10mm cable getting stuck in ducting?

[Pete]

Having a problem pulling 10mm cable (supply for hob in island unit) through 20mm ducting. The cable keeps on getting jammed and I wondered if it will be ok to pull it through from the consumer unit end with the outer sheath stripped off? The 20mm duct was put in before the concrete slab, which is Passive so it is within the EPS. The duct is directly under the unit where the hob isolation is situated and I can continue the 20mm duct to the entrance to the back box. Hope the answer is yes!!

[Jeremy Harris]

First question:  "Does the hob actually need 10mm²?"

 

20mm conduit is damned tight, even for 6mm² (our island fitted hob is fed with 6mm², but the under slab conduit is 25mm).  6mm² T&E in a buried duct is OK for up to 41 A, which equates to a hob rated at about 9.43 kW.  If the conduit is running deep in the EPS then I'd be inclined to treat it as being within insulation and derate 6mm² to 34 A, still OK for up to about 7.82 kW.

 

If you wish to run 10mm² single conductors down the conduit then that's fine, but you will need to use conduit at either end to provide the second insulation layer required.  Could be a bit of a faff to run conduit into back boxes etc, but probably doable with some flex conduit sections.

 

My choice would be to look to see if you can get away with running 6mm² and then using a bit of cable lube (after attaching the pull-through) to ease it through the conduit.  This stuff is safe to use with PVC insulated cable: https://www.cef.co.uk/catalogue/products/1748927-aqua-gel-ii-cable-pulling-lubricant

[Conor]

Nope.

 

Try it again with a little fairy liquid  on the leading end, works wonders.

[nod]

I’d the same problem 12 months ago Post titled Cock Up

I couldn’t get 10 mill through and ended up doing as Jeremy says Hob works a treat 

[ProDave]

If the cable goes part way, then first feed something smaller as a draw string through. then try again with the end attached to the drawstring with one person gently pulling on the drawstring and another person feeding it in to the conduit making absolutely certain the cable enters flat with no twists or kinks.

 

A bit of lubricant may help

 

But this is why I used 25mm conduit for out island.

[Temp]

If not already tried get someone push the cable in while you pull.

[PeterW]

Flat box strapping works well as a draw wire and can be quite easy to pull and push through. Duct taping the cable to it in a few places tends to make it easier. 

[Barney12]

18 hours ago, Conor said:

Nope.

 

Try it again with a little fairy liquid  on the leading end, works wonders.

 

 +1 It’s got me out of trouble before.

[Alexphd1]

Deleted 

 

Edited September 6, 2019 by Alexphd1

[joe90]

Years ago the DNO tried to pull cable into my place through their duct and asked if I had any talcum powder to help them, it worked well.

[Pete]

2 hours ago, joe90 said:

Years ago the DNO tried to pull cable into my place through their duct and asked if I had any talcum powder to help them, it worked well.

Talc also works for bald/shaven heads. If I have a sweaty head and I ask SWMBO to run the trimmers over it she puts talc on it and it stops the judder.