Fire sealant for back of distribution board?

[LewisM]

Anybody recommend a good intumescent sealant that can be applied directly to PVC cables?

 

[DPG]

Did you have a straight face when you typed that last line Andy?

 

[Pretty Mouth]

Here's a couple of articles that are relevant to this thread, both from the IET wiring matters back in 2015. It will come as no surprise to learn that they give conflicting advice.

This one appears to say you need to (Sealing on wiring entries):

https://electrical.------.org/wirin...ble-enclosure-requirement-for-consumer-units/

...while this one appears to say you don't (last FAQ):

https://electrical.------.org/wirin...-winter-2015/consumer-units-a-brief-overview/

 

[Mike Johnson]

I think we are all singing from the same hymn book, I would agree that if it's only the DB that has been opened at the back then it should not need any additional fire protection, but if the wall behind the DB has been penetrated then it may need fire stopping if that wall was a fire barrier to the next room or to the ceiling or roof above, well that's my take on it.

 

[westward10]

Cavity walls should have internal cavity barriers in place to prevent the spread of smoke and fire. You should consider cavities as individual cells and at no point should a cavity barrier be breached without fire stopping. The only time a cavity wall needs sealing is where both sides are breached which would allow spread from one compartment to another. Using one side as a cable route will not necessarily breach its protection due to the internal cavity barriers and on this basis no additional fire sealing is required.

 

[Mike Johnson]

If I remember correctly the regulations say horizontally at floors and vertically at party walls, the interpretation of that leaves a lot to be desired, you only officially get party walls on terraced house's, so unless the cavity is fire stopped in a detached house you could get a spread of fire or smoke from room too room if the internal skin had been penetrated and not fire stopped, just a thought.

 

[westward10]

Cavity walls if correctly constructed should not allow spread between compartments.

 

[Ian1981]

If the cables came through a pink 15mm fire board then yes maybe the hole around the cables should incorporate a fire barrier but not the rear entry of the enclosure.

 

[Dustydazzler]

If the cables came through a pink 15mm fire board then yes maybe the hole around the cables should incorporate a fire barrier but not the rear entry of the enclosure.

yes i Think the plaster board should be repaired if it’s been hacked.
but the actual consumer unit doesn’t require mastic

 

[Ian1981]

yes i Think the plaster board should be repaired if it’s been hacked.
but the actual consumer unit doesn’t require mastic

Agree, I would not fire seal the board.

 

[LewisM]

Existing DB has metal trunking and rear entry on a wall which is a fire barrier. Only rear will be sealed not trunking.

 

[davesparks]

I'll chuck 527.2.1 into the mix.
Where a wiring system penetrates any building element that has a prescribed fire rating it should be sealed back to that rating.

Not to do with sealing a CU, but maybe the wall behind it if it needs to be. Rear entry penetrations I'm on about.

Indeed it does, and it essential that penetrations to anything with a prescribed fire rating are properly sealed.
As far as I know there are very few parts of a domestic construction which have a prescribed fire rating. RSJs have to be protected by fire resistant (pink) plasterboard normally, but that's about all I can think of.

Obviously normal plasterboard is used in the construction, which does have a fire rating, but that doesn't mean that everywhere it is used has a prescribed fire resistance.

 

[Mike Johnson]

All plasterboard has a fire resistance of 30mins no matter what colour is, some times a double layer of standard white plasterboard is used to achieve the required rating, so the colour is not a good indiction of what the requirement is or that it is a fire barrier.

 

[Ian1981]

All plasterboard has a fire resistance of 30mins no matter what colour is, some times a double layer of standard white plasterboard is used to achieve the required rating, so the colour is not a good indiction of what the requirement is or that it is a fire barrier.

A dwelling is usually a single fire compartment, if however pink board is used say in the attached garage with a bedroom above, that would indicate a separate fire compartment especially if there’s a fire door involved somewhere, so penetration of that compartment would need fire sealing.

 

[Midwest]

I tend to disagree. Whilst a domestic property is usually classed as one fire department, try building a house without covering structural timbers and joist etc with plasterboard and expect to have it passed by your LBC.

 

[Ian1981]

I tend to disagree. Whilst a domestic property is usually classed as one fire department, try building a house without covering structural timbers and joist etc with plasterboard and expect to have it passed by your LBC.

The plasterboard is fixed to the I joists to form the ceiling , that’s it, lam beams etc do not get covered in plasterboard