Electrical penetrations in 30 minute fire ceiling

[Jdwood38]

Hi all,

Not sure if this should be in electrical or one of the other forums but sure the problem is encountered a lot more here! Have also tried searching and can't find the answer.

Just wondering what the correct method is for protecting cables penetrating a 30 minute fire ceiling? I can see there's loads of collar options online but these are all for much larger penetrations! I only need to do a number of 2.5mm T&E's and a few Cat6s dotted around the perimeter of the room and dropping down in conduit (conduit doesn't penetrate the ceiling, just the cable, conduit stopping a few mm short of the ceiling). This must be a common issue that needs managing, e.g. for mains interconnected smoke detectors - how do developers seal where the cable comes through the ceiling into the detector?!

Thanks in advance for any suggestions.

 

[Scally-Ho]

I would leave that decision to the fully qualified and experienced sparkie tasked with doing the work, but however it is achieved, we have to remember about cable derating factors when passing through or covered by insulation. The wiring regs for electrical installations are a minefield for those who do not understand them.

 

[Jdwood38]

I appreciate the response and do understand, however building regs have changed a lot since I was qualified, and this is a building regs question. There is no sparkie doing the installation because the installation is already there - this is adding a 30min fire rated ceiling around what is already there so there's no EIR etc to be completed unless of course there is no choice but to redo it all. Then a sparkie will do it, but I want to understand what the options are first. This is a DIY forum after all...

I could simplify and make it just about the Cat6s instead?

Thanks all the same...

 

[333rocky333]

All i have seen whether right or wrong , mainly in ceiling voids passing through firewalls out of site is that fire rated mastic type sealer like sold in screwfix round the wires and often done by professional companies with there company sticker next to it stating its sealed so they seem confident

 

[crystal ball]

I was working in a school loft running data, there was a fire barrier right across the loft, also a hole the size of a scone with a fire alarm cable through it

 

[EFLImpudence]

Was it an intumescent scone?

Isn't that all that is needed by the OP?
Whatever is done - as Rocky says - seal with intumescent material.

 

[Gigagator]

Was it an intumescent scone?

Do you put jam or cream on first on your intumescent scones? I'm a cream first kinda guy.

 

[EFLImpudence]

Yes, cream first - the proper way - I'm from Devon.