Power to Shed

JOHNPT

I have a got a few enquiries about putting more to an outside shed.

1 Is it ok to take a spur off a radial circuit from say the kitchen and drill through wall and use 2.5 SWA to feed a supply to shed?
2 Under what circumstances do u have to have a seperate fuse board in outside shed. If for example u are just having one double socket and one light which u use a fused spur to fuse it down do u need a seperate fuse board in shed?
3 Wats the max load that u can use from a spir taken off kitchen to shed. Say someone wants a washing machine and dryer which may potentially overload the supply and u explain to the customer that this may be the case but they dont want to go to expense of bringing a seperate supply from fuseboard is it ok to go ahead as long as they agree and understand it may cause fuse to trip because of an overload??
4 If it is an outside shed can the wiring be done in normal T&E or do u have to use MYMJ?
5 Does all fittings have to be waterproof or is it up to your own discretion
6 If u decide to bring a seperate supply from the fuse board using 6sq T&E but there is no existing ELCB or earth rod in the house do u have to put one in the main board? What about if the customer says they dont want to go to enpense of doin this are you covered if u have explained to them.
7 What size main fuse should be used in the sub-board in the outside shed if it is 6sq supplying it. Some wholesalers always supply 50 amp main fuse for sub board surely that is too high a rating.
8 Do u need an earth rod for outside shed if there is none in main board


Thanks in advance

davelerave

1.yes but not for a washer and dryer
2.if you're bringing a cable from main board fit a fusebox .if you have to take power off a socket use a spur for the lightswitch
3.dont do it
4.use nym if possible
5 i usually fit ip rated lights and switches anyway i dont know what the reg are for this
6.you can put an earthrod at the main board not at the shed .use an rcbo for your work if possible that way your work is seperate from the house wiring
7 i usually fit a 32amp mcb at the house and a main switch at the shed fuse board
8 no. fit a rod at house. only one rod per domestic installation

JOHNPT

Re Q 7 Wat size main switch fuse would u use in the sub board

Nuravictus

JOHNPT wrote: »

Re Q 7 Wat size main switch fuse would u use in the sub board

Thats what the 32Amp MCB is for. I dont think you need a Main Swicth Fuse as the installation is still part of the main installation since your supply from the board will be protected by the 63Amp Main Switch Fuse already. Everything in a Installation must be killible by the 63Amp Main Fuse so anything you install will come after that so therefore will be protected by it.

JOHNPT

The 32 amp MCB is at the main fuse board to protect the cable going to the shed. But what size neozed fuse do u use in the sub board?

davelerave

Those neozed fuses are easily upped to 63amp by the customer later afaik.thats a problem

Dotsie~tmp

A NeoZed switch-fuse is only really essential if you are feeding the sub board from the load side of the meter or feed side of the main fuse board's switch-fuse. In which case its supposed to be fed in 16sq ! (or maybe 10 minimum i cant remember).

Anyway no need to do that. Either of the following will do.

- If the load is under 20A, feed the shed from the main board in 2.5 (SWA if burried, NYMJ if clipped on a wall). The NYM/SWA should come from a 20A MCB at the main board on the RCD. You can go into a small enclosure with a 10 and 20 amp MCB for the 2 circuits. If you don't want to put a small enclosure in the shed the light must be switched by a sw/fuse spur fused to 3 amps. All wiring in shed is 2.5 except the load out of sw/fuse spur to light which is 1.5.

- If the load is under 30A, feed the shed from the main board in 6sq (SWA if burried, NYMJ no use i dont thik its stranded at 6sq). The SWA should come from a 32A MCB at the main board on the RCD. You should go into a small enclosure with a 10 and 20 amp MCB for the 2 circuits.

- If the load is under 13A, feed the shed from a spur off a radial socket circuit. Run NYMJ or SWA as needed. Again you can go into a small enclosure with a 10 and 20 amp MCB for the 2 circuits. If you don't want to put a small enclosure in the shed the light must be switched by a sw/fuse spur fused to 3 amps. All wiring in shed is 2.5 except the load out of sw/fuse spur to light which is 1.5.

If you did have the time and money for propper sub boad with 16sq it would essetially be the same board as the main one (MCBs, RCD etc) except no earth-rod.

davelerave

You shouldnt ever take a supply from the feed side of the consumers main switch fuse even in 16 sq

JOHNPT

Thanks for all the replies I understand it all except one thing. If take a feed from the main board in 6sq SWA and u put a 32 amp MCB on main board to protect this thats all correct. However when u bring the 6 sq into shed and u doin up a sub board do u not need a main fuse in the sub board before u connect into your 2 MCBs to feed your two circuits. So what size main fuse do u use in sub board??

davelerave

In the shed Fit a main switch an rcbo for the socket and a lighting mcb dont connect to the rcd in the house if there is one .(the light and socket would trip together and your work gets tied up with the house wiring if the rcd starts tripping later)i think those 35/50/63amp neozed fuses are all interchangeable i wouldnt bother using them for 6sq anyway if thats the type youre talking about

Dotsie~tmp

There is no need for another high rupture capacity SW/Fuse if you take supply off a 32A MCB covered by the RCD. Also no need for RCBO as it will be covered by the RCD. Keep it simple.

JOHNPT

Ok so u can go straight into the 20 amp and 10 amp MCB in the sub board and thats all u need in sub board?
The wholesaler I went too said there should also be a main switch fuse in sub board protected by a 50 amp neozed fuse so if i wanted to isolate the power in the shed I could just knock down the main fuse.
So this is incorrect info?

davelerave

JOHNPT wrote: »

Ok so u can go straight into the 20 amp and 10 amp MCB in the sub board and thats all u need in sub board?
The wholesaler I went too said there should also be a main switch fuse in sub board protected by a 50 amp neozed fuse so if i wanted to isolate the power in the shed I could just knock down the main fuse.
So this is incorrect info?

Ya a switch or switch fuse(the fuse isnt important its a main switch) in the shed .put the 32amp mcb at the house.

davelerave

Dotsie~tmp wrote: »

There is no need for another high rupture capacity SW/Fuse if you take supply off a 32A MCB covered by the RCD. Also no need for RCBO as it will be covered by the RCD. Keep it simple.

Theres 5 minutes work and a tenner in the difference any good sparkie will use his own rcbo for the shed socket.

JOHNPT

Thanks

Dotsie~tmp

davelerave wrote: »

Theres 5 minutes work and a tenner in the difference any good sparkie will use his own rcbo for the shed socket.

Any good sparkie wouldn't use an RCBO that cost a tenner. Plus a slightly bigger enclosure = my doubting your costing/time. Anyway why all this talk about a sub board! Your just supplying a shed with a few sockets and a light. All you want is a basic extra final circuit. Just get the load right and thats it. I presume youre doing this for yourself cos a spark wouldnt be inventing unnecessary expense.

JOHNPT

I dont mind a little extra expense if it is done right. Is it not laid down in the rules or is it not good practice that if your feeding a shed u have to have a sub board in it.

davelerave

Dotsie~tmp wrote: »

Any good sparkie wouldn't use an RCBO that cost a tenner. Plus a slightly bigger enclosure = my doubting your costing/time. Anyway why all this talk about a sub board! Your just supplying a shed with a few sockets and a light. All you want is a basic extra final circuit. Just get the load right and thats it. I presume youre doing this for yourself cos a spark wouldnt be inventing unnecessary expense.

i advised him to fit a sub-board with a main switch rcbo and a lighting mcb if he's using a 6sq supply.you think he should connect it into the rcd at the house and fit a 10a and 20amp mcb outside .hardly surprising anyway since you seem to think its ok to connect subboards to the feed side of the consumers main switch fuse

JOHNPT

I am agreeing with you Dave it was that other person i didnt agree with. Thanks for your help it was very precise and no short cuts. Thanks again

Stoner

http://www.boards.ie/vbulletin/showthread.php?t=2055400462

there is a diagram of a small consumer unit in this thread that would be suitable for a shed, it might be of some use to you.

davelerave

For a washer and dryer in the shed use 2 seperate sockets .fit an rcd and 2 mcbs for these and your main switch and lighting mcb .a single 20amp rcbo is likely to overload

Stoner

davelerave wrote: »

For a washer and dryer in the shed use 2 seperate sockets .fit an rcd and 2 mcbs for these and your main switch and lighting mcb .a single 20amp rcbo is likely to overload

I've used this arrangement for exactly this requirement many times, my own place included and I have never had an overload issue, but following davelerave's instructions above will do no harm and would future proof the arrangement.

In many houses one radial circuit takes care of the washing machine and the dryer while another deals with freezer, fridge, micro, toaster, kettle etc. It may all depend on what else you end up with out in the shed, like an additional freezer or work tools, if you think you will have other requirements adjust your switchgear to suit.

JOHNPT

Thanks for all detailed replies