Armoured Cable Installation

Hi there, 

I'm currently building an outhouse in by back garden. I want to have lights and plug sockets out there eventually so that I can use it as an office. 

I've had a quote from an electrician but what he recommends sounds a little odd to me...

Basically he asked if have have RCD's on my consumer unit. I told him that I do. He then proposed to run an armoured cable from one of the sockets in the house out to the outhouse above ground along the edge of the garden, installing an RCD in the outhouse.

This seems a little odd to me. I have no training, but I would have thought that you'd have to run a separate power and lighting cable straight from the consumer unit underground to the outhouse. 

Could someone explain to me the correct procedure to me. 

no point running multiple cables to outhouse when you can install 1 and a small consumer unit, then add more to it as you like in future

Hi, the normal procedure would be to do a site visit to establish the type of supply you have. This can effect the way the cables are installed and earthed.

You would only need one supply cable to the outhouse, then a simple four way consumer unit can be installed there for the distribution of final circuits.

The best way is to bury the cable, its neater and more time consuming which is why some will install the cable on the surface beside a wall or fence.

I would not take the supply from a socket in the house, I would take it from your existing consumer unit/fuse board.

I hope that helps a little.

Manator said:

Hi, the normal procedure would be to do a site visit to establish the type of supply you have. This can effect the way the cables are installed and earthed.

You would only need one supply cable to the outhouse, then a simple four way consumer unit can be installed there for the distribution of final circuits.

The best way is to bury the cable, its neater and more time consuming which is why some will install the cable on the surface beside a wall or fence.

I would not take the supply from a socket in the house, I would take it from your existing consumer unit/fuse board.

I hope that helps a little.

Click to expand...

1. Why would you take it from the CU?

2. How would you bury it and how deep? The cable is armoured so would it need any further protection underground? Would I need to mark the route the cable travels somehow?

Your electrician should be able to answer all those questions for you.

Hi There,

As is stated in the above post, run the cable direct from your consumer unit in the house, underground to the shed, where you will have another consumer unit from where you can run anything you like..

Only an idiot would run the cable next to a wall or fence or anywhere on the surface of the ground, as it is obviously going to; 1, look like a muppet installed it, and; 2, get damaged in future..

It will cost more to have it done the proper way, but if you do it the silly way, you will only have to pay to do it the proper way when either it gets damaged, or you try to sell your house, and the surveyor spots it and the purchaser then makes you drop the price..

john

Mara Jade1992 said:

1. Why would you take it from the CU?

Click to expand...

becuase its a better wya to do it

Andy™ said:

becuase its a better wya to do it

Click to expand...

Why?

Mara Jade1992 said:

Why?

Click to expand...

connect it as a spur and your limited to 13a. and if you use the full 13a then thats 13a less from your other circuit its conencted to.

Hi Mara,

You would run it from the CU as that is the proper way to do it. If you just come off at a socket or whatever, you will be limited to 13A or about 3000 watts of power in your shed. Consider what a heater will use, and then boil a kettle... With me!!

Secondly, there is no fixed depth to bury it, the regs just state at a depth where it is not reasonably forseeable that it will be damaged. I would suggest about 500 or 600 mm. As to marking the route of the cable, this is a requirement too, and you can buy a roll of yellow marker plastic tape [about 100mm wide it is] to lay in the ground about a foot above the cable. It says on the tape "warning buried electric cable" or somesuch.

hope this helps..

john

Ok, that makes sense, thanks guys. 

As already said many times, run the SWA from the CU to the outhouse.

IT should be burried a minimum of 450mm deep, with yellow "warning electrical cable" tape laid above it before filling the trench.

In a job like this, a large part of the labour will be digging the trench and burying the cable.  One way you can save money is to get your electrician to specify and supply the cable, for you to then bury it, and your electrician to come and connect it.

You would need his agreement to work like that, but since it seems he's not interested in burying it, he would almost certainly agree.

I have to say, the advice he has given so far would make me want to go and find a different electrician.

If you're looking to save a few bob on the job, you could trench it and lay the cable from A to B  yourself .  Leave whatever the sparks says at each end .

Sometimes this type of job gets silly because you are paying an electrician to dig a trench .  Bit like asking Michaelangelo to paint your house.  ( He,s crap with a roller anyway)

Presuming the route is over dirt or grass.

If concrete then above ground might be easier unless money is not an issue.

Underground can be neater as its hidden, but also a big hassle if the ground is masonry or complicated.

I agree with what the others have said,

One pendant or 5ft tube and a socket to run the garden strimmer or battery charger may be all that is required.  Not everybody runs industrial welders and the like.   So a cable as a spur from a nearby socket maybe more than adequate for the foreseeable requirements.

But if you want an installation that can run a fabrication factory or something then im sure your electrician would be more than willing to fit it knowing that he should have a much larger pay packet forth coming.

erm... to be used as an office... so i can easily imagine a 3kw heater in there over winter. then the lights. then the computers / printers etc... so can easily be over 13a for the 'forseeable requirements'

Don't forget the kettle as well.

office................ye fair enough dint see that

Before you even worry about how to get the cable down to the shed you will need to think of how to get FROM the cu if you go that way. Often the cu is at the front of the house and the shed at the bottom of the back garden. MANY, MANY options, none as "easy" as spurring off a socket which is why many choose the "quick" route:

- Down from the cu then under a raised floor, across the house to the back wall. Laminate and tiled flooring make it more difficult.

- Up from the cu, between floors then down the back wall - of course, as with downstairs you may have  issues of again laminate flooring, fitted carpets, furniture, beds to move etc.

- Up from the cu, into the loft across and then down the back outside wall.

- Out through the wall from the cu then clipped to the outside wall all the way to the back of the house.

Only just the other day a friend who is an ELECTRICIAN (has 5 kids btw) was moaning that he had lain a length of 6mm sq. armoured along the base of his fence to the summer house at the bottom of the garden where they have a big TV etc and use it as an extension of the house. One of the kids was cutting the lawn and went THROUGH the armoured with the mower! Just because it's armoured doesn't mean it shouldn't be protected!

Lots of ways to skin this cat but if you choose the "easy" option you may well regret it later. Going direct from the cu with the shed on it's own circuit WILL give you more capacity down there etc. As above, a scenario might be that you switch the heater on one cold evening as you plan on working in there later. Hubby etc decides he'll just finish mowing the lawn, shredding those branches etc. Straight away you're over 13A!

No pain, no gain etc!

IF you go underground you might even consider running the cabling in it's own ducting (another "tube") and even think about running a CAT5/6 cable(s) for any computer down there if your WiFi won't reach. Intercom (although there are ones that run over the mains)? CCTV (again there are wireless options.........)?

The "list" is endless! Not trying to scare you just pointing out things that others have learnt from experience!

As its a lady who may be using this outbuilding as an office she will probably require 12kW of heating  ]