Metal all the way, no brainer

[andysparkfree]

Hi all, just thought i'dd share the picture of the live distribution board we came across this afternoon following a callout

not only was this live when we got there (seems that the fire brigade removed the wrong fuse from the ryefield board) but is a shocking example why every old distribution board should be changed to metal asap

 

[SparkyChick]

I know it's simple enough, but it's time and materials consumers are paying for instead of having manufacturers produce equipment that is inherently safe due to protection within it.

 

[spark 68]

Exactly, the manufacturers know fine well how their product will be connected in the real world, they are simply penny pinching by requiring external fusing down that should have been provided for within the product in the first place.
To me they should not be fit for purpose imo. RE: the bathroom fan in the post above^^^

 

[Wilko]

I finished my first 100m of 2mm sleeving not so long ago. I thought of Westward when I picked up the replacement. I've got a couple of hundred metres of 3mm, not sure I'll ever use it now...

I use it in the garden now.

 

[Blissof89]

I much prefer working with a metal DB and I fully agree with the AMD 3 changes.

Its not just about bad workmanship, switchgear can fail and cause a lot of heat.

A plastic unit melts when it gets too hot and all of a sudden the existing fire is fed a load of oxygen and it grows as that was the only thing it was lacking before, eventually becoming too large to extinguish . A metal unit contains the fire, hopefully until the supply OCPD operates and the fire starves itself or the fire is noticed, isolated and extinguished. There is little chance for the fire to grow as although it has plenty of fuel and heat there is a very limited supply of oxygen inside the fireproof enclosure, and that isn't suddenly going to change.

Its just risk management, yes you could (and should) crack down on the manufactures and regulate who is fitting consumer units but that is a mammoth task in itself and does not guarantee anything. Fire rated enclosures greatly reduce the risk in the event of a failure and there is no arguing that.

Now metal enclosures on TT systems is a whole other problem, my only suggestion would be a metal enclosure that is double insulated via a plastic coating of some sort but idk how feasible this is.

 

[Midwest]

When the new reg for metal CU’s came in, Certsure web in air vid, with that Darren Standforth what’s his name, said the idea behind the change was to remove a source of fuel (i.e. the plastic enclosure) from a fire. Then they changed the reasoning to containing a fire.

From that op pic, think the former was better reasoning, if at all.

 

[Pete999]

When the new reg for metal CU’s came in, Certsure web in air vid, with that Darren Standforth what’s his name, said the idea behind the change was to remove a source of fuel (i.e. the plastic enclosure) from a fire. Then they changed the reasoning to containing a fire.

From that op pic, think the former was better reasoning, if at all.

The new reg is for CUs constructed from noncombustible materials, just so happens that metal is noncombustible, or in a noncombustible enclosure.

 

[Blissof89]

I guess a metal enclosure both removes the fuel and the oxygen from the fire equation, but I'm fairly sure the core principles behind a metal enclosure is to remove oxygen. There will always be fuel in the way of plastic casings for breakers and cable insulation.

OP's pic is kind of a moot point as the fire started outside the enclosure

 

[Midwest]

Yeah but the enclosure cover has been consumed by the fire, whereas the cabling & switchgear has to, but to a lessor extent. I recall reading somewhere, switchgear, the MCBs etc, are manufacturered from a different grand of ‘plastic’.

 

[johnduffell]

Cus are not designed to keep a fire in or out. Obviously metal is less meltable than plastic but i don't think that was part of the intention of the change in regs.

 

[Midwest]

I don’t know. Whether it was to contain a fire, remove a source of fuel? Presumably there was a reason to switch from plastic to metal.

 

[Blissof89]

Of course a metal enclosure is suppose to limit the spread of fire, why do you think people call them fire rated? As Midwest said, there is a reason we stopped using plastic.

The intent of regulation 421.1.201 is considered to be, as far as is reasonably practicable, to contain any fire within the enclosure and to minimise flames from escaping, caused mainly as a result of poorly installed connections

 

[andysparkfree]

Thinking about it a bit more, if a fire is so close to a fuse board, i think metal or plastic, i wouldn't want to be touching it.

 

[Midwest]

Dunno if you've watched this vid? Whilst they don't suggest metal CU's are supposed to be fireproof, nor remove source of fuel, and its bit old guidance by now, still interesting vid about metal CU's back then. Sound needs adjusting at beginning.

Fire protection: panel discussion 1 at the ELEX show in Harrogate - https://electrical.------.org/wiring-matters/issues/56/fire-protection-panel-discussion-1-at-the-elex-show-in-harrogate/