After some conduit advice, please :-)

[PotatoSoup]

Hi there, thank you for reading this.

I tried to get my head around conduit sizes but my brain melted trying to get to grips with the maths involved - I'm still twitching...

Please can someone more numerate than I am tell me what size diameter conduit I would need to run 5 x 4mm2 t&e cables, 1 X 6mm2 t&e cable, 2 X 1.5mm2 t&e cable and 1 X 2.5mm2 t&e cable through it? Is it possible to even run that many cables through one conduit?

It's to pass the cables from the wall above the consumer unit, across the (under the stairs) ceiling, which is 87cms wide, through the wall and into the living room. I'm going to stuff the ceiling full with acoustic insulation so want my electrician to have an easier time of it if I ask him to add in extra circuits in the future. I also want to add some sort of intumescent seal or seals at either end so if a fire starts in the cupboard it won't be able to travel to the living room or get to the stairs through the holes made for the cables but I have to source the conduit first. I'd really appreciate any help with this. Thanks so much in advance!

 

[Taylortwocities]

Conduit is normally used for single insulated conductors. Basically you just want to box them in.
Have a look at maxi trunking here https://www.tlc-direct.co.uk/Main_Index/Trunking_Pvc_Index/index.html

Note: Stuffing a lot of T&E cables close together may invoke a grouping factor which could reduce the maximum current carry incapacity of some of the cables.

 

[PotatoSoup]

Thank you, Taylortwocities, I really appreciate your advice.

The trunking comes in the following sizes:
50 x 50
75 x 50
75 x 75
100 x 50
100 x 100

Please could someone tell me, would I need two lots of trunking to fit all those cables in or will one of those do it? And what size of trunking should I use? I'd like my electrician to rock up and feel happy to do the job - not like he wants to down tools and skip off into the sunset or give me a slap round the back of the head!!

 

[Taylortwocities]

Let your electrician make the choice. There are regulations regarding percentage occupancy in trunking. You can’t stuff them all in the smallest one.

PS I assume he is running all these new circuits?

 

[PotatoSoup]

He will if I add new circuits down the line, yes. But at the moment, I just want to run the cables for my current circuits through the trunking so I can insulate around them. I also want to make the cupboard fire safe and various other things, but I can't do that until I have any trunking in place. So is there not a way to work out the size of trunking needed without knowing the ins and outs of each circuit involved? I suppose I could call him and ask but are you saying he'd need to come over and do a load of calculations to work it out? If so, I'd better get a load of chocolate biscuits in!!