Outside Cable

Joe100w · Posted: Fri Sep 25, 2009 6:03 am Post Subject: Outside Cable

I am running some armoured cable to some garden lights. Is there any rules as to how deep they need to be under the grass and if they need to be protected. This cable will run off an RCD.

Also will need to split the cable to supply different light to different areas - how best to do that.

Thanks

ericmark · Posted: Fri Sep 25, 2009 7:13 am Post Subject:

522.8.10 Except where installed in a conduit or duct which provides equivalent protection against mechanical damage, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both, suitable for use as a protective conductor. The location of buried cables shall be marked by cable covers or a suitable marking tape. Buried conduits and ducts shall be suitably identified. Buried cables, conduits and ducts shall be at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground.

I would consider 18 inches would comply but the regs don't give a distance.

As to joints there are scotch cast joints able to joint cables below ground but the norm would be to daisy chain and join above ground. Unless libel to flooding an IP44 box is normally good enough above ground with drain which would include the base of a lamp standard.

If you are likely to be flooded then IP68 will be required.

If the garden is attached to domestic premises be aware that Part P will need satisfying.

stargazer · Posted: Fri Sep 25, 2009 7:41 am Post Subject: Re: Outside Cable

Joe100w wrote:

Also will need to split the cable to supply different light to different areas - how best to do that.

I like these

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Joe100w · Posted: Fri Sep 25, 2009 5:58 pm Post Subject:

stargazer

What are the red connectors in the connection box. I am not familiar with them. Thanks

properleckie · Posted: Fri Sep 25, 2009 6:15 pm Post Subject:

the red items are insulating sleeves over the 'line-tap' connectors which can be purchased with the 'pratley' underground joint box shown.

RF Lighting · Posted: Fri Sep 25, 2009 7:16 pm Post Subject:

I personally don't rate pratley boxes at all....

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ban-all-sheds · Posted: Fri Sep 25, 2009 8:16 pm Post Subject:

Why not?

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Lectrician · Posted: Fri Sep 25, 2009 8:32 pm Post Subject:

Nor me.

If you are going to joint a cable underground, it is likely to be permenant. Wht use a dismountable enclosure?

Just resing joint it - FAR cheaper, and FAR more reliable.

I have never used the pratley boxes, but they bug me. Nothing is water tight under ground. (except a well done resin joint).

Smaller SWA is not that expensive these days, and looping even some distance is not likely to cause that much extra expense, especially when you consider jointing.

Looping also gives you the chance to fault find easily in the future some years down the line.

Preferably you would use lights which accept the looping of SWA, these are unfortunately usually very expensive. The next best thing is a light which has the space to include a GALV trouser box in it's column/enclosure. If you cannot achieve this, a joint at each light is required. An IP rated plastic gewiss type box is good if you can hide it in shrubbery, or dont mind seeing it, otherwise a UG joint, preffereably resin, is needed at each light.

RF Lighting · Posted: Fri Sep 25, 2009 9:44 pm Post Subject:

I went to a job where pratley boxes had been used underground. They were all full of water.

Resin joints are the ONLY joints which actually work underground.

Above ground there is no need for a pratley box. A galv conduit box is fine, and they are cheaper and look neater.

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ban-all-sheds · Posted: Fri Sep 25, 2009 11:01 pm Post Subject:

Were they the underground type, or the overground ones that stargazer linked to?

If the ones that the makers say are suitable for burial aren't, how come they are on sale? How come nobody selling them gets prosecuted? Why does a company like Pratley, scarcely a newcomer to the market, say that their products are suitable for continuous immersion down to 2m if they are not?

They also sell JBs which they claim are certified for use in explosive atmospheres - is that a lie too? The consequences of that could be catastrophic.

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Joe100w · Posted: Sat Sep 26, 2009 9:27 am Post Subject:

Lectrician
What is the resin joint and where can I find more information about the different joints that can be made - nowadays.

ban-all-sheds · Posted: Sat Sep 26, 2009 11:23 am Post Subject:

Other brands and other suppliers are available.

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ColJack · Posted: Sat Sep 26, 2009 3:47 pm Post Subject:

alternatively, you can get some waterproofing "gel" that you can pour into the above boxes ( or the underground ones ) to make double sure they are watertight...

the joint shown is a straight connection.. for lights you would need a joint for 3 cables.. which TLC don't carry by the looks..

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