Cables in conduit?

[Chunky]

I am on a job at the moment and we are pulling 12 4mm's down 25mm conduit?This can't be right.It is so tight.What should be the limit?

 

[Guest123]

I would say the conduit space fator is by far exceeded, I'm amazed you can physically get them in there!!

There are calcs you can do to confirm, you'll find the factors in BS 7671 or the OSG.

 

[Spudnik]

I know of a sparky who likes to try and get 2.5 T&E through 20mm conduit.

 

[solo2771]

i believe it is 45% volume or is that the whisky

 

[Sintra]

Have a look here it also gives some examples and how to work out the capacity.

 

[La Poste]

I'm allways a little confused by this 45% rule.
How does it explain capping or tubing running in walls supplyling ring mains, they are filled to well over 45%.
And oval running from light switches up the walls to the lights, they are filled easily more than 45%.
What about the conduit supplying the fuse board? That's usually full to bursting.
But the most common one I see is oval running from the light switch up the wall behind the plaster filled with lighting cables.
Who really obeys this 45% rule?

 

[Adam W]

Not the most reliable source but one of my college tutors reckoned it was physically impossible to get enough cables in a conduit to exceed the maximum capacity.
With capping or oval conduit one side of each of the cables is likely to be in contact with the plaster, which I would have thought would dissipate some of the heat.

 

[Mark_Burgess]

I am on a job at the moment and we are pulling 12 4mm's down 25mm conduit?This can't be right.It is so tight.What should be the limit?

Serious amount of cable lube required there!!

 

[telectrix]

was on a subbing job once in a hospital. 6 x 4mm low smokes down 20mm tube. had to get 1lb of lard from hospital kitchen

 

[cornburn]

I know of a sparky who likes to try and get 2.5 T&E through 20mm conduit.

That's ok isn't it? You can get 3 through if you really need to!

 

[nickblake]

I use conduit for twin and earth especially in garages where protection is required

 

[cef]

I know of a sparky who likes to try and get 2.5 T&E through 20mm conduit.

Even two or three of them!