Consumer Units

[Matt]

Following on from this topic it was mentioned by @Dyson about the number of fires that seem to centre around the consumer unit of a property.  

I have noticed quite a few of these this year posted by station on social media, is there a pattern to it?  Anyone has any on their patch?

[Dyson]

Hi  

So, i reckon, of the top of my head, out of the most 10 recent property fires I've attended, 4 or 5 of them involved consumer units. From memory, over the previous 20 or so years going to fires, probably about 4 or 5 of them were stated in consumer units.  This seems very disproportional, and had got me thinking. These were not in the main old units, I'm talking about fairly new equipment. 

 

[Keith]

Very strange Dyson, were they down to faulty equipment or poor installation?

As an ex spark, I'm very surprised over the years how few fires are actually down to either the consumer unit or the wiring, given the state some of it is in. There must be thousands of properties out there were the electrically wiring is probably still the original installation from the 1960's or 70's. Majority of electrical fires are down to the usual suspects of appliance defects, overloaded sockets and more recently cheap chargers.

 

[Dyson]

Well Keith, i don't know  .....because the units and surrounding wiring are destroyed. So assumptions have to made by the FI guys who come on. To be honest its only now there is an apparent possible pattern that I'm paying it more attention, the 1st couple i didn't raise an eye brow just one of them things.....

One was 1960/70's stuff, the others much more modern.

[Noddy]

There are often clues left behind after even complete burn outs inside consumer units.

Faults on the neutral bar are not unknown but most fires I attend are down to resistance faults at connections.

Because copper creeps what are thought to be tight connections can come loose which is why boards have stickers for the sparky to remove after they re-tighten the terminals. 

The increase I think is down to the number of things we plug in these days increasing the draw on the installed circuits. 

[Matt]

Lots of new electrical items draw less power then the older versions of things so in theory the electrical current drawn should be probably around the same it always has if that makes sense (more things plugged in but less drawn per device).

Be interesting to see some figures on fires involving consumer units, think the issue could be bigger than I first though.

[Noddy]

I'm not so sure Matt. I understand the electronics stuff has little draw but there is certainly an increase in white goods usage, other kitchen appliances and mod cons.  I also doubt many of us unplug chargers for phones etc.. when we aren't using them.

The issue is a big one.  As is the increase of fires we've seen at the service head / main fuse away from the consumer unit.

Going back to consumer units, there must be something that made it necessary that all new consumer units must be metal and not plastic ?

 

[Messyshaw]

The LFB did some work on this a while ago after noticing a peak of such fires

A change in a British standard or wiring regs allowed the use of combustible componants in consumer units that previously had to be fire resisting.

The result was due to the LFB research, the BS was changed and only FR materials can be used again. 

This applies to domestic consumer units only.

I am working away from home for a few days but will see what I have on this subject when I get home.

[Keith]

Noddy was a bit surprised by the comment that all consumer units must be metal and not plastic, so done a bit of searching round and more accurately they must be non combustible.

As Messy has said there was a change that allowed the use of combustible components to creep in but the regulations have been tightened up again to prevent it again. Reading some of the stuff on a few electrical forums and the general feeling seemed to be that as usual it seemed to be down to cost. Instead of quality metals and FR materials cheaper items crept in to get the price down, so there is probably a lot of them out there. If you're installing a "quality" product it can still be insulated and meet the new specifications.

On the service head / main fuse could it be the case that some of these are down to "interference" to bypass the meter?

[Dyson]

The most recent one i had was 3 phase, into a shop. The others were all domestic, one at an HMO though. 

All plastic, and combustable materials.

My station attended one recently that resulted in loss of life, can't say any more now as the inquest has not been heard.

[StephenKP]

This link might be of interest, talks about the 2016 revision to the IEE regulations seventeenth edition headline facts quoted as "421.1.201 Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and shall:

(i) have their enclosure manufactured from non-combustible material, or

(ii) be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12."

[Noddy]

10/10 Keith that's what I meant

The service head/main fuse issues I have seen are purely down to age where oxidation etc... leads to increased resistance.  Thermal runaway can then occur if the loads are at peak.

And yes, of course if people tamper with it for horticultural reasons then this can result in excessive loads. 

[Keith]

Was watching The One Show last night and it featured an item on Smart meters, which turn out not to be that smart, but the thing that actually caught my eye was the state of the wiring in some of the properties, truly shocking. (sorry about the pun) Sort of confirms what I said earlier in the thread, that I'm surprised that we don't attend more fires involving meters and consumer units.