical works. The BS 7671 – 18th Edition – Wiring Regulations are co-published by the BSI and IET. This is the authority all electricians must adhere to when working on electrical installations.
Get in touch with a qualified electrician today
Always work with a certified electrician when replacing a consumer unit. If you need advice or would like a quote, get in touch with us today on 020 4542 1890.
