wiring to outside shed.

[mentalparametrics]

i was after a bit of advice.

iv recently bought a house and wish to put power into my new shed/workshop. i have purchased a garage consumer unit, 25M of SWA 2.5mm c/s area, 2 off - double plug sockets, 1 off - two way switch amd a floresent tube lighting (IP54).

Also i want to put an outside socket and a 2way switch against my wall of the house.

i have at present cable leaving the house going to an old outbuilding supplying power to it.

the question is.

can i use this cable to supply power to the above i wish to install or shall i have two seperate spurs in the kitchen. one for the power going to the shed with the consumer unit. the other spur for the outside switch and socket. or do i need to do something else.

many thanks

adam

 

[mapj1]

From what you describe the answer is 'perhaps' What is the rating of the cable you want to re-use,? is it on an RCD protected circuit?, do you know where it comes from ? and how much total load do you envisage using ?- 2.5mm will get you a 16A feed , but voltage droop (lights flicker in shed when applience plugged in) may be a problem, depending on the length.

More info needed I'm afraid. - oh, and have you searched (use the 'search' above) for other threads on supplies to sheds/garages etc - there is a lot of stuff here already from previous posters, you may find someone has already solved your problem, and if not at least you know what info togather to ask your question.

 

[mentalparametrics]

garage consumer box with a 63A RCD, along with a 16A and 6A MCB's. the existing wiring supplied to the old outhouse comes directly from a SECOND CU in the house. there are two fuses for this, why i dont know as there is only 2 CORE AND EARTH leaving the house to the outhouse.

length of SWA needed from house to shed will be 40 foot. i dont think there will be any voltage drop over this distance as the only appliance constantly being in use will be a fridge in the shed. the sockets are for consumables such as consumer worktop tools. and there the flouresent lighting.

have been looking thru searches as well . many thanks.

 

[mapj1]

OK, you will not need to have a 63A supply to your new CU, if you are just doing a 16A radial for power and the 6A breaker for one light fitting.
(40ft... 12m) yes voltage drop OK on 2.5mm at 20A load.
You will need to work out what those old fuses are feeding - it may be that one is just a spare, and to fit a 20A in the slot feeding the outbuilding. - make sure the existing wire is up to it - it too needs to be 2.5mm sq. or fatter. Please make sure that the armour of the SWA is properly clamped when you make it off - there is a lovely how not to do it thread
here
//www.diynot.com/forums/viewtopic.php?t=27081&highlight=swa go to the end for the pictures - he got it working eventually...
I must admit if you did not already have it I would have sugested 4mm SWA as it gives options interms of expansion later, but given your loading, I can't imagine any big problems, and a flickering light in a workshop is less nuiscence than the whole house.

I'm going to mention part P of the building regs, and point out that to be legal this sort of work is notifiable, and should be inspected by the local authority or their representative during installation, but personally I won't be terribly worried if you decide not to remember to notify the building control office and do it anyway, but do please be careful.

 

[mentalparametrics]

amny thanks mapj1. for your advice. will come in handy.

quote"
I'm going to mention part P of the building regs, and point out that to be legal this sort of work is notifiable, and should be inspected by the local authority or their representative during installation, but personally I won't be terribly worried if you decide not to remember to notify the building control office and do it anyway, but do please be careful.
"quote

i know what you mean. so much red tape. its all a money generating scam trying to make us all look like idiots.

cheers once again

 

[wileecoyote]

Excuse me for mentioning this.......but there is a lot of talk about voltage drops with smaller cables. Why is it that a 50m extension cable that is at most 2.5mm //www.diynot.com/shop/240V_50MTR_CABLE_REEL/4978 can deal with the basic requirements of a shed/garage load without any significant loss of voltage.
If all you require is a light and a couple of 13A sockets then is 2.5mm not enough even at 50m.
I know it saves digging the trench twice if you "overkill" in the 1st place but what about the guy that has no intention of ever installing a small factory at the bottom of his garden.

 

[pdcelec]

Extension leads are the responsibilty of the user and not the electrical installer. Therefore if a fire or other calamity occurs then it is your own fault for not doing the job correctly.

 

[wileecoyote]

Extension leads are the responsibilty of the user and not the electrical installer. Therefore if a fire or other calamity occurs then it is your own fault for not doing the job correctly.

I am assuming that the electrical installer has fitted the correct protection for a 2.5mm cable just as he would with a 4 or 6mm. The query I have is voltage drop of major significance?

 

[plugwash]

volt drop is somewhat less of an issue in reality than the regs make out mainly because realistic incoming mains voltage in most cases is FAR higher than the minimum allowed incoming mains voltage.

whilst we do advise people to stick to the 4% limit in the regs exceeding it is not a huge sin. Do consider disconnect times though especailly if using mcbs for protection (fuses gradually get slower as the current gets lower but if a MCB doesn't hit the fast trip point it immediately gets significantly slower).

 

[ban-all-sheds]

as the only appliance constantly being in use will be a fridge in the shed.

1) Will you have an alarm to notify you if the supply trips?

2) Have you checked that the fridge will work satisfactorily in the ambient temperatures you'll have in the shed in winter?

 

[plugwash]

i'm not sure if this is what bas meant but if you wan't a freezer down there though do not use a fridge-freezer unless you are sure it has two seperate thermostats. the same applies to the freezer compartment in a fridge.

 

[ban-all-sheds]

No - I meant that refrigeration devices have minimum ambient operating temperatures, below which they will not work. Probably varies by manufacturer, but 10°C is typical.

Many people have come unstuck by putting fridges and freezers in unheated locations.

 

[Steve]

i would have thought a fridge would work at any temperature, after all, refrigerant isnt in a great hurry to freeze up is it? I would have thought it would work less and less as the temperature dropped, towards winter, completely shutting off when the temperature is below 5 degrees, say.

What is it that stops a fridge from working below 10 degrees? A basic design flaw? Are freezers designed for lower temperatures? I might insulate my shed, so the freezer heats the space and has something to cool

 

[ban-all-sheds]

I've never looked into it in much detail, but I know it's a fact.

My guess is that when it's cold, the refrigerant cools too much during its voyage through the heat exchanger, and therefore when it passes through the expansion valve it doesn't boil, and therefore doesn't cool the interior.

But that might be complete b****cks.