Running electrics to outbuilding.

[matt204]

Hello all, I am very new to electrics and am getting an electrician to do required work. However, I thought I would just check to see if it correct or if it just a cheap and easy option.

I have just built a new kitchen extension and the electrics have been installed by adding another ring main ( I think) from the existing kitchen. Is this an acceptable method?

For the external power supply to workshop the electrician has come off one of the sockets directly outside. Is this OK?

I am just about to bury the cable under the patio I am laying and need to know what cable to run up to the workshop. Does it need to be armoured? How shall I go about connecting the existing cable to the armoured cable?

Many thanks.

 

[ericmark]

As to outbuilding See Electrical installations outdoors: a supply to a detached outbuildingYes you need armoured and you will need some sort of box to gland the armoured into there are other options but box is easy option.

 

[Chri5]

I have just built a new kitchen extension and the electrics have been installed by adding another ring main ( I think) from the existing kitchen. Is this an acceptable method?

He will have added to the existing ring, rather than provided a new circuit- check at the fuse board, do you now have 2 x fuses for the kitchen area, or just the one ?

For the external power supply to workshop the electrician has come off one of the sockets directly outside. Is this OK?

It's okay, but limits the max load to 13 amp. Since the kitchen tends to be the highest loaded circuit in the house you or he should have assessed the load requirements of the kitchen and the outbuilding to see if the circuit combined with the spur to the outside is suitable.

I am just about to bury the cable under the patio I am laying and need to know what cable to run up to the workshop. Does it need to be armoured? How shall I go about connecting the existing cable to the armoured cable?

Many thanks.

1st of all the external work needs to be notified under Part P, this is normally done by the electrician.

Whilst you may be keen to save funds, doing it part DIY and part sparks for termination, testing, cert and notify it may well end up being more expensive.

You best bet is to find an electrician, ask him to design, size and supply the cable.
You agree the cable route to regulations, you run it in (saving paying him to do it) and he returns to finish off the cable termination etc

You haven't mentioned the distance for the cable run, or if the kitchen is RCD protected (required) or what you intend to put on the cable at the outbuilding (Lights, sockets, appliances, heating, workshop and power tools) etc

 

[matt204]

Thanks for the replies.

The run for the cable is aprox. 25m to the shed. In terms of uses, I will be having 2 lights and about 3 double sockets for using power tools and a heater a fridge and a freezer. Is this quite a lot for a shed?

I have no idea as to whether the kitchen is RCD protected.

I think I am getting confused.

 

[Chri5]

I think I am getting confused.

Sorry

Outside electrics and electrical sockets that could be used via an extension lead outside MUST be RCD protected.

Part P is a requirement for outside work and is notified to the Council.

(if you don't - when selling there will be issues, if you have a claim on the insurance there could be issues if it brings in to play any of the work you did)

The run for the cable is aprox. 25m to the shed. In terms of uses, I will be having 2 lights and about 3 double sockets for using power tools and a heater a fridge and a freezer. Is this quite a lot for a shed?

The absoute mas load is restricted to 13 ampx x 230v = about 3000w

So tally up the use in the shed

Lights 2 x 60w = 120w
Fridge ? 200w ?
Freezer ? 200w ?
Power tools (you only use 1 at a time) say 750w
Heater ?

The heater could be the issue, the fridge / freezer is a blind guess.

Per my calcs 2.5mm core SWA will support just over 3kw / 3000w

 

[ericmark]

I think you may have a problem 25 meters is a long run. The electrician should have left you with an installation certificate which will tell you the earth loop impedance at the socket this can be converted into volt drop and then we can see how much is left to play with.

But to run what you say on 13A seems to be sailing close to the wind and to get more than 13A most likely the cable will need to come from the consumer unit.

I would think you are looking at around 16 to 20 amp which could be done with 2.5mm but only just so I would get the electrician who is running the job to select the cable for you.

He will measure everything first and calculate what can do the job. With that length you may need thicker cable.