Landlord electrical safety certificate

Have you never found a consumer unit with signs of overheating? It’s hardly a unknown issue and usually gets repaired whatever the enclosure is made of, but some do have to be replaced, however as yet I have not had to replace a consumer unit with a metal enclosure because of overheating, but I have replaced a considerable number of consumer units with plastic enclosures due to overheating issues.


If you open a consumer unit and there’s a plastic stalagmite hanging down in side it, it’s probably a risk utter regardless of where it is located, but more so in an escape route or under the stairs.


Andy B.

The IET guidance is a little vague. It suggests "sealing" around all cable entries, although the regulations only require IP2x, or IP4x on the upper surface. Sealing is also needed, if you are going to do it as a fire prevention measure around the lid, and the MCB cover. Unless you keep all air out, sealing does almost no good at all! I don't know who wrote the "guidance", but I have yet to see it fully followed, because it makes the CU unusable! Perhaps the manufacturers should provide seals around the lid and cover, or perhaps intumescent seals would be better.

Grumpy

I outlined why plastic consumer units are not inherently unsafe above. The problem really is that Sparkingchip and one or two other posts seem to dispute this. The regulations themselves in Section 6 make it very clear that non-dangerous items and installations to previous editions are permitted for continued use. The problem of the London fires and the solution is possibly not the best way to deal with the problem. This problem is exactly the same throughout the Electrical industry, loose connections ARE inherently dangerous, be it in DNO cables or consumer appliances. As there is no difference between the connections in a metal or plastic CU, both rely completely on tight connections, and there is probably no difference in their ability to catch fire in the bigger scheme of things. There is a bit more inflammable material in a plastic one, and fireproof enclosure means one which is sealed to the air (ATEX) so that things simply cannot burn, however hot they get. A fire can certainly start in a metal CU, burn the MCBs, etc. and all the cables giving off a great deal of heat. Whether this starts a fire is largely a case of luck, if it is all contained in a concrete room with a metal door, then probably not, if under a wooden staircase, perhaps. I have yet to see any non-inflammable enclosure around a CU (meaning: fully sealed) and no inflammable material being used. A wooden framed cement fibre box with gaps around the joints and door is clearly useless. It may delay the fire, but unless there is a fire alarm sensor, does little good in the long term. There will not be a fire if all the terminals are tight, and this is part of an EICR, showing that they might be a good idea. Remember that to burn a fire needs a large supply of oxygen. Take this away and nothing much will happen. Burning takes roughly the same weight of oxygen as of the fuel material, so about 5 times the weight of air. That really is quite a lot!

In Andy's Fire Brigade Black Museum above, the section https://www.esfrs.org/black-museum/all-the-black-museum-cases/faulty-electrical-intake/   showsa fair few cut-outs where they have been the cause of fire.


Within that section is a link to a report: https://www.esfrs.org/EasySiteWeb/GatewayLink.aspx?alId=754 the statistics within and the numerous photographs make serious reading. And beg the question, who by and how often are cut-out terminals and fuse holders checked for termination tightness and low resistance joints/contact?

Clive

Over the years I have done a lot of testing of plastic consumer units to see how flammable they are.


It’s not difficult and does not require the destruction of a complete consumer unit, next time you need to get a new cable into a plastic consumer unit enclosure take the cable entry blank you have removed and holding it in your long nosed pliers put a lighted match or cigarette lighter under it to see what happens. The result can be quite scary, particularly as you are only igniting a relatively small piece of plastic.


Plastic consumer unit enclosures are not inherently dangerous, but do have the potential to be highly dangerous.


The location of the consumer unit does need to be taken into consideration if it has a plastic enclosure, if it’s enclosed in a non-combustible cupboard then it complies with the current edition of the Regulations, if it is in the escape route from someone’ home and showing signs of overheating heating then it’s a serious problem.


We cannot code a consumer without even seeing it. Indeed it may not even be worth mentioning on the report, other than as an rear end covering exercise.


 Andy Betteridge