Is the electric trench OK?

[JoceAndChris]

So I nipped off for a day with friends yesterday and came back to this:

It's two foot deep. Just wondering if you think my plan is sound - run the cable from the consumer unit on the other side of the building up through the attics and then out through the music room wall seen on the right side in this photo and to the pond:

Once the pond is pumped filtered and illuminated I'd like to then run another trench from the pond to the gate to have a light there - might that be feasible?

A qualified electrician to do this - if I can find one who is prepared to work in our attics. Many thanks for any input.

 

[Flyfisher]

Good progress!

I'm pretty sure all external wiring needs to be certified so, yes, a qualified electrician is going to be required. If it was me, I'd call the electrician I use to check about cable types and discuss how and where I was planning to install it all, I'd then lay the cabling in place but get him to do the final connection and certify it all. If you don't have the discussion beforehand (or know the electrician well) then they might not be keen to certify anything they haven't seen or previously agreed to.

I'm sure the trench will be deep enough for the cabling. As I understand things, external cabling must be armoured anyway and can be laid on the surface if necessary, so I can't see any problems with a deep trench. I'm not sure if it's a certification requirement, but it's certainly good practice to lay an identification tape about 6 inches above the cable though to help avoid future accidents with enthusiastic digger drivers. This is the sort of thing and it's widely available: http://www.amazon.co.uk/CAUTION-ELECTRIC-CABLE-WARNING-UNDERGROUND/dp/B0071YUQCA

Our stripey friend should be able to confirm the official position.

 

[Zebra]

The Regs don't state a depth, they just say it has to be appropriate to the circumstances, or some wording like that. We normally do a foot, with the warning tape as FF suggests. Of course, it has to be Steel Wire Armoured cable, which might be unfeasible to have running through the loft, it's quite stiff, so there may have to be a join on the wall of the house, or in the loft just before the cable exits.
You'll have to think about how you want to switch the light at the gate, before you install the wiring. If it'll be switched from the house with the pond pump lights then fine, but if you want to switch it separately you'll need to add an extra core to the cable before you start, ie four-core rather than three-core, to carry the extra switched live.

 

[Flyfisher]

. . . it has to be Steel Wire Armoured cable, which might be unfeasible to have running through the loft, it's quite stiff, so there may have to be a join on the wall of the house, or in the loft just before the cable exits.

When we had a new meter installed, I had it installed in the outbuildings so that we didn't have one of those ugly boxes on the house. This meant running an armoured cable from the meter to the consumer unit in the house. The cable is almost 1.5 inches in diameter and so heavy that the drum it was delivered on needed two people to manhandle it as well as a special stand to allow the cable to be pulled off! We did manage to route it through the walls and attic without requiring junction boxes, though it wasn't an easy job.

This photo shows the incoming cable top-right. There is also another armoured cable coming out of this consumer unit, which connects to another consumer unit in the new kitchen. It's a much thinner cable, but still larger than the cable Joce will probably need, so I'd be hopeful that installation won't be too onerous.

 

[Owain]

I'd suggest an above-ground enclosure near the pond to split the feed to the pond and to the gate.

Do everything in smooth internal wall ducting so other things can be blown through later. You might want electric gates or an electrical speaking tube to the gates.

Also at the pond you might need a 24hour supply for an aeriating pump and a switch supply for fountain or lights. You can avoid having to run multiple cores if you use something like X10 over mains control, but this will need space for the receivers in the outside box.

 

[JoceAndChris]

Thanks so much for all the excellent information you've posted. I had no idea the cable was so thick! Chris was the one who said the trench would haver to be 2 feet deep - silly Chris! He picked that up on some website, and it's made a proper mess. Oh well - better over-catered for than under - I wanted to use the digger whilst I had it as our soil is rocky and difficult to do by hand.

Thanks for helping me think over what I want, an electrician is supposedly coming to quote and it's so helpful to not be completely clueless. I think I want the pond light and the gate light on a PIR sensor but the light for the illumination of the front facade (I want it lit like Lincoln Cathedral!) should be on a timer.

Good point Owain about future needs - our gate is the original one and I wouldn't wish to see it too modernised, but a light there would prevent my friends tumbling over after I had plied them with wine which is what happened last time - I was mortified I'd let them walk through the dark fields in that state! A big 19th C style street lamp here would be good to throw a light for the dog walkers and everyone else.

 

[Flyfisher]

. . . but the light for the illumination of the front facade (I want it lit like Lincoln Cathedral!) should be on a timer.

Just a thought about timers for outside lights. I like to have them come on at dusk and, in the winter, to come on in the morning until the sky brightens up, but I don't want them to be on all night and I don't want to have to keep adjusting the timer as the dusk and dawn times change throughout the year. I've never found a single timer/light sensor that can do that but I've successfully used a separate timer and light sensor to achieve the same thing.

Basically wire the light sensor to control the lamp(s) so that they will come on at dusk and go off at dawn. Then wire the timer so that it only supplies power to the sensor & lamp for the times you want the lamp(s) to light if it is actually dark. It may be easier to think of using the timer to define the 'off' time.

For example, I wanted the lamp(s) to come on at dusk, go off between 12am to 7am and then come on again until dawn. To achieve this, set the timer to only come on between 7am and midnight. In the summer, the lamp(s) will come on at dusk, go off at midnight and not come on in the morning because it will already be light enough by 7am. In the winter, the lamp(s) will also come on at dusk (much earlier than in the summer of course), go off at midnight, then come on again at 7am until dawn brightens up the sky and the lamps turn off.

It might sound complicated but it's very easy to do, if planned for, and means that you never have to fiddle with timers during the year to adjust the on/off times as the days lengthen and shorten.

 

[Roger H]

Bit late for this job but you can also hire a 'mole man' to burrow a route for a cable without disturbing the surface. Mine ran a route for a gas pipe under tarmac for 20m@<£150.