Mains supply to Shed

K

kev78

hello again.
i have a question as regards supplying electricity to my shed. i will be using an electrician to do all the wiring up of consumer units etc but will do the running of cable myself.

The question is this
I currently have an external supply to the garage which has an RCD in the consumer unit at the house and a cable run through the loft then down the back wall across the garden wall to the garage into a seperate consumer unit with RCD'd socket ring and lighting cct.
The cable runs through some heavy duty outdoor trunking.
Will the electrician be legally able to split the supply cable on its way to the garage and then run a small consumer unit for the shed or will a seperate feed from the house/garage consumer units to the shed be needed?

Just wanting to guesstimate the size of the job before i get someone round to have a look
 
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Will the electrician be legally able to split the supply cable on its way to the garage and then run a small consumer unit for the shed or will a seperate feed from the house/garage consumer units to the shed be needed?
Depends. Is the current setup installed properly? Is there enough capacity to supply this extra CU?

Can you post a few pics of your supply? It may be better to ring round a few sparks and see what they say you require which will give you a better idea. Difficult to suggest much without being able to see the existing setup. :LOL:
 
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K

kev78

ok bongos thanks

so is it conceivable that providing the cable size and the loading works out that a spur could be taken from the feed to the garage and theis would comply with the regs?
 
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sorry kev perhaps I was a little vague.

Usually when a DIYer comes here saying something runs in "heavy duty conduit" it turns out being plastic trunking or hosepipe. ;)
 
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so is it conceivable that providing the cable size and the loading works out that a spur could be taken from the feed to the garage and theis would comply with the regs?
Bit confused. You mean you want to supply the shed from the garage, yes? It certainly is concievable. It would be better than "splitting the supply cable on the way to the garage" as you ask in your first post.

But a few questions from me...:LOL:

What size MCB is the supply cable on in the house?

Is it actually protected by the RCD on the house CU or in an unprotected way?

What size/type of cable is it? Is the trunking plastic or metal?

How long is the run to the garage on the existing setup?

And what sort of power are you requiring in the shed and garage? Just a couple of sockets and a light or welding equipment etc...?

This obviously makes a difference in what kind of supply you need to install and what a spark can do to add to your existing setup. ;)
 
K

kev78

Conduit is definately plastic.
I'll have a good look tomorrow and answer your questions bongos.
The loads are going to be a washer and dryer in the shed and a freezer and a few lights in the garage, plus the occasional power tool usage

Was really hoping to be able to chop the supply to the garage and using a junction box or other suitable outdoor device split the supply as this would save about 20 metres of wiring.

I am wanting the most cost effective way that complies with the regs thats all. As i said i'm not planning a bodge job just the easiest and best solution using a qualified spark.
 
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i will be using an electrician to do all the wiring up of consumer units etc but will do the running of cable myself.
Will you be expecting an EIC and Building Regulations compliance certification from the electrician?


Just wanting to guesstimate the size of the job before i get someone round to have a look
If so then you need to stop asking here about what might or might not be done, and get people round to have a look asap, because the electrician you choose is the only person who can make all the decisions you're asking about, and any work that you do, e.g. digging trenches, must be under his direct guidance and supervision.

Nothing else will allow him to certify that he did all the work, so if you do want all of this to be legal then forging ahead hoping to get someone in to connect it up and certify will only lead to a serious disappointment for you, and a lack of paperwork.
 
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Was really hoping to be able to chop the supply to the garage and using a junction box or other suitable outdoor device split the supply as this would save about 20 metres of wiring.
It might be possible. Depends on what you currently have.

By the way, plastic conduit is not "heavy duty outdoor conduit" and is not sufficient protection for Twin and earth outdoors.

"Heavy duty outdoor conduit" would be defined as earthed galvanised steel conduit. Much more appropriate, but a better solution would be armoured cable, cheaper too. ;)
 
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Conduit is definately plastic.
So quite possibly inappropriate.

Or too small for the cable you have or will need.

Don't be surprised if your electrician says it all has to be replaced with armoured cable.


Is the shed insulated and heated?


Was really hoping to be able to chop the supply to the garage and using a junction box or other suitable outdoor device split the supply as this would save about 20 metres of wiring.
You cannot possibly do anything like that and spring it on an electrician.

And you should never compromise on the right design just to save a few quid's worth of cable.


As i said i'm not planning a bodge job
I'm afraid that's not how it's looking....
 
K

kev78

i will be using an electrician to do all the wiring up of consumer units etc but will do the running of cable myself.
Will you be expecting an EIC and Building Regulations compliance certification from the electrician?


Just wanting to guesstimate the size of the job before i get someone round to have a look
If so then you need to stop asking here about what might or might not be done, and get people round to have a look asap, because the electrician you choose is the only person who can make all the decisions you're asking about, and any work that you do, e.g. digging trenches, must be under his direct guidance and supervision.

Nothing else will allow him to certify that he did all the work, so if you do want all of this to be legal then forging ahead hoping to get someone in to connect it up and certify will only lead to a serious disappointment for you, and a lack of paperwork.


Like i said just wanted an idea - i will be getting an electrician in before doing any work - nice to have more than one opinion before getting in the experts in. But i am starting to think this may be a mine field and best just get an electrician round once the shed is in position.
The main thing i wanted to know is would it be conceiveable that the supply to the garage could be split or is it a definate no no
 
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To split the cable, you'd ideally need to have two fuses or breakers at the split to protect both runs seperately. Of course, since you will need to change the entire cable anyway, this shouldnt be a problem.
 
K

kev78

Conduit is definately plastic.
So quite possibly inappropriate.

Or too small for the cable you have or will need.

Don't be surprised if your electrician says it all has to be replaced with armoured cable.


Is the shed insulated and heated?


omg will you please read or just stop replying. i will not be doing any work without an expert opinion - i am not going to spring anything on anyone and the freezer is in the garage and has been for 2 years since the qualified electrician installed the cable run from the house to the garage and certificated it

Was really hoping to be able to chop the supply to the garage and using a junction box or other suitable outdoor device split the supply as this would save about 20 metres of wiring.
You cannot possibly do anything like that and spring it on an electrician.

And you should never compromise on the right design just to save a few quid's worth of cable.


As i said i'm not planning a bodge job
I'm afraid that's not how it's looking....
 
K

kev78

Conduit is definately plastic.
So quite possibly inappropriate.

Or too small for the cable you have or will need.

Don't be surprised if your electrician says it all has to be replaced with armoured cable.


Is the shed insulated and heated?

Will be getting my money back from the qualified spark who certificated the mains install to the garage then
omg will you please read or just stop replying. i will not be doing any work without an expert opinion - i am not going to spring anything on anyone and the freezer is in the garage and has been for 2 years since the qualified electrician installed the cable run from the house to the garage and certificated it

Was really hoping to be able to chop the supply to the garage and using a junction box or other suitable outdoor device split the supply as this would save about 20 metres of wiring.
You cannot possibly do anything like that and spring it on an electrician.

And you should never compromise on the right design just to save a few quid's worth of cable.


As i said i'm not planning a bodge job
I'm afraid that's not how it's looking....
 

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