Cable entry to 'non combustible' consumer units

[Graham.]

" Wallace was getting lonely without a friend so I bought these and now he?s happy and has someone to eat Wensleydale with again. Pack size is too big for a diyer "

[Chris Green]

Moving further on in my consumer unit replacement exercise I have just been looking at my 18th Edition 'On-Site Guide' and it says in section

2.2.6:-

(c) The cable installation entry method shall, so far as reasonably practical, maintain the fire containment of the enclosure. It is essential that account be taken of the manufacturer's instructions, if any.

This can generally be achieved by the installer ensuring that cable access holes in the enclosure do not leave gaps greater than:-

• 1.0mm for the horizontal top surface and * 2.5mm for all other surfaces of the enclosure that are accessible after installation

.....

How can one possibly manage this with flat T&E cable? Do new CUs come with oval cut-outs sized for T&E - it seems rather unlikely. Would any trunking used to cover cables as they enter the CU also have to be 'non-combustible'?

I'm aiming to mount the CU fairly high up, about 75 to 100mm from the ceiling. Nearly all the cables will be coming down from above, through the plasterboard ceiling. Would it satisfy the regulations to encase the whole space between the CU and the ceiling in metal?

[Roger Hayter]

I believe the answer is intumescent goo - fortunately I have no personal experience.

[spuorgelgoog]

Squishy grommets

Unfortunately these nice cheap ones

"are not 3rd amendment grommets"

There are also glands suitable for flat cables eg

Owain

[spuorgelgoog]

" It's rubber, it's pliable, it fits well, what more can I say. "

I wonder what some people are using them for, I've never felt the need to soften them in warm water before using.

Owain

[Tricky Dicky]

Here is what I am doing on the CU in the garage

All I have used is conduit couplers and brass bushes to hold them in place once the wiring is finished I will be squirting in intumescent sealant to restore integrity (as recommended by Adam).The only slight problem is that the 20mm couplers are shorter than the 25mm coupler so needed a couple locknuts under each to bring them level. Fortunately MK give precise dimensions for the knockouts on their data sheet so I was able to make a drilling template for accurate drilling into the trunking.

Richard