Plastic compression glands for T&E into metal CU

[Pat H]

I'm sure this will have come up but what are the thoughts on cable entry into metal CUs?
Obviously from the rear is simplest but if cables have to come in from below then do we need to use metal glands or are plastic ok?
I assume for RFC its best for both legs of the circuit to enter together (although I think in terms of eddy currents as long as the L & N in the T&E are together that's all that's needed)

Been talk of ensuring the fixings to the wall are fire proof but even if use plastic raw plugs the screws are metal and I can't see a box falling off if it got really hot.
Also thinking some Intumescent sealant around the back to help seal the rear entry cables will effectively glue it in place anyway!

(Hey spelt topic right this time

 

[sparksburnout]

These ideas for metal cu's are fine in new installs but there are countless thousands of existing installs where like for like simply isn't feasible................. so you have to apply a large dose of common sense.

Steady on.

 

[sparksburnout]

I'm sure this will have come up but what are the thoughts on cable entry into metal CUs?
Obviously from the rear is simplest but if cables have to come in from below then do we need to use metal glands or are plastic ok?
I assume for RFC its best for both legs of the circuit to enter together (although I think in terms of eddy currents as long as the L & N in the T&E are together that's all that's needed)

Been talk of ensuring the fixings to the wall are fire proof but even if use plastic raw plugs the screws are metal and I can't see a box falling off if it got really hot.
Also thinking some Intumescent sealant around the back to help seal the rear entry cables will effectively glue it in place anyway!

(Hey spelt topic right this time

Are you serious?? fire proof fixings to the wall???? What sort of state do you think the house will be in by the time the CU has fallen off the wall and posed a danger to anything or anyone FFS?????????? Did someone mention common sense somewhere?

 

[HandySparks]

Let me know if you find some metal rawl plugs

http://i.stack.Upload the image directly to the thread.com/ou9oP.jpg

 

[Pat H]

Common sense is fine but it can't override the regulations.
Of course if the regulations were written in plain sensible English that would be fine.
But they aren't they are an evolved set of statements that leave many areas open to some interpretation.
So its helpful to try and understand the intent of the regulation changes.
I'd expect the need for a metal CU to be to contain a localised fire caused by overheating. Plenty of vids online of burning CUs.
So it makes sense to ensure a small fire in a CU is contained. If the CU has a small fire and gets very hot then its important that the box stays put. If it should break loose then it could open rear cable access holes and allow the fire to not be contained.

So in my view if you are going to the trouble of following a reg to use a metal enclosure to help reduce the risk of fire you may as well do it right.

If its a plasterboard wall then there are plenty of metal fixing options:
CAVITY PLASTERBOARD DRYWALL PLUGS SCREWS SPRING TOGGLE SPEED PLUGS METAL PLASTIC - http://www.ebay.co.uk/itm/CAVITY-PLASTERBOARD-DRYWALL-PLUGS-SCREWS-SPRING-TOGGLE-SPEED-PLUGS-METAL-PLASTIC-/201597296886?var=500815220936&hash=item2ef022a0f6:m:mUhTovlsxjG6D0nAkYXhs1A

 

[Nickj]

Wall dogs (good masonry screws) do the job very well and are a faster install than using any type of fixing.

There are reports that show the plastic wall plugs melting and the consumer unit falling from the wall well before the house is destroyed.

 

[Leesparkykent]

Or use Dewalt wall dogs and you don't need plugs.

 

[sparksburnout]

Wall dogs (good masonry screws) do the job very well and are a faster install than using any type of fixing.

There are reports that show the plastic wall plugs melting and the consumer unit falling from the wall well before the house is destroyed.

Are there?? Have you got a link to one??? What a load of rubbish. As has already been said the heat sinking properties of a masonry wall into which a plastic plug has been fixed will keep it in place for well beyond the effects of smoke inhalation and spread of fire will have rendered life in such a building over.

 

[Nickj]

There is one in another thread. I'll take a look for you and try to remember to post tomorrow

 

[Pat H]

It all comes back to the responsibility of the installer should anything happen.
If in the future there was a fire and it was considered the CU had come away what then of the installer?
If you have installed in way that helped prevent that then not only are you covered but possibly you've help limit a danger.
Seems to me a simple step for little extra cost or time for maybe a very small additional bit of protection.

 

[sparksburnout]

It all comes back to the responsibility of the installer should anything happen.
If in the future there was a fire and it was considered the CU had come away what then of the installer?
If you have installed in way that helped prevent that then not only are you covered but possibly you've help limit a danger.
Seems to me a simple step for little extra cost or time for maybe a very small additional bit of protection.

I'm sorry but I think this is just absolute nonsense. I do not accept that such a fixing would fail unless the building involved was an absolute blazing inferno. If you are seriously worried about this then I have no idea how you ever get to sleep at night?

 

[Pat H]

I don't worry about it. Its an easy thing to not worry about. Just fix with a non plastic fitting.

 

[sparksburnout]

I don't worry about it. Its an easy thing to not worry about. Just fix with a non plastic fitting.

OK, well done, Carry on...

 

[Leesparkykent]

Fire performance of cable supports - IET Electrical - http://electrical.------.org/wiring-matters/58/bre-report/index.cfm

@Nickj here's the document you referred to and its fire 2 results that links the collapse to the wall plugs melting after approximately 20 minutes.

I agree with @Pat H that for the added little expense and no real extra time actually carrying out the work than the conventional method warrants it if you don't mind going above and beyond what's required.

 

[sparksburnout]

Fire performance of cable supports - IET Electrical - http://electrical.------.org/wiring-matters/58/bre-report/index.cfm

@Nickj here's the document you referred to and its fire 2 results that links the collapse to the wall plugs melting after approximately 20 minutes.

I agree with @Pat H that for the added little expense and no real extra time actually carrying out the work than the conventional method warrants it if you don't mind going above and beyond what's required.

Oh for goodness sake this is ridiculous. The document is referring to cable systems in mostly non-domestic situations where fire fighters have been trapped by cables collapsing into fire escape routes, not domestic CU's falling off the wall!!

 

[westward10]

What is it about a straightforward task like fitting a metal CU that causes soo.. many problems, is it just me.