Combustible Electrical consumer unit

Combustible Electrical consumer unit

9:40 AM, 7th February 2020, About 3 years ago 15

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Hello All at 118 Property, I have a question, I’m in the process of buying a house to let. The Electrical safety report done in 2017 highlights the Electrical enclosure of the power unit to be of flammable material. the report shows C3, Improvement recommended.

Does this mean that it will fail it’s next test when I get it inspected again? Should I raise this challenge with the seller.

Many thanks for the wonderful informative website and information.


Editors Notes:

A Code 3 means ‘Improvement Recommended’

Something has been identified that does not comply with the latest regulations but isn’t considered dangerous or present immediate or potential danger. However, it would result in a significant safety improvement if remedied. One code C3 on its own should not warrant an overall unsatisfactory report.


Neil Patterson View Profile

9:42 AM, 7th February 2020, About 3 years ago

Please see my notes above on C3 meaning.


10:23 AM, 7th February 2020, About 3 years ago

If it were the case that plastic consumer consumer Units had to be replaced with the new 18th edition standards which specifies metal enclosures then nearly every domestic property in the country would have to be upgraded. This clearly is not the intent of the new regulations . If the consumer unit was fitted before the standard was enforced at the end of 2018 then older versions of the wiring regulations would have applied and these were and remain perfectly adequate standards. So there is no need to require that the consumer unit is changed. It is purely advisable. The only exception is if the consumer unit is fitted under the stairs and there is no adequate fire restraint fitted to delay a fire from spreading and preventing escape using the stairway. Even then a non combustible deflector can be fitted above the unit rather than change to a metal housing CU.

Rob Crawford

11:24 AM, 7th February 2020, About 3 years ago

As explained previously it's not a legal requirement, however, if you intend to change it, the best time would be at the next test and inspection in 2022. This would be cheaper for you.

Rob Crawford

11:26 AM, 7th February 2020, About 3 years ago

As explained previously it's not a legal requirement, however, if you intend to change it, the best time would be at the next test and inspection in 2022. This would be cheaper for you. I am assuming 17th edition safety checks are confirmed as acceptable under the new legislation.

Paul landlord

11:42 AM, 8th February 2020, About 3 years ago

I'm a registered electrician as well as a landlord.

I regularly write EICRs for people with a string of C3s on the 'satisfactory' (or pass if you prefer) report.

C3s are often raised because of forever changing regulations and not because the installation is unsafe. It just means a situation is in place where you couldnt install something in that way today (current regs) but it was installed in accordance with the regs in place at the time.

We electricians were installing plastic consumer units in December 2015 in the full knowledge that under BS7671 2015 Ammendment 3 then from jan 16 these would pick up a C3 when the metal consumer unit reg became mandatory (6 months behind the other amm3 regs becoming mandatory as the new regs process is shambolic).

New regs are very rarely retrospective (if the installation was put in place to the regs of the day and it has not deteriorated or its integrity been compromised it is satisfactory and attracts a C3. There are still plenty of 1960s-80s rewireable fuseboards out there 'satisfactory' but with a C3. These have no RCD protection either but coding is a C3!!

If you want to change it then do- I wouldnt- but be prepared also to cost in a type2 spd (18th edition that came enforceable jan19). And also do it before 2022 when AFDDs are planned to become mandatory under Amm2 (amm1 came out 5 days ago now after the 18th edition only became mandatory a year ago!) else it will cost you a VERY hefty sum.

Hope this provides an insight into the ridiculous world of electrics as well as answering your question.

Paul landlord

11:58 AM, 8th February 2020, About 3 years ago

Reply to the comment left by Porky at 07/02/2020 - 10:23
Although your intentions are good and the majority of your information is correct which I give you full credit for, I respectfully submit you have also given some incorrect advice that will have some readers running scared.

Just to be picky it was BS7671 2015 amm3 that brought in metal consumer units recommended from jan2015 but not enforceable till jan 16. Nothing to do with the 18th edition that came enforceable 2019.

More importantly this plastic consumer units unders stairs business etc is TOTALLY wrong so fellow landlords dont panic.

There is nothing in the regs about this at all, although in this instance a board change may be advisable depending on how you personally view risk- no obligation for changing or 'deflection plates'.

Personally in such a circumstance an extra smoke detector there (hard wired, battery backed up and interlinked with your other detectors) is my choice. If you rely on battery stand alone smokes then this is redundant of course.

Hope this clarifies things for readers.

I am a registered sparks by the way charged with sifting through and keeping up with regs, their implications and retrospective (or not) effect.


18:10 PM, 8th February 2020, About 3 years ago

I am not a Sparky but a landlord who has upgraded to many plastic consumer boards in recent years.

Having had occasion to discuss a house fire with the local Fire Service they quite openly told me of the problems with the fire resistant plastic consumer units and how the metal units are not a source of combustion. That's why the move to metal in the latest regulations. The plastic ones are fire resistant but not fire proof and plastic will eventually go up in flames.

No one is talking also about the consequences of replacement meters on supply boards. The installers push and pull the consumer unit wires but only check the security of those wires to the meter end not the consumer end. So the wires can wobble in the consumer unit repeatedly short, over heat, wire insulation eventually catches fire and sometimes the plastic consumer unit too, it becomes a source of combustible material. But not with metal consumer units. Is this the real reason the regs changed to metal?

Paul landlord

0:33 AM, 9th February 2020, About 3 years ago

Reply to the comment left by at 08/02/2020 - 18:10
To the 2nd part of your comment The cynical amongst us in the trade say - 'YES'. I've been in the sparks business for many years and consumer fires were never really a big issue if fitted correctly and maintained (as in the eicr periodically as we as landlords are finally being forced into).

These smart meter fitters etc in my experience want to be in and out as soon as they can, 'rag around' the consumer unit tails without care causing them to come loose into their connection in the board (bear in mind your looking at a 7mm length of 25mm (cross sectional area) round copper in a square containment- thats never been a great set up but thats what we have.

This will loosen the connections (loose wires cause fires- cliche but true). Loose connections= high resistance = overheating and potential fires- yourcprotective devices inside any board are plastic (whether a metal board or a pladtic one). The chances of shorting etc arent likely but loose connections are.

The meter fitters are not permitted to go into the consumer unit even if they wanted. Its where the boundary lines are drawn between them and us.

That said metal boards are obviously still a massive safety improvement. Plus you would normally have a 'gland' that secures the meter tails on entry so there is no chance of the tails being loosened inside the board regardless of agressive treatment of the tails from outside. So its a double whammy win.

That said even though on my report I am the voice of BS7671 and say recommended improvement- i cant say anything else- I always verbally tell my customers (and id deny it if asked) that I wouldn't recommend it.

Plastic boards are not a problem if the installation is properly maintained. We have 100s of 1000s of them fitted throughout the country and were fitting them since the 80s with bo big issue until the constant mucking about of meters that we have now (oh and the diy installers of consimer units too of course). But hey 'electrics is easy int it Put a wire here and there and it works '. Big difference between working and safe tho that is a fact!


8:23 AM, 9th February 2020, About 3 years ago

Thanks Paul, I am glad a professional electrician agrees.

Michael Barnes

18:56 PM, 9th February 2020, About 3 years ago

With a C3 there is no problem with safety, and there is no reason it should fail the next inspection.
However, there may be a problem in a let property if the "Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020" go through unamended (see
Today I have became aware of the "Joint Committee on Statutory Instruments" at
I don't know if it is too late to send them your concerns over the proposed regulations.

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