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Consumer units


This information is provided to help you make your mind up on when you need our services. Please read through and then contact us if you need any further help.


Does my consumer unit need to be metal.

In 2016 the regulations changed and now all domestic consumer unit must be made of non combustible materials or housed in a box made of non-combustible materials.  

This change was made to prevent house fires metal consumer units achieve this by preventing the escape of fire from the unit to the rest of the house. 

Should I change my plastic consumer unit?

If you have an old plastic consumer unit and the unit contains modern RCBO's that are contained within non-combustible materials that have been updated from the old style MCB's. 

Technically the consumer unit can remain in the property.

Is it illegal to have a plastic consumer unit?

You can fit a plastic consumer unit and as long as it is housed inside a non-combustible material it meets the regulations. Though if you are going to fit a plastic unit and pay for the changes. It would cost less to just fit the modern version.

Can I have more than one consumer unit?

If you plan to improve your property rather than move you may be considering installing a second consumer unit.

Your consumer unit can only fit a certain number of MCB's and supply a certain amount of power before becoming a hazard and potentially causing an insurance risk.

If you wish to get a second consumer unit you must get it installed by a registered competent person to the current regulations

Can my consumer unit be moved?

Simple answer, Yes.

You can get your consumer unit moved as long as the work is carried out by a qualified electrician. 

However whether the current unit can be re-used is another question.

This will depend on many of the questions answered in other sections of this page.

If you wish to move the consumer unit within 3m of the meter this will be a relatively simple job. 


Any further than 3m can lead to additional work or items being required.

If you wish to move it to another room or part of the house you may find that you have to contact your supplier and check on their costing for moving your main incoming supply.

Surge Protective Devices (SPD).

Surge Protective Devices (SPD)protect a property from Transient Overvoltages.

They protect all the seisitive equipment in your property. Equipment such as computers, lighting TV's etc. All the items that you care about and don't want damaged.


The surge can cause all this equipment to become damaged.

SPD's are most commonly installed in your consumer unit to protect all items connected to the unit. 

 You may wish to consider installing different methods of protection additionally to protect other services.

SPD's come in three types,

  • Type 1 installed at the origin of the install.

  • Type 2 Installed at the distribution board )most common in domestic installations). Combined Type 1 and 2 units can be installed.

  • Type 3 Installed near to the device to be protected (Only used as an addition to Type 2).


What is a Transient Overvoltage


These are surges of electricity from other means from man made or natural causes. 

How do they occur?


Natural TOV's occur when lightning strikes an overhead cable near to your property.


Man made TOV's occur when Transformwers or motors switch and cause a surge. More common now due to the install of extra devices into the home such as EV Car chargers, air source heat pumps and  some washinbg machines etc 

Do I have to have one?

BS7671 states that if you do not have one then a risk assessment must be carried out if it not provided if any of the following apply from TOV's

  • Result in serious injury to, or loss of, human life; or

  • Result in interruption of public services and/or damage to cultural heritage; or

  • Result in interruption of commercial or industrial activity; or

  • Affect a large number of co-located individuals.

This includes domestic properties.

So the short answer is yes if you are having  new consumer unit installed it is within the regulations to have SPD's fitted.

It is ultimately your decision as the customer but the risk to your property and your devices make it the sensible thing to do.

Some insurance companies will not pay-out if they state within your policy that an SPD must be fitted.

Ready to go??

When you feel you have enough information you can contact AEM and we will Help you to fit your new modern and safe consumer unit which adheres to all the relevant regulations contained within the current version of BS7671.

Just give us a call or  Email.


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