Expanding fireproof foam.

[graeme210375]

I have replaced a cu (in readiness for an Elecsa assessment) which is mounted on a stud wall. There is a hole in the wall behind the existing cu where all of the cables enter. As I fitted the new cu in the same location, I left the hole.
I was advised by a Building Control supplied spark that the hole can be filled with expanding fireproof foam and needs to be filled to conform with regs
My question is, does this foam degrade the insulation on the wiring? Or is there a better way of filling the gap?

 

[kevyn]

You can get fire foam that is ok with cables from newey & eyre. Also if the stud wall is not a fire barrier then why fill it?

 

[SYKRAPS]

My question is, does this foam degrade the insulation on the wiring?

Never used it myself but I guess the best people to ask are the manufactuers of the expanding foam, I would be cautious though even if it is ok to use because foams like these often expand more than you would expect and you could find it contaminating your CU if you are not careful.

 

[Elmer BeFuddled]

You can get fire foam that is ok with cables from newey & eyre. Also if the stud wall is not a fire barrier then why fill it?

Any chance of a link/catalogue number? I'm getting nowhere!!

 

[MarkieSparkie]

To comply with the Building Regulations Approved documents B and P you need to fill all small penetrations of the building structure with an intumescent sealant (eg. Siroflex Flameguard range), which expands in the presence of heat @200 degrees C. Technically it's not fire-proof it's fire-resistant. I doubt the system will allow direct links, but Screwfix order code 70510 or Toolstation order code 78013 are both suitable.

Large penetrations should be filled with a B1 Fire Retardant Foam (eg. Siroflex Flameguard range).

If you require a local stockist contact Siroflex:

Siroflex Ltd
Dodworth Business Park,
Dodworth,
Barnsley,
South Yorkshire
S75 3SP
Email: [email protected]
Tel. 01226 771600
Fax. 01226 771601
Siroflex Limited only supplies appointed merchants and distributors, we therefore do not supply or sell directly to the general public. Please contact us for the name of your nearest stockist.

​

http://www.siroflex.co.uk/content/SXrange/cont_TSfire_retardant.html
http://shop.fireguard.co.uk/intumescent-acoustic-mastic-47-c.asp
http://shop.fireguard.co.uk/fire-rated-acoustic-expanding-foam-48-c.asp
http://www.amazon.co.uk/gp/offer-li...ve=22282&creativeASIN=B0046B0QZ8&linkCode=asm
http://www.amazon.co.uk/gp/offer-li...8134524970566766310230400008005&creative=2228

 

[Rockingit]

To the OP - just a word of warning from the wise - Siroflex is great for the job (always got one on the van) but it takes AGES to cure and go hard and makes one heck of a mess if you forget that!

 

[kingeri]

Siroflex is awful to work with and unnecessary in most situations....

 

[HandySparks]

I would not use the expanding foam to seal around cables as it will be a good thermal insulator and significantly reduce the current carrying capacity of the cables. If you need to fill a hole, use plasterboard to fill any big holes and intumescent mastic to complete the job and fill in the small gaps.

 

[graeme210375]

Great responses, many thanks for the help. As there are only 5 circuits, my plan is to remove the cu anyway and make good. I have to extend a some of the conductors in the unit anyway as they are stretched a bit tight, so it will give me a chance to neaten it all up. Thats a whole other debate though crimp vs wago, to extend conductors in the cu.

 

[brman]

fwiw I keep a tub of ready mix plaster in the van. depends on the hole but that generally does the job with minimum fuss......

 

[londonlec]

I must say I had a similar conversation with my NICEIC assessor last year. He said he sees too many jobs with huge holes in the plasterboard.
I am guessing conversion flats where some walls are fire barriers.

 

[graeme210375]

I must say I had a similar conversation with my NICEIC assessor last year. He said he sees too many jobs with huge holes in the plasterboard.
I am guessing conversion flats where some walls are fire barriers.

The property i was working on mainly comprised stud walls. Even all of the load bearing walls were battened and boarded. The chap from Building Control was concerned about any potential fire finding a route through all of the studwork.

 

[Engineer54]

Whatever method you use to seal the hole in the plasterboard stud wall, make sure you protect the cables from any plaster or foam etc. Otherwise it will be nigh on impossible to remove or add cables to or from the CU in the future!!!