Wiring through trunking

by **andy2510** » Sun Jul 20, 2008 7:14 pm

Hi guys. I have a question which many of you electricians may have resolved in the past.

How do you get a cable to turn the corner in the trunking in between walls?

I'm trying to run a coax aerial cable from the loft to the living room though the current trunking (which is quite narrow) but I want to leave the current cable in place for FM transmission (using a 4-way booster in the loft). But every time the cable hits the corner it won't budge!!! Access to the trunking is difficult in the first place!

Any help or tips will be greatly appreciated!!!!

by **ericmark** » Mon Jul 21, 2008 1:07 am

I will guess it's not trunking but capping. Capping is used to protect the cable while the wall is plastered and is not intended to allow replacement cables to be drawn through it. Although in many cases one can draw cables through it. Trunking will normally have a removable lid and will normally have back where capping normally has no back to it. Sometimes one can just remove small bits of plaster at the top of a wall to allow access to capping but much depends on bricks or breeze blocks behind the capping and how rough they are.

Eric

by **andy2510** » Mon Jul 21, 2008 5:02 pm

Thanks for your reply.

The capping is like a pipe in the loft space, running horizontally then with a 90 deg turn downwards to the aerial socket.

If I could tie a piece of sting to the cable, with a nut at the other end of the string as a weight, and push it through would that work (possibly with someone tugging the string at the other end)?

by **Steve the gas** » Tue Jul 22, 2008 7:02 am

Hi,
Is it steel conduit tubing perhaps?

Steve

by **ericmark** » Tue Jul 22, 2008 5:19 pm

If it is conduit than there are special nylon cables to assist with pulling cables through long speedo cable inner is best but hard to source. Second there are special lubricants like yellow 77 which will help for TV cable as long as you through away first few inches once through you could use washing up liquid but never use washing up liquid with mains cables as with electrical fault it can explode but TV will be OK. Soap and tallow are also used. The proper nylon cable has a springy bit at end and well worth expense from what I remember only a few quid.
Eric

by **andy2510** » Tue Jul 22, 2008 5:57 pm

Thanks for your replies.

Steve: it looks like copper piping more than anything else!!!

Ericmark: I'll try some form of lubricant and/or that nylon string.

I'll let you know how I get on (won't be till the weekend at least!).

by **kbrownie** » Thu Jul 24, 2008 11:57 am

Hi andy2510,
Does this conduit/pipe already contain an electrical circuit installed inside?
Couple of points that may need to be made!
If it's copper probally a gas/water pipe from an old now unused installation.
Another point is that as I understand it, Electrical Cable and coaxail/data cable should not be routed together and should be seperated if that is what you intend to do.
Regards
KB

by **andy2510** » Thu Jul 24, 2008 6:02 pm

Hi krownie.

The current wire is also a coax aerial cable.

by **kbrownie** » Fri Jul 25, 2008 11:27 am

That's okay then, just thought that you should be made aware of that,
Good Luck with install.
KB

by **sparx** » Sat Jul 26, 2008 9:42 am

hi Andy, ? does the existing coax move up/down in tube when pulled each way in turn? if so then usual way is to attach a draw wire to the outlet end and feed it through to loft, attach both coaxes to draw wire & pull back in making sure they go in without twisting!!!It needs a careful second mate though as it could pull off if not done gently.
good luck SPARX

by **andy2510** » Sat Oct 04, 2008 5:41 pm

Oops! Sorry - I forgot about this thread! :(

Took 6 hours, but I did it in the end (after losing the wire twice having to snatch it back it back).

What I did was attach a piece of old speaker wire to the old TV cable and new cable and pull through. Gave up on the 2-wire system and fitted a Splitter socket with markings for FM and TV instead. Got a good quality digital picture!