Easiest way...

[SSE]

Asked to have a look at a job at an old old house (never good). Anyway all the guy wants is power in his shed in the back garden for three double sockets and one strip light (about 3/4 metres from the house). Only problem being theres no way of getting to the consumer unit as it's at the far away end of the house and all floors are laminate flooring so can't be lifted and theres no underfloor access. The closest power to the shed is part of the ring that's in the extension and outwith this theres no other access to the house as the walls are literally a metre thick or more thick and even getting through the walls wouldn't help as laminate flooring everywhere.The extension was wired before the laminate flooring was put down, all from below. Just wondering what the best way to go about this would be. I always have just run a 6mm supply to sheds, never tapped into circuits and infact don't even know if your allowed to, I always thought a shed would have to be on it's on circuits to comply with regulations.

 

[GLENNSPARK]

cant you run an armoured on the outside of the house (clipped direct) ? We`v had to do this before. If you cant bury the thing then run it up the side of the house to a catenary wire and thus to the shed.......

 

[SSE]

Cheers for your reply. It's not a problem getting it from the extension to the shed, dig a trench no bother. It's the getting it from inside the extension to the opposite side of the house. I'd imagine the shed has to have it's on point of isolation and am not keen on splitting the ring in the extension and including the shed (as has been suggested by another sparky I know) Can't run it round the house as it's joined on to houses either side...

 

[telectrix]

you could come off the ring final. fuse down by means of a FCU (RCD type if not already an RCD protecting the ring).then 2.5T/E to adaptable box outside, then SWA to shed. this would limit him to 13A in the shed of course., unless you fused down to 20Awith a MCB in an enclosure to give a bit more. although not the ideal way of doing it, it would comply. a light could be added in the shed by means of a 3A or 5A FCU in the shed. i assume there are no extraneous conductive elements in the shed.

 

[Silly Sausage]

Can't run it round the house as it's joined on to houses either side...

Could you run SWA up the outside of the front of the house, into the roof space then down the back wall into the garden?

 

[GLENNSPARK]

you could come off the ring final. fuse down by means of a FCU (RCD type if not already an RCD protecting the ring).then 2.5T/E to adaptable box outside, then SWA to shed. this would limit him to 13A in the shed of course., unless you fused down to 20Awith a MCB in an enclosure to give a bit more. although not the ideal way of doing it, it would comply. a light could be added in the shed by means of a 3A or 5A FCU in the shed. i assume there are no extraneous conductive elements in the shed.

I thought about this tel, but, as you say your limited as to the max. current suply (13A) or, as you say, the 20A breaker in enclosure...........but its still going to limit what he uses in that shed....mind you depends on how big the shed is doesn`t it...i mean,....its hardly going to be a factory is it..lol...

 

[SSE]

you could come off the ring final. fuse down by means of a FCU (RCD type if not already an RCD protecting the ring).then 2.5T/E to adaptable box outside, then SWA to shed. this would limit him to 13A in the shed of course., unless you fused down to 20Awith a MCB in an enclosure to give a bit more. although not the ideal way of doing it, it would comply. a light could be added in the shed by means of a 3A or 5A FCU in the shed. i assume there are no extraneous conductive elements in the shed.

So just spur off the socket to the enclosure with the 20A mcb then from the enclosure to the adaptable box outside then to the shed? Lookin' like it's going to be the best bet...

Could you run SWA up the outside of the front of the house, into the roof space then down the back wall into the garden?

He wasn't keen when I suggested this.

 

[telectrix]

another way would be to split the ring, 2 x 2.5mm to ad. box, then 4core SWA to garage, using the armour as cpc. that way he'd have an extended ring. provided that the additional load is not too much for the ring's MCB, and of course, RCD must be already installed or added.

 

[telectrix]

So just spur off the socket to the enclosure with the 20A mcb then from the enclosure to the adaptable box outside then to the shed? Lookin' like it's going to be the best bet...

it's certainly the cheapest option. remember the RCD and to earth 1 end of the armour ( assuming 3 core SWA ). if 16A is enough for the shed load, you could fit a 16A MCB. either way, as long as the cable you install is protected from a load greater than its rated CCC, job's a good 'un.

 

[SSE]

Thanks very much for theses suggestions telectrix, very much appreciated I'll have a wee think about it over the next day or so.

 

[GLENNSPARK]

Whats the main earthing arrangements here?........

 

[telectrix]

and if there is an RCD already installed, check it's rated trip current. if it's >30mA then you'll have to address that issue as well. if necessary, fit one with your MCB at the point of spurring off.

 

[telectrix]

Whats the main earthing arrangements here?........

good point. the earthing and bonding needs checking and bringing up to current standards if not already compliant.

 

[SSE]

Whats the main earthing arrangements here?........

It's a TNCS system. 16mm earth.

and if there is an RCD already installed, check it's rated trip current. if it's >30mA then you'll have to address that issue as well. if necessary, fit one with your MCB at the point of spurring off.

New consumer unit been fitted so RCD is 30mA.

good point. the earthing and bonding needs checking and bringing up to current standards if not already compliant.

I upgraded the earth to 16mm when I installed the new consumer unit today. The main water bond is a 6mm and can not due to access be upgraded to a 10mm until he lifts all the laminate flooring up, which he is going to be doing in 6 months time so it will be upgraded then. I've noted this on my test sheet so as far as I'm aware that's my end covered.

 

[GLENNSPARK]

Could you not use the 6mm as a draw wire?...use that to pull a 10mm in? As tel asked earlier in this thread are there any extranious conductive parts within that shed?....an outside tap maybe?.........

 

[SSE]

Could you not use the 6mm as a draw wire?...use that to pull a 10mm in? As tel asked earlier in this thread are there any extranious conductive parts within that shed?....an outside tap maybe?.........

No it's not a straight forward run to be able to use as a draw wire, it just wouldn't pull. I just put it down on my test sheet that it didn't comply and correct me if I'm wrong but I'm pretty sure that's my end covered? As soon as the floor is lifted it'll be upgraded to a 10mm.

Sorry I forgot to reply regarding the extranious conductive parts. No there are none that I can think of off the top of my head. The outside tap is on the house wall.

 

[GLENNSPARK]

Well thats better for you as you would have had to extend the equepotential zone from the house to the shed in 10mm as its a TN-C-S earthing arrangement.
As far as the 6mm bonding is concerned i was under the impression that it had to comply with the current edition of BS 7671 before undertaking any more work. But others may post thats wrong in which case i will happily stand corrected.

 

[SSE]

Well thats better for you as you would have had to extend the equepotential zone from the house to the shed in 10mm as its a TN-C-S earthing arrangement.
As far as the 6mm bonding is concerned i was under the impression that it had to comply with the current edition of BS 7671 before undertaking any more work. But others may post thats wrong in which case i will happily stand corrected.

Mmm, I've never heard this but certainly ain't doubtin' it's true. Could well do with finding out though as I'm meant to be doing it tomorrow!!

 

[GLENNSPARK]

check out tel`s post (13) mate.....

 

[SSE]

check out tel`s post (13) mate.....

Ah never noticed that post. Looks like I'll maybe have to put this one hold then until he lifts the flooring so as that I can upgrade the earth to 10mm.

Also, to what extent does this go? ie are you saying if theres still a 6mm then no electrical work at all can take place in the house?

 

[Octopus]

Ah never noticed that post. Looks like I'll maybe have to put this one hold then until he lifts the flooring so as that I can upgrade the earth to 10mm.

Also, to what extent does this go? ie are you saying if theres still a 6mm then no electrical work at all can take place in the house?

BRB 131.8 is worth a read in such situations, then its up to you to determine what's necessary.

10mm is mandatory for rewires/new installs

 

[telectrix]

apply the adiabatic to the main earthing conductor. if the answer is 12mm or less, then the 6mm can stay as long as it's intact and shows no sign of deterioration, until it can be replaced. ( note in comments on cert.)

 

[ezzzekiel]

Agree if readings are ok and no signs of damage then no reason why it cant be left just note it on cert

 

[SSE]

Went to job today and explained everything to the guy and after a while he decided to lift the flooring that I needed as it's gonna be coming up soon enough anyway. When he lifted it though he had to cut a track in the flooring under neath and he ended up sawing a pipe in half with the electric saw!! Water evrywhere!! Managed to get a clear enough run and just put a 6mm supply in for the shed and upgraded the earth to 10mm. Thanks for everybodies input though, picked up a couple of things I never knew anyway! Still learning every day! ha

 

[Knobhead]

Could you run SWA up the outside of the front of the house, into the roof space then down the back wall into the garden?

Another way around this.

If it’s an old house in a terrace I would be surprised if it doesn’t have a cellar. Get yer sen down't cole ole lad!