Trench Feet or Metres

Having just dug a 40 metre long trench for drainage from the house, about 1.5 metres deep, I'm not keen on the idea of digging another. Would it be madness to use the same trench for sewage, electricity supply to a barn via 40mm conduit and water supply to the barn?
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I would, but I would use armoured underground cable for the power.
Mike
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I'm bound by local building code and that does not permit armoured cable but does permit the use of polyethylene conduit.
I might just pull armoured cable through the conduit though.
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MuddyMike wrote:

yes. but be careful. You can bed water and sewage down in gravel but power cable should not be in gravel alone. Better to use sand.
And bear in mind sewers occasionally need digging up. so try and locate the mains as far as possible away..and tape over it.

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On 21/08/2011 18:37, Steve Firth wrote:

Are "drainage" and sewage" one and the same, or do you have separate systems for surface and foul water? If the latter, it is usual to put the sewage pipes at the lowest level so that if they leak you don't get sewage mixing with surface water.
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Cheers,
Roger
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Sorry for the lack of clarity, sewage and surface water are completely separate. The purpose of the trench was to connect the house to the septic tank which is near the barn.

Yes, sewage will be the lowest in the trench, but tiday threw a new problem, the sewage pipe has shrunk by about six inches during the day and had opened a joint - it's push fit corrugated 6" tube - I've not seen this before and I can only put it down to the current 40C noon temperature. Nothing else has changed in the 24h since the drain was laid.
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On Sun, 21 Aug 2011 20:19:15 +0000 (UTC), Steve Firth wrote:

Ah, you've been caught short!
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Peter.
The gods will stay away
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snip

:-)
Presumably the pipe expanded with the heat, extending the overall length. When things cooled down, the joints weren't strong enough to pull the full length back up a steep slope as you mentioned earlier?
Perhaps the corrugations prevent this happening when the trench is back filled.
regards
--
Tim Lamb

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Steve Firth wrote:

What country is this? Your said "no armoured" impying it's not the UK... and I find a building code that prohibits armoured rather than requiring it to be very weird.
OTOH for electrics, if you are in the EU, AFAIK you *could* do it to IEE standards as long as the whole circuit is done that way... of course, a warning sign on the CU stating the fact would be courteous...
Me? If the drains are going at the bottom of the hole, It's back fill to 1m deep, then lay the water and electric at that depth either side of the trench, then backfill 30cm then warning tape, then fill over.
What cable are you "supposed" to use? Does it require ducting?
Cheers,
Tim
--
Tim Watts

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It's in Italy, where "safety" includes not distinguishing live from neutral. The electrician is insisting that 40 metres run of cable does not need to be more than 2.5mm^2. I'm over ruling him on that one. However he insists that burying armoured cable without conduit is "illegal".
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Steve Firth wrote:

Ah. And that is the case in many EU countries... Even in the UK, neutral is now termed as a "live" to break the associaion of it being "safe".

What sized supply are you running to the workshop? 2.5mm @40m is going to have a practical limit of about 8A for a circuit supplying lighting due primarily to volt drops - but there also remains the question of whether an MCB or fuse will even clear with a dead short on the load end - or at least whether it will clear in 40mS (unless we class this as a distribution circuit and have local MCBs/fuses in the workshop - or RCD protect the circuit). Sorry - do not have my books to hand right now...
For a 32A W/S supply, I'd be looking at 10mm2 over that sort of distance. What sort of circuits are you installing and total load?
This is of course IEE 17th numbers - but although the regs may be different, physics doesn't change a lot between UK and Italy.
One of the other big impacts with be how the earthing is supplied to the workshop - local earth rod?

I agree... Have a look at http://www.tlc - direct.co.uk/Technical/Charts/VoltageDrop.html
It's not perfect - does not allow for different breaker types (B vs C vs D) but it will be a reasonable rough guide.

I suppose if you have a local bod doing it, he will have to do it to local regs - but there's no way he can complain about beefing up the spec.
Perhaps their "armoured" is built to a different design than ours and genuinely not rated for direct burial?
If you don't mind the dosh - bury a couple of flexiducts (sort used for traffic lights etc - comes in big coils) - one for mains and one for pulling through all manner of intresting other services and leave a rope in and maybe 1-2 intermediate small manholes.
Cheers
Tim
--
Tim Watts

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On 2011-08-21, Tim Watts wrote:

...
That's possible. IIRC, in the USA there is a distinction between the normal equivalent of PVC twin & earth cable and "UF" (underground feeder) cable. The former is not supposed to be used underground, even in conduit; the latter has mould- and mildew-resistant outer insultation.
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Adam Funk wrote:

Most sites I could find do seem to concentrate on installtion using conduit/tubing/mechanical protection methods, but this shows a direct buried armoured cable (with a marker above)
http://www.elektro.it/cavi_interrati/cavi_interrati_01.html
Might be useful for starting an argument with your sparky!
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On Tue, 23 Aug 2011 08:18:47 +0100, Adam Funk wrote:

Yes, I'm not even sure if I'm allowed to use any kind of armo[u]red cable underground where I am in the US; I can bury 'bare' cable, or I can use conduit (and I think that conduit has to be 12" deep or more, and 'bare' wire 24" or more).
cheers
Jules
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Jules Richardson wrote:

extraordinary.
surely the 'bare' cable IS armoured?
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On Tue, 23 Aug 2011 15:27:39 +0100, The Natural Philosopher wrote:

No, I don't believe so, at least not with anything that'd survive an impact with something like a shovel; I suppose they just rely on it being deep enough to be out of the way in most cases :-) (there is a requirement to use conduit on the verticals where they enter/leave the ground, just not for the horizontal sections)
They're very big on calling in location services here before digging, with good reason :-) The last few times I've done that it's been a quick form on a website and all the utilities companies show up in a few hours and use their gadgets to mark out where their services run.
At some point I need to run new wire up to my workshop (so I can have 220V up there rather than 110-only), but I need to look into the rules as it'd be nice to just have some form of service trench so I can run network, phone and water up there, too - and add other stuff at a later date if needed.
cheers
Jules
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