Power to shed query

hesker

I'm thinking of building a workshed next to the house and I'm doing up some rough plans before I talk to electricians.

I like the idea of putting a separate CU in the shed. General advice on here is to run a SWA from the CU in the house to the CU in the shed. I'm wondering how is this done. I'd like to do as neat a job as possible and in compliance with regs so what are the approaches

1. Run a SWA down the internal wall from the CU in the house and then out through the front wall of the house. Then along the bottom of the wall and bury in garden and route to the shed in a trench. Don't like this at all really as cable will be visible for much of the length. Even if boxed in it will still not look neat.

2. Try to fish the SWA along the same route from the CU in the house out to where the ESB meter is located and from there to the shed in a trench. This would be visibly much neater but is it practical to do or even safe to have 2 cables side by side like this routed from the house CU to the meter cabinet.

3. Run a cable from the meter cabinet direct to the shed. This would be the neatest I think but not standard it seems. This thread [ http://www.boards.ie/vbulletin/showthread.php?p=61762725 ] discussed this option but no real clarity was reached.


Here is a diagram showing rough plan. You can see how the shed is located to the side of the house and conveniently near the meter cabinet.

Carlow52

If you were to take it from the meter, this would mean that the seals on the meter would need to be broken to allow the second set of tails be put into the meter along side the existing tails which are probably 16sq so there may not be room.

You only need SWA when it is exposed outside, ordinary PVC PVC will do internally. Could you run it across attic?


Option 2 would be very tough to do

hesker

It's a 2 storey house so I would have to fish up into the attic and then down to the meter cabinet. Might be equally difficult as 2.

I can post a photo of the meter and connections if it will help

M cebee

there's no confusion

sub-mains(garage supply) don't come from the meter cabinet

hesker

Great. That rules out 3 then.

So is 1 or 2 the usual approach or is it up into attic and down again?

Carlow52

Get a second meter in the meter box for garage

Bruthal

hesker wrote: »

Great. That rules out 3 then.

So is 1 or 2 the usual approach or is it up into attic and down again?

I have never run a cable from an MCB board to a shed via the attic yet, but that does not mean its not a possibility.
Sometimes i have removed the skirting board below the MCB board and routed cable down the dry lining and out at ground level and underground. How much concrete you have to cross is the thing as a notch would have to be cut across it.

Is it concrete all the way around the side of the house to the shed? Often there is soil along the edge of the perimeter so you would just have to cut a notch across the width of a path to the soil. It all varies from house to house.

Up through the attic and down is the other option like already mentioned.

Or up with floor boards upstairs and run cable that way from above the MCB board to where you can get down to ground level close to the shed.

M cebee

Carlow52 wrote: »

Get a second meter in the meter box for garage

you'd have network charges and standing charges


if they fitted it


cost more that way

hesker

The MCB board is on the party wall (semi-d) so if going down I'd have to route out through front of house beside front door. Then I'd have to dig up the path all along the front of the house (about 25 ft) or a slice of the path anyway. Can't go straight out from front door to go around the length of the path as the drive way is concrete. Might save half the cutting that way but I'd prefer to avoid going out the front if possible.

The section of path underneath the meter box is going to be redone so that will be dug up anyway, hence it would be nice if I could route the cable out through there.

It would be really neat if I could pull the existing cable from the MCB to the meter cabinet out through the cabinet. Then I could drag 2 new cables with it and route the shed cable down the cavity at the meter. Just not sure how compliant that would be if it did work, as in if you have 2 cables in close proximity along much of their length is that a no no, or are they sufficiently shielded with the insulation they come with.

Bruthal

Having 2 cables run together is not a problem, but you wont realistically be able to pull one mains cable out and pull in 2 with it.

I would think the mains cable from the meter to the MCB board goes under the upstairs floor boards rather than into the attic anyway. But anything is possible. So up to attic or under upstairs flooring, or a combination of both seems the best route if you want to avoid surface job outside.

M cebee

across attic more than likely

down to consumer unit in pvc trunking or studwork

allow for length of cable run when sizing

hesker

Thanks for the help guys.

Time to do a bit of fishing.
Almost certain existing cable is routed through joists between floors and agree pull through of 2 cables would be tough. Attic route is likely to be the easier option.

Carlow52 wrote: »

You only need SWA when it is exposed outside, ordinary PVC PVC will do internally.

Does this mean I could run lighter cable internally and join to SWA using a junction box in the cavity.

Bruthal

hesker wrote: »

Thanks for the help guys.

Time to do a bit of fishing.
Almost certain existing cable is routed through joists between floors and agree pull through of 2 cables would be tough. Attic route is likely to be the easier option.




Does this mean I could run lighter cable internally and join to SWA using a junction box in the cavity.

The inner cable would need the same conductor size, but overall the cable would be lighter. A junction box would have to be accessible.

Going up to the attic should be possible. Are the walls dry lined upstairs? I usually cut out a single socket size square in one or 2 positions going up the wall for bringing cables into the attic, then battons of wood and screw the plaster squares back in and fill in the edges. Sometimes a cable can be fished up without doing this but for the size you will use, a hole cut near the ceiling will likely be needed as often there is a batton making any gap small. Need a boad lifted right above the MCB board to start usually.

Same at the ESB meter side, although i would keep any cable run out of that, but holes could be cut and replaced to assist the cable fishing down from attic to downstairs ground level. And a removal of skirting to drill out. Just suggestions, other ways might be apparrent in the house.

M cebee

i was looking at sketch and thinking of overhead to shed-duh;)

up to attic and back down is awkward enough

accross at joist level or underground all the way are more direct routes

if possible

hesker

Walls are dry-lined on the party wall. Reckon I should be able to figure out how to fish through the cable as I've done a bit of that before.

I was hoping to drop the cable down the cavity to the meter box and junction there by mounting a junction box on the chipboard. There's a nice free spot for it too.

robbie7730 wrote: »

Same at the ESB meter side, although i would keep any cable run out of that...

Why so Robbie? Would the ESB not look too kindly on me using the meter cabinet for that?

M cebee

the cabinet is for esbn equipment and consumer's main ocpd if fitted-so you'll have to avoid it

SWA is suitable for concealing in dry-lining if you can fish it all the way

you'll need a sparkie to size it and decide on best route anyhow

Bruthal

hesker wrote: »

Why so Robbie? Would the ESB not look too kindly on me using the meter cabinet for that?

I dont think they would, and i dont think they will like a cable coming in from the top of the meter box either even if they did allow you to have a cable into it.