A Guide to

Consumer Units

Replacing Fuseboxes and Consumer Units in Domestic Premises

Fuseboxes, also known as consumer units, are replaced for numerous reasons.

Consumer units are most often replaced as part of a refurbishment where new circuits are required and when connecting to the existing consumer unit which might not meet the latest electrical regulations. It could be that there is no space capacity in the existing consumer unit to connect the new circuits.

It also may be that the replacement has been a recommendation following an electrical inspection, or it possibly could be that the existing consumer unit has been damaged requiring a distress change. The important thing is to understand what’s involved.

J.S Electics demonstrates competence by holding the necessary insurances as well as having the right procedures to assure compliance within our work. This means that we can provide you with the necessary certificates to demonstrate the regulatory compliance of the work we do.

Understanding Modern Consumer Units

From 1st January 2016, it has become mandatory for any consumer units installed or replaced in domestic premises to be made of, or enclosed by, a non-combustible material. Which means it is likely that a steel consumer unit will be used.

Modern consumer units come with various configurations of protective devices and J.S Electrics will be able to give you the best options suited to your installation and budget.

All domestic consumer units will have a main switch and miniature circuit breakers (MCBs) as well as residual currents devices (RCDs/ RCBOs).

It is important to understand that compared to older set-ups like fuseboxes, modern devices such as RCDs are designed to detect earth faults, can detect existing circuit faults and can switch off any electrical circuit if a dangerous situation arises.

It’s not uncommon for an existing installation to have underlying faults not picked up by an old fusebox. Therefore, if there were any underlying issues within an existing installation they need to be found prior to the consumer unit being replaced. If not, then it is likely that the RCD would detect the issue and switch off, leading to an unsatisfactory situation for you and the electrician since you would have no power and the electrician would not be able to issue the correct completion certification without first addressing the issue.

Are There Any Checks to be Made Prior to Fitting a New Consumer Unit?

Yes, replacing a consumer unit is classed as making an alteration and therefore falls into the category of new work. Electrical Regulations require existing equipment that must be adequate for the alteration, as well as the earthing and bonding.

What is the Recommended Best Practice?

Prior to the consumer unit being replaced, an Electrical Installation Condition Report (EICR) should be carried out. This provides a summary of the condition of the installation allowing a decision to be made on how to proceed with the planned consumer unit change.

The report would give details of any observations classed as being immediately or potentially dangerous or requiring further investigation. The report would also list any recommendations noted during the inspection.

What If I Choose Not to Have an EICR Carried Out?

As a company, we should be given sufficient time to carry out visual checks as well as essential tests. This is known as a pre-work survey and will provide limited information on the installation. This would involve your power being switched off for a short period.

Whilst this method should indicate the suitability of the installation for the consumer unit replacement, it will not be as conclusive as an EICR.

You should be aware that following the consumer unit replacement, during final inspection and testing, if any observations classed as being immediately or potentially dangerous, or requiring further investigation are found, then those circuits will not be reconnected.

What Paperwork Should I Expect to Receive?

Replacing a consumer unit is classed as new work and therefore will require an Electrical Installation Certificate to be issued, and this would also require a Building Control Compliance Certificate, which you will receive from NAPIT.

By choosing J.S Electrics, you will be issued with the correct compliance certificates which you may need should you come to sell or rent your home.

Source: NAPIT


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J.S Electrics (JSE) Ltd, 6 Sterling House, Oldbury Road, Cwmbran, NP44 3JU

Registered in England & Wales, registration number 13031093. 

Registered address; 6 New Street, Pontnewydd, Cwmbran NP44 1EE.


01633 530765 / 07368 195 091