Cable, conduit, multi utilitiesTrench question.

[Welski]

Not sure where this question should live!!!


I'm in the (long) process of building a swimming pool in my garden (so much for the maker's claim of swimming in 7 days!)

Anyway I've just finished digging a 15m long trench which will carry a 35mm copper gas pipe and a 110mm soil pipe both of which will serve the barn we intend to use a changing room and pump/heater room for the pool.

The house is very old (as is the barn) and the electrics are, shall we say not 21st century! -The barn will need a complete upgrade.

I have a couple questions relating to the electrical side of things

1 Can I use the same trench for the electrical cable if so does it have to go deeper than the 375mm gas pipe? (the trench runs up my gravel drive)

2 What cable should I use ? (It will need to power the electrics for : a 250,000BTU gas heater, a 0.75HP electric pump, a 10 kw shower, 5/6 assorted low demand sockets and a lighting circuit -the barn is about 30mx10m in area)

3 If I need to get an electrician to lay the cable can I install a conduit now for him to use later ...if so how deep does it need to be?

4 At the house end of the cable run it will need to go up the outside wall of the house to the first floor level. I'm assuming it will be a very substantial cable so are their any issues I should be aware of here?

5 Can I do any of this work without breaking Part P regs (ignore this last one if its too wide an issue!)

I really would appreciate any assistance with this as the trench has been open a while now and I dont need any more rain!


Many Thanks in advance for any advice. For the sake of my poor back: PLEASE TELL ME I DONT HAVE TO DIG ANOTHER TRENCH

 

[dw3101]

you cant run a plain old copper gas pipe in a trench.. But im sure you know this..

How wide is the trench?

 

[mrwe11s]

Electric cable should be 400mm below ground level

it can be in same trench as plastic yellow gas main pipe

as to the size of cable this will depend on the length of run to the house fuseboard i would be happy to advise

 

[ban-all-sheds]

Cable will be 16mm² minimum.

Part P does not apply, as you started all this last year, didn't you....

 

[Welski]

I've got one of the Queen's pet animal people coming round to install the gas pipe/do all the connections etc. I was assuming it would be a copper gas pipe! But he will know what he is doing (I hope!)

DW3101 What sort of pipe will he use? I was told by the people who supplied the pool gas heater that the pipe would be copper and must be 35 mm to feed the 250k BTU heater (and buried at 375mm)
At the moment the trench is about 9 inches wide but I can increase it


mrwe11s OK so it needs to be the first thing I lay in the trench once I dig a bit deeper! If the gas pipe is going in at 375mm how much infill should I leave beneath this and the cable or can they be in contact? The length of run from the propsed location of the consumer unit in the pump room to the one in the house is (approx) 25 metres (max) Can you advise on the type of cable and whether it is prudent to install it in a conduit. I am going to get an electrician to do the connections etc but I really need to 'backfil my chasm' this weekend!

ban-all-sheds 16 mm min.. ok even at 25 metres? I don't mind spending a few quid extra on cabling if it means 'future proofing' demand; I really don't want to be digging my drive up again!

Oh and yes I commenced work on this years ago ....it's ALWAYS been my dream to own my own pool and I've been planning for it since I was 10. (do you think that would stand up in court? )

Thanks for all the help.

 

[kevplumb]

Electric cable should be 400mm below ground level

it can be in same trench as plastic yellow gas main pipe

as to the size of cable this will depend on the length of run to the house fuseboard i would be happy to advise

with sutiable spacing

last pool i worked on i fitted a 24 kw system boiler on 20m of 28mm


it must be some pool mate

and some boiler

 

[Welski]

Hi Kev

Yes I got a bit carried away when I hired the 3.5 ton digger...I took a week off work (I'm a banker -no comments pls) to dig a small hole for the plastic panel kit. Unfortunatley I got 3 foot down and the digger sank another 3 feet into the ground 3 days later I had a rather deeper hole than I intended. (and a rather muddy digger to wash)

Upshot is the pool is not quite so shallow now ! Hence the huge heater > :http://www.poolstore.co.uk/ishop/691/shopscr403.html

BTW thanks for the help re the waster pipe problem over on Plumbing...this damn pool I wish I'd never started

 

[dw3101]

Check with the installer, but its more likely to be plastic coated copper..

Gas pipes that go through a wall have to be within another pipe AFAIK.

I would have thought it would be more like MDPE water pipe than Copper??

What do I know though.. just dont want you to have to do it twice.

David

 

[Welski]

Check with the installer, but its more likely to be plastic coated copper..

Gas pipes that go through a wall have to be within another pipe AFAIK.

I would have thought it would be more like MDPE water pipe than Copper??

What do I know though.. just dont want you to have to do it twice.

David

Cheers David...Sounds like you've dug a trench before too?

 

[dw3101]

I have.. its not that hard if you know how to dig a hole though

You know what i mean by that.. IE Dig a hole and then dig into it..rather than trying to stab horizontally.. anyway... Mini diggers are hard too especially if you cant move left and right hands independantly.

Had to dig the foundations for my garage extension shown here..

1.5ft deep

Then floor was dug out after.. Our front garden is now around 1ft higher all over

David

 

[Welski]

Blimey I bet that took the paint off your new shovel!

I know what you mean about mini diggers....look at the mess I made of this!

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Before the digger sank the bottom was nice and smooth I SWEAR!

(Sorry about getting off topic )

 

[Welski]

Mind you I got there in the end.....when I finish the grouting/sort out the heater etc etc etc etc

 

[mrwe11s]

Should run SWA cable in bottom of trench then back fill

16mm will be large enough for the load you have listed

if you are using SWA run from an RCD in the house

 

[plugwash]

NO

without knowing the distance involved its impossible to say if 16mm is sufficaiant

 

[ban-all-sheds]

Anyway I've just finished digging a 15m long trench

ban-all-sheds 16 mm min.. ok even at 25 metres?