Wiring to an outside shed using cable troughs to avoid sewer?

[MartinOLondon]

Lots of good advice on these boards about external wiring, but I've not found anything similar to my problem ...

I plan to install a shed about 7 metres from the main house where the electrical run would be across a tarmac parking space and lawn. I can't suspend the cable due to trees.
The problem is that the trench will need to cross over a domestic sewer pipe that runs across my land, so the cable will either have to go above or below it (the sewer pipe is about 0.5m down).

Can I use shallow cable troughs with clip-on tops sunk into the ground?
This would be the same thing that rail networks run alongside their tracks and are strong enough to support vehicles. Cable will be SWA.

Apart from sourcing them, the two major problems I foresee are damp and rodents, but if the railways can cope with it ...?
This is the kind of thing I'm thinking of: http://www.cubis-systems.com/uk/products/cable-protection/mm-railduct/

Has anyone done something like this?

 

[JohnW2]

The problem is that the trench will need to cross over a domestic sewer pipe that runs across my land, so the cable will either have to go above or below it (the sewer pipe is about 0.5m down). Can I use shallow cable troughs with clip-on tops sunk into the ground?

Immediately above the sewer pipe might be just about deep enough but, if not, would it not be possible to excavate slightly under a short section of the sewer pipe and take the cable under it?

When one looks into 'holes in the road, it's not unusual to see one service provider excavating way under a pipe to put in their service!

Kind Regards, John

 

[MartinOLondon]

Thanks for your comment, JohnW2
Yes, I've often looked down holes in the road and seen the multiple pipes/cables crossing each other.

I just got excited about the idea of using these sub-surface cable troughs, as they
a: seem easier than digging a 0.5m trench (I'm really quite lazy)
b: safer, as no hidden cables
c: could possibly be used as a walkway
d: easy to add/replace cable, in the future

 

[mwatsonxx]

You're over engineering this. Can the cable run round the parking area in soft dig? You can get slots cut into the asphalt wide enough to take the cable and/or pipe sleeving.

 

[ban-all-sheds]

The trough will be fine, and as you say, has other benefits.

 

[JohnW2]

I just got excited about the idea of using these sub-surface cable troughs, as they a: seem easier than digging a 0.5m trench (I'm really quite lazy) ....

Anything which gave adequate mechanical protection to the cable would be acceptable, and these troughs would presumably qualify as that. However, as others have implied (and I imagine you realise), it is not approach that many people would consider in a domestic setting. As I said before, if you were going to dig a trench, then I don't think that circumnavigating the sewer pipe would be much of a problem.

However, it's obviously up to you.

Kind Regards, John

 

[JohnW2]

Cable will be SWA. .... Apart from sourcing them, the two major problems I foresee are damp and rodents, but if the railways can cope with it ...?

I forgot to say previously ....

... damp is certainly no problem. Don't forget that it is perfectly acceptable to bury SWA directly in soil. As for rodents, I would doubt they they could (or would want to) get through that stuff but, even if they did, they wouldn't get through the armour of SWA. Again, don't forget that it is acceptable to have SWA 'exposed' (e.g. clipped to a wall).

They do sound potentially expensive, though (even if one can get them in small quantities), I suspect more so than paying someone to dig a trench. Also, in passing ...

Next thing, it'll be running the cable inside a scaffold pipe!

Despite the spirit in which you made that comment, provided the inside was smooth enough not to tear the sheathing of the cable to bits as it was pulled through, that would probably be acceptable

Kind Regards, John

 

[John D v2.0]

Free advice, with a free flame war into the bargain.

Anyway to the op, it might be worth considering suspended cable support if you don't want to dig and don't have a permanent structure to attach to. Basically a specific suitable structure and you can tie the swa all the way along. The trench thing will be overkill and need too much space.

Edit Here is the link, although clearly you'd want a narrower tray
No idea why the image isn't working but see here
http://doubledirtydozen.com/images/77760/cable-tray-cable-ladder-cable-duct-pps.jpg

 

[JohnW2]

Anyway to the op, it might be worth considering suspended cable support if you don't want to dig and don't have a permanent structure to attach to.

.... I can't suspend the cable due to trees.

Kind Regards, John

 

[mattylad]

A scaffold pole may well be cheaper