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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> laying utilities to a garden outbuilding https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1090417686 Message started by Mr_Ed on Jul 21^st, 2004, 2:48pm

Title: laying utilities to a garden outbuilding
Post by Mr_Ed on Jul 21^st, 2004, 2:48pm

I' building an office / workshop at the bottom of the garden. I need to lay electric, water and phone supplies about 20 metres.

I'm happy enough to use armoured electric cable in an 18 inch deep trench, but for belt and braces was planning to feed it through a plastic conduit.

My question is this. can i feed to phone cable through the same conduit or will there be interference? if so how far apart do the cables need to be?
???

Title: Re: laying utilities to a garden outbuilding
Post by HandyMac on Jul 21^st, 2004, 3:11pm

I believe the requirement is 50mm (2in).

You must not run telephone/data cables in the same conduit as mains. This isn't so much a transmission issue, but one of safety.

Andrew

Title: Re: laying utilities to a garden outbuilding
Post by Lectrician on Jul 21^st, 2004, 5:11pm

Dont use conduit. Use proper electrical DUCTING, continuoes legth on a roll is best, no joints to snag on.

Title: Re: laying utilities to a garden outbuilding
Post by plugwash on Jul 21^st, 2004, 6:05pm

you can run them as close as you like if they are in seperate ducting

so one duct for mains one for phone and one for water

water needs to be deeper too iirc

Title: Re: laying utilities to a garden outbuilding
Post by rabbit_rabbit on Jul 21^st, 2004, 7:28pm

Interesting Plug - I thought that the Water Regs (for MDPE) was same as IEE for cables - 750 mm.

RR

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 21^st, 2004, 7:48pm

was gonna say 18" is not deep enough for cables, however im not gonna tell some one to dig it more than 18" deep unless they ask, im not doing the digging!!

750mm sounds more like it or 650mm min

Title: Re: laying utilities to a garden outbuilding
Post by supersparky on Jul 21^st, 2004, 7:59pm

there is no minimum for cables people- its interpritation unless he is having a seperate new metered supply to his shed.....would have thaught it was a submain from house...

ss

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 21^st, 2004, 8:17pm

we were taught minimum depth for SWA cables was to be 650mm, from top of cable too

Title: Re: laying utilities to a garden outbuilding
Post by Lectrician on Jul 21^st, 2004, 8:46pm

to be buried at a depth that will prevent unintentional damage (or some wording such like) :-)

Title: Re: laying utilities to a garden outbuilding
Post by rabbit_rabbit on Jul 21^st, 2004, 8:56pm

Sure there is SS. I wont do a CPW BUT 16th Regs its 750 mm.

Having said that, and my Bible is in the van not here, if I recall its 750 mm beneath area that can be cultivated.

I hope so coz the last one I did was bury SWA in a driveway and it was an AWFUL job digging rocks and boulders, even used my DW and chisel! I gave up in the end and its all of 10" down.

RR

Title: Re: laying utilities to a garden outbuilding
Post by supersparky on Jul 21^st, 2004, 9:02pm

no, i thaught the minimum was removed, infat im 99.9% sure that it has been.
lectrician is about right with the wording, its upto you to decide

ss

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 21^st, 2004, 9:12pm

well thats crazy, people wont bother burrying it sufficently deep, and say its "to be buried at a depth that will prevent unintentional damage" how can u define that, only have to look at a good size spade! ::)

Title: Re: laying utilities to a garden outbuilding
Post by supersparky on Jul 21^st, 2004, 9:48pm

not if your any good LS not gunna stick a cable at 2inch under a flowerbed are ya!!!

only place ive seen cables at 750mm was when the rec dug up the street by a sub near where i used to live, and that was 11kv swa

ss

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 21^st, 2004, 11:11pm

wrote on Jul 21^st, 2004, 9:48pm:

not if your any good LS not gunna stick a cable at 2inch under a flowerbed are ya!!!
ss

no, id dig up lawn instead, or just do the easy approach and clip direct with cleats ::)

Title: Re: laying utilities to a garden outbuilding
Post by ChubbyPhaseWire on Jul 21^st, 2004, 11:24pm

Cables to be installed in ducts or pipes in the ground
are not required by BS 7671 to have armouring and/or
a metal sheath, if the duct or pipe is sufficiently
strong to resist likely mechanical damage. In case of
doubt, a cable fulfilling the requirements of
Regulation 522-06-03 should be provided.
Protective conductors which are buried directly in the
ground must comply with the requirements of
Regulation 542-03-01.
All buried cables must be marked by cable covers or a
suitable marker tape, and buried conduits or ducts
must also be suitably identified. A warning tape
above the duct or conduit run would be suitable.
Cables, conduits and ducts must be buried deep
enough to avoid being damaged by any disturbance
of the ground reasonably likely to occur. This could
include gardening/horticultural works, excavating for
any local buried service pipes etc. Generally, it is better
to locate cables etc. clear of such possible works.

A depth of burial of less than 500 mm is usually
inadvisable as shallow laid cables may be
inadvertently damaged by general gardening etc.
Cables that cannot be buried at a reasonable depth
should be specifically protected, e.g. by ducts encased
in concrete, or installed along an alternative route.
Before any excavation is undertaken for cable or
other works HSE guidance booklet HSG47 "Avoiding
danger from underground services" should be
studied, as it provides valuable advice on safety
aspects.
It is important to be able to identify exactly where
hidden services are located and accurate records,
including drawings, should be made before trenches
are backfilled. Cable routes should be located on
drawings by dimensions from some fixed object that is
not expected to change for a considerable time, (e.g. a
building). Road and pathway features may be relatively
easily changed. Scale drawings are of little value unless
very detailed. Concrete route markers may be installed
at changes of direction of cable routes and at regular
intervals along routes. ;)

PS Where is the fcuking kek to the front door wabbit

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 21^st, 2004, 11:43pm

there we go then, LoL!!! :D

Title: Re: laying utilities to a garden outbuilding
Post by Mr_Ed on Jul 22^nd, 2004, 3:06pm

Cheers peeps,

I guess if I collate all the advice and use the most stringent - I'll come to no harm.
so it looks like a trench three feet deep - three feet wide with 2inch thick concrete pipes spacea at least 12 inches apart with an itty bitty caple (or pipe) in each.

I think I'll move the workshop a little nearere the house :-/

Title: Re: laying utilities to a garden outbuilding
Post by scotspark on Jul 22^nd, 2004, 10:57pm

thot it was 18" or 450mm as that was a spade and a half deep

and make sure youcover with warning tape and lay on a bed of sand then backfill wi sand

depends where you are running the cables I suppose but don't see there being much of a hazard to cables at 450mm deep in your average back garden

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 22^nd, 2004, 11:55pm

regs has softned up now on the depth it seems, just have to ensure no spades are likely to penertrate it, and since it is just a back garden, not likely to be any excevation, as long as you keep time team out!, no ones searching for roman remains in my back garden! ::)

Title: Re: laying utilities to a garden outbuilding
Post by plugwash on Jul 23^rd, 2004, 12:21am

generally time team geophys before they start digging

so i expect they would find your cable before they start doing any digging

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 23^rd, 2004, 12:25am

We're all safe after all! ;D

Title: Re: laying utilities to a garden outbuilding
Post by supersparky on Jul 23^rd, 2004, 12:27am

for gods sake it was a simple question.
all he/she needed was a simple answer, not a debate on regs.

ss

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Jul 23^rd, 2004, 12:48am

lol, he didnt ask for depth anyway was asking re segregation, but depth didnt seem enough, arh well ::)

Title: Re: laying utilities to a garden outbuilding
Post by scared_of_diy on Aug 2^nd, 2004, 10:26am

Although related this response is on a different tack.

I believe if you plumb water into a seperate building then it becomes subject to planning permission from the council and the dreaded council tax.

Electrical is fine no planning permission is required. This may vary from Council to council. I know this because I went through a similar excercise and gave up after trying to fight the council!

Title: Re: laying utilities to a garden outbuilding
Post by L.Spark on Aug 2^nd, 2004, 10:00pm

that might be handy to know, thx :P