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boltonsparky

Fire sealing a consumer unit.

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boltonsparky

Don't do many consumer units and since amendment 3 the ones I have done I've done top entry with trunking and the fireproof stuffing glands so the consumer unit would contain the fire.

 

Curious to know what others do on rear entry CUs. Seems pointless to fit a metal clad if it's got holes in the back that are open into a wall or a floor above because that's where the fire is going to go.

 

I know of one manufacturer who makes bespoke CUs that offers a rear entry panel with intumescent sheet that seals the cables as they enter the rear of the CU. 

 

I've also found a manufacturer that makes decent sized intumescent strip that may work for reasonable money but when they charge £16+vat to deliver a £5 item it's a bit pricey to buy just to have a look at. 

 

I've seen people using fire mastic and although in theory this works it just looks cowboy even though it's hidden inside the CU.

 

No point asking the wholesalers round here, most of them look at you blankly when you mention a type A RCD.

 

Interested to know what, if anything, you use.

Edited by boltonsparky

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Andy™

no need to fire seal it - regs say the enclosure is to be made from non flammable but it doesnt say the enclosure must be fire sealed

if you wanted you could stuff some fire pillows in the wall

 

https://www.firesealsdirect.co.uk/passive-fire-protection/fire-pillows-and-barriers/

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boltonsparky

Even though the regs say there's no need to fire seal it it seems daft not to as I thought the whole point of amendment 3 metal consumer units was to stop the spread of a fire from the consumer unit. If anything, leaving it unsealed at the back would be chimneying the fire to exactly where you don't really want it to be going. That's not a dig at you by the way, it's at the stupidity of bringing in a reg that only in part achieves what was intended, not that that would be the first time.

 

Thanks for the link, I'll take a look at them.

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Murdoch

There is no requirement for fir sealing rear entry fuseboards BUT you should take into account the material that is directly behind the fuseboard IMHO

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phil d

This made me laugh, I remember some years ago when they started producing fireproof boards, I was at an elex and a manufacturer was showing me a board it had glands for the holes in the top of the board but nothing for the large knockout in the rear. When I asked about sealing this I was told it wasn't needed, I then asked why and was told, 'well the fire won't come out of the back'. I said that I accepted that if the board was mounted on a brick wall then ok, but what it if it was mounted on a stud wall? He still insisted that the fire would not escape through the large hole in the back, I laughed at that point and replied that most of the places I worked at didn't have well behaved intelligent fires that did as they were told. lol

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SPECIAL LOCATION

If it was an essential requirement manufactures would include such seals and charge even more for a CU ...

 

Seams daft sealing up every nook & crevice just to make it a real sod if you ever have to go back and add a new circuit into the box!!

Also when the blanks to cover any unused MCB slots are just a bit of clip-in plastic!!

 

Forgotten how many Metal CU's have been used during annual inspections.. ?

and so far the topic of fire sealing a CU has never arisen..

 

I did ask once if you should be fitting metal blanks to fill in the spare MCB positions..  and told no need..

 

So why fire seal the back..

But not the front where all your protective devices poke their nose out?

 

:C

Edited by SPECIAL LOCATION

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binky

I have to agree  it does seem silly to leave large holes in a board , but then the PVC cable insulation is flammable and would render any sealing redundant should a fire of sufficient strength occur within a board. Personally I thik this just shows how silly meatal boards are in the first place.

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boltonsparky

Interesting input from everyone, cheers.

 

I've seen a few remnants of consumer units after fires online and one in the flesh and the breakers seem to fair quite well and not act as a fuel, they melt a bit rather than burn whereas the plastic housings are non existent so must burn well. Being metal removes a large amount of the fuel. Taking that into account other than the cable insulation I suppose there isn't a large amount to burn so spread from the consumer unit is less likely and why fire sealing the backs isn't worried about too much. 

 

Obviously prevention is better than cure so proper terminations are key, surprising how many tails I come across that are loose in the main switch.

 

3 hours ago, SPECIAL LOCATION said:

 

But not the front where all your protective devices poke their nose out?

 

:C

 

All the metal ones I've come across have had the metal lid over the MCBs that annoyingly won't stay open, is this part of a British standard to help fire proof the front, unless being held open the lid will be closed covering the front?

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SPECIAL LOCATION
56 minutes ago, boltonsparky said:

All the metal ones I've come across have had the metal lid over the MCBs that annoyingly won't stay open, is this part of a British standard to help fire proof the front, unless being held open the lid will be closed covering the front?

 

Don't think there is actually a specific standard for the way the front hinge...

 

As BG have a mix of both up and down hinged front covers...

As do Schneider..

 

e.g.

https://www.screwfix.com/c/electrical-lighting/domestic-consumer-units/cat7230028#category=cat7230028&page_size=100

 

Although the down-hinged ones to have some sort of latching device..

 

But it is not impossible to leave the front cover hinged down if you so wished..

So it hardly guarantees the cover will be in place all of the time!  

 

:C

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boltonsparky
16 hours ago, SPECIAL LOCATION said:

 

Don't think there is actually a specific standard for the way the front hinge...

 

As BG have a mix of both up and down hinged front covers...

As do Schneider..

 

e.g.

https://www.screwfix.com/c/electrical-lighting/domestic-consumer-units/cat7230028#category=cat7230028&page_size=100

 

Although the down-hinged ones to have some sort of latching device..

 

But it is not impossible to leave the front cover hinged down if you so wished..

So it hardly guarantees the cover will be in place all of the time!  

 

:C

 

Yeah you're right, I've even worked on a schneider one, had forgotten about that, the whole front on those is a bottom hinged lid with a magnet to keep it closed but like you say nothing to stop it being left open. 

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phil d
On 13/01/2021 at 14:36, SPECIAL LOCATION said:

If it was an essential requirement manufactures would include such seals and charge even more for a CU ...

 

Seams daft sealing up every nook & crevice just to make it a real sod if you ever have to go back and add a new circuit into the box!!

Also when the blanks to cover any unused MCB slots are just a bit of clip-in plastic!!

 

Forgotten how many Metal CU's have been used during annual inspections.. ?

and so far the topic of fire sealing a CU has never arisen..

 

I did ask once if you should be fitting metal blanks to fill in the spare MCB positions..  and told no need..

 

So why fire seal the back..

But not the front where all your protective devices poke their nose out?

 

:C

The thing is, when I spoke to this guy he was trying to make out the there was no way a fire could get out of one of their CU's, there's not a lot to stop it getting out if there's a ruddy great hole in the back is there, it doesn't matter where it gets out, if it can get out from anywhere it could be a problem. I even saw one firm that made a metal box that you could fit over a plastic CU, the damned thing was about £150, you could buy one of those metal power tool boxes for about a tenner and cut the back out with a grinder.

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