Fire Retardant Grommets

[Taylortwocities]

The intent of Regulation 421.1.201 is considered to be, as far as is reasonably practicable, to contain any fire within the enclosure or cabinet and to minimise the escape of flames. Like so much else, it depends on your interpretation of the word "reasonably".

 

[Grant1987]

The intent of Regulation 421.1.201 is considered to be, as far as is reasonably practicable, to contain any fire within the enclosure or cabinet and to minimise the escape of flames. Like so much else, it depends on your interpretation of the word "reasonably".

I agree, just speaking from experience the inspector didn’t like open or blind grommets, I did though until then lol

 

[Dartlec]

421.1.201 that’s the one
[automerge]1598139945[/automerge]

I’ll be honest here, reason why I know this is because I got picked up on it by inspector A year ago when I used open grommets on consumer up tight to ceiling without proper fire sealing it and making sure it’s an enclosed chamber to prevent the escape of fire. He recommended the flame retardant grommets

As usual, The regs manage to make things more complicated by not being clear about their requirements and leaving it to people to find a way that most people thing complies.

I'd have thought open grommets wouldn't meet the IP rating for the top surface of a consumer unit in any case?

But all reg 421.1.201 really says is that consumer units should be manufactured from non-combustible material. It says nothing about any subsequent holes that you create in the thing during installation (it probably should imo). When using rear entry holes then there is not even an available flame retardant option that I'm aware of? Partly because they are not standard.

I've seen several of the Youtubers talk of filling the rear gaps with flame retardant sealant, but that doesn't seem to be a regulation, just an idea of 'good practise' that has grown up while people try to interpret what a reg means.

And since for CUs the only suitable example of non-combustible given is ferrous metal then if the reg applied to connections they'd also have to say that all grommets should be metal to be consistent, which isn't exactly going to work.

A lot of the meter tail glands now recommended are plastic anyway, and likely not flame retardant (Wiska do make one similar to their FR grommets having said that)

Personally I use the FR grommets because they are easy to force cables through (including post installation) and seal fairly well afterwards and although more expensive than blind grommets the cost is small compared to a consumer unit on a job.

 

[davesparks]

I agree, just speaking from experience the inspector didn’t like open or blind grommets, I did though until then lol

Inspector of what? The building inspector?
[automerge]1598141883[/automerge]

421.1.201 that’s the one

That regulation says non-combustible, flame retardent is not non-combustible, these are different things.

 

[Grant1987]

Inspector of what? The building inspector?
[automerge]1598141883[/automerge]


That regulation says non-combustible, flame retardent is not non-combustible, these are different things.

Inspector from Council I done work for, it also states that cable entry points should be adequately sealed it’s a grey area but one which I unfortunately got made a mug out of. He had a couple of pages printed out in front of me and the main boss I can try and find them now and send the link IET I think it was from
[automerge]1598142923[/automerge]

Inspector from Council I done work for, it also states that cable entry points should be adequately sealed it’s a grey area but one which I unfortunately got made a mug out of. He had a couple of pages printed out in front of me and the main boss I can try and find them now and send the link IET I think it was from

 

[Dustydazzler]

Rather than grommets what about thsee ...

https://www.NoLinkingToThis/p/fireproof-gland-kit-red-20mm-10-pack/23277

 

[James]

Rather than grommets what about thsee ...

https://www.NoLinkingToThis/p/fireproof-gland-kit-red-20mm-10-pack/23277

I consider that to be false advertising.

Polyamide (nylon as it is often know as) is not fire proof.
It can be made self extinguishing with the right addatives

Just take a blow torch to one and see just how “fireproof” it really is.

 

[Ian1981]

From Hager’s manufacturers instructions
Read the cable entry part
Extract below

For rear cable access, the minimum number of knockout(s) shall be removed and a cable protector fitted; see illustration above.
Tests on hager consumer units have indicated that there is no specific need for external fire rated cable glands or intumescent sealing in addition to the guidance below, with respect to achieving a non-combustible enclosure. However this does not preclude the designer/installer from using fire rated cable glands or external intumescent sealing should they consider necessary. Internal intumescent pads shall not be used.

Also

cable access into the metal consumer unit must maintain the integrity of the non-combustable consumer unit so far as reasonably practicable. This can generally be achieved by the installer ensuring that cable access holes they make in the enclosure do not to leave gaps greater than:
· 1.0 mm for the horizontal top surface and
· 2.5 mm for all other surfaces of the enclosure that are accessible after installation.

So in conclusion, flame retardant or whatever you want to call it , grommets are not required but are not precluded, an inspector cannot fail or say it is unsatisfactory if you have not used them and quoting regulation 421.1.201 is pointless as that regulation does not specify such things.
A metal consumer unit is not a fire barrier, I mean for god sake there’s combustible mcb’s and devices installed In it.

 

[Dustydazzler]

Ok , what about these ?

20mm T.R.S. Stuffing Glands

20mm T.R.S. stuffing glands available for some of the best prices online with fast, free delivery on orders over £100 excluding VAT. Please call 01244 288138 for further information.

quickbit.co.uk

 

[GBDamo]

From Hager’s manufacturers instructions
Read the cable entry part
Extract below

For rear cable access, the minimum number of knockout(s) shall be removed and a cable protector fitted; see illustration above.
Tests on hager consumer units have indicated that there is no specific need for external fire rated cable glands or intumescent sealing in addition to the guidance below, with respect to achieving a non-combustible enclosure. However this does not preclude the designer/installer from using fire rated cable glands or external intumescent sealing should they consider necessary. Internal intumescent pads shall not be used.
View attachment 60338
Also

cable access into the metal consumer unit must maintain the integrity of the non-combustable consumer unit so far as reasonably practicable. This can generally be achieved by the installer ensuring that cable access holes they make in the enclosure do not to leave gaps greater than:
· 1.0 mm for the horizontal top surface and
· 2.5 mm for all other surfaces of the enclosure that are accessible after installation.

So in conclusion, flame retardant or whatever you want to call it , grommets are not required but are not precluded, an inspector cannot fail or say it is unsatisfactory if you have not used them and quoting regulation 421.1.201 is pointless as that regulation does not specify such things.
A metal consumer unit is not a fire barrier, I mean for god sake there’s combustible mcb’s and devices installed In it.

Agree whole heartedly.

However BS7671is not always our only requirement to follow.

Often with big companies/councils there are adopted working practices which are the result of personal preference, which is fine if agreed to in advance.

Whats annoying is where you are not made aware of these foibles, don't do them and they try to make out its "best practice" or "in the regs".

 

[Dustydazzler]

Agree whole heartedly.

However BS7671is not always our only requirement to follow.

Often with big companies/councils there are adopted working practices which are the result of personal preference, which is fine if agreed to in advance.

Whats annoying is where you are not made aware of these foibles, don't do them and they try to make out its "best practice" or "in the regs".

BS7671 is only guidance , so if pish came to shove saying it’s a regulation to use metal glands over plastic isn’t technically accurate...

 

[davesparks]

Inspector from Council I done work for, it also states that cable entry points should be adequately sealed it’s a grey area but one which I unfortunately got made a mug out of. He had a couple of pages printed out in front of me and the main boss I can try and find them now and send the link IET I think it was from
[automerge]1598142923[/automerge]

View attachment 60337

In which case it sounds like it might be the councils specification and not a part of BS7671.

 

[westward10]

Inspector from Council I done work for, it also states that cable entry points should be adequately sealed it’s a grey area but one which I unfortunately got made a mug out of. He had a couple of pages printed out in front of me and the main boss I can try and find them now and send the link IET I think it was from
[automerge]1598142923[/automerge]

View attachment 60337

At no point in the Regulation quoted does it state any of that. The intention is not to contain any fire, if it were then the enclosure would have to be constructed for this purpose but it is not.

 

[Midwest]

You could always follow Wylex gimmick, and install intumescent pads inside your CU.

 

[nicebutdim]

You could always follow Wylex gimmick, and install intumescent pads inside your CU.

View attachment 60351

Even the wholesalers didn't fall for those. They're available from basically nowhere.

 

[David Prosser]

Your meant to be using these flame retardant grommets rather than open grommets to comply with regs.

no I’m not.

 

[nicebutdim]

Am I right in stating that the requirement to leave gaps no greater than 1mm in the top horizontal surface of CUs would generally preclude the use of open grommets, but that nowhere in BS7671 is there any stated requirement for those gaps to be filled or reduced through the use of any flame/fire resistant/retardant material?

 

[davesparks]

Am I right in stating that the requirement to leave gaps no greater than 1mm in the top horizontal surface of CUs would generally preclude the use of open grommets, but that nowhere in BS7671 is there any stated requirement for those gaps to be filled or reduced through the use of any flame/fire resistant/retardant material?

The requirement is to maintain the specified IP rating, which is different to just not leaving gaps greater than 1mm.

But otherwise yes, that pretty much the gist of it.

 

[Grant1987]

The requirement is to maintain the specified IP rating, which is different to just not leaving gaps greater than 1mm.

But otherwise yes, that pretty much the gist of it.

I wish I had known all this a year ago I was like a rabbit in the headlights but good to know the exact requirements now ?