Which cables to run to an office in the garden?

  RWBCAM 13:01 18 Jan 2006

I'm having an outbuilding converted into an office. Whilst a cordless phone and a wireless router might work, I fear there will be some degradation of signal.
The builder is putting in an underground conduit for an electricity cable, whilst he was doing this it would appear sensible to run extra cables to give me broadband for the PC and a telephone extension.
As these will be underground, will I need any special cables or will normal CAT 5 and a normal phone cable be OK? Are these the appropriate cables to use? And should they be screened.
Any input gladly received...Thanks

  Diemmess 13:35 18 Jan 2006

A conduit yes, but wiser to keep it for telecommunications only. If the mains cable is to run in a conduit then that should be separate, to avoid interference.
I have no idea what current legislation requires but not so long ago a suitable armoured cable for say 45amps didn't have to use a conduit.

  rmcqua 13:56 18 Jan 2006

BS7671:2001 (as amended) specifies the requirements, but it's a beast of a specification. The link below (albeit related to fishkeeping) might be useful.

click here

  Forum Editor 15:12 18 Jan 2006

the correct material is used. Some builders use plastic waste-pipe with solvent welded joints when running these conduits, and that isn't the right material. The best stuff for the job is a single unbroken length of blue polypropylene piping - the kind that's used for water mains. This is flexible and very tough, unlike waste pipe, which will crack under stress, and doesn't flex sufficiently.

Ideally you should have two conduits as Diemmess says - one for the power and one for communications cable. Armoured cable can be laid in the ground without any conduit, but if it's in a conduit it will be far easier to replace in the (unlikely) event of any problems. If you have a ADSL broadband service on a landline you'll only need to run one telecoms cable, but when I advise clients on these garden offices I always recommend that an extra one is pulled into the conduit as well - you never know what the future holds. It wouldn't be a bad idea to run a coaxial TV aerial cable in the conduit while you're about it as well.

CAT 5 cable will be good for up to 100 metres, and that probably covers your needs.

  wherty 16:54 18 Jan 2006

It might be prudent to add a cable for a burglar alarm which could be either part of or seperate to any house alarm.

  De Marcus™ 18:35 18 Jan 2006

The blue water pipe is what we used for the reasons FE stated, if the builder is going to be laying it, make sure you specify that particular pipe, because I'll gaurantee he'll use the thin grey or white drainage one if not told otherwise.

  hzhzhz 18:51 18 Jan 2006


youv'e recieved some excellent advice from FE and the members here. I used to do this sort of work for a living.

  rmcqua 20:07 18 Jan 2006

I'm not certain about this, so don't shoot me if you know otherwise, but I think the last amendment to the Wiring Regs. says that underground conduit must now be orange in colour.

  DieSse 22:49 18 Jan 2006

And don't make it too small - nothing is worse than trying to get multiple cables through a narrow conduit! There's always another cable you think of later!

  spuds 13:07 19 Jan 2006

Having just done this, I would say most points have been covered.Make sure that the builder lays the pipe's deep enough, so as to come out of harms way, unless you intend to place protection slabs on top.A further golden rule, make sure that easy 'closed' access at both ends of the pipe are allowed for future maintenance, and make sure the pipe's are larger than needed at the time being.

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