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Topic Title: Underground duct fill capacity
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Created On: 12 August 2014 02:19 PM
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 12 August 2014 02:19 PM
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Posts: 3
Joined: 10 June 2004

Ok tired of looking in the regs.
What is the maximum amount of cable fill in an underground duct network.
I've also looked on the internet and there are different fill capacities, some say 40% and others 45%.
I understand the tables and factors for trunking and conduit but there is nothing for in-ground duct runs.

When at college we were told there should only be 45% fill (rule of thumb).

Anyone got any ideas
 12 August 2014 02:52 PM
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Posts: 7856
Joined: 18 April 2006

I'd work backwards, how full can you get a duct?

How many 40 mm diameter cables can you get in a 125 mm duct and what % does this work out to be?

Next work out the rating factor for the number of circuits you have in there.

Lastly, how much lubricant have you got?



When I was a kid people used to cover me in chocolate and cream and put a cherry on my head. Yeah, life was tough in the gateau.

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