Workshop power

[Confused but learning]

Hello can anyone offer and advice on running power to an workshop. All work will be done by a professional electrician, I am merely seeing if my idea is feasible. So far I have 6mm swa prysmian cable buried according to reg, sand bedded and warning tape over etc 6.5 metre run.
I have recently had a new electric oven installed which is 240v 2075w. I have an unused switched supply on the kitchen ring main for an old baseboard heater.
Would the following be possible, connect the over to the unused 13amp switch, use the oven supply which is a 32amp supply with a dedicated rcd in the main panel to power the workshop?
The total distance for the shed including the existing cooker feed is 16 meters.
I am planning to run the trunking for the internal cable when I rip out the kitchen.
As I said I will not be doing any of the electrical work and will get a professional electrician to do it but wanted to know if the concept will work or if I am missing something obvious.

 

[DefyG]

Do you a electric hob? does it have its own 32A circuit ? if so, could the oven be connected to that circuit somehow as loads over 2kw (2000w) should be on a dedicated circuit.

 

[Confused but learning]

Do you a electric hob? does it have its own 32A circuit ? if so, could the oven be connected to that circuit somehow as loads over 2kw (2000w) should be on a dedicated circuit.

Sorry I should have said I have a gas hob that only has an electrical feed for the ignition

 

[Confused but learning]

Sorry I should have said I have a gas hob that only has an electrical feed for the ignition

But if anything 2000w plus needs a dedicated supply I guess the idea is not a good one.

 

[brianmoooore]

Ideally you would run the SWA all the way from the garage to where your consumer unit is, and connect the SWA to a non RCD breaker, or preferably to a separate switch/fuse.
Always intrigues me why DIYers and some professionals always use the minimum amount of SWA necessary, and then join to T&E.

 

[Confused but learning]

Ideally you would run the SWA all the way from the garage to where your consumer unit is, and connect the SWA to a non RCD breaker, or preferably to a separate switch/fuse.
Always intrigues me why DIYers and some professionals always use the minimum amount of SWA necessary, and then join to T&E.

Thanks, as I said I don't know so I thought I'd ask some people who do. Running to the consumer unit is going to be a huge mess so I guess this will have to wait for a while.

 

[DefyG]

What is the loading (expected) for the workshop ....... it may be that the workshop connected to the 13A S/FCU might work?

 

[Confused but learning]

What is the loading (expected) for the workshop ....... it may be that the workshop connected to the 13A S/FCU might work?

I will be running various power tools including, a table saw, vacuum for extraction etc. Possible heat in the winter so I was thinking I'd need a full 30amp supply. Light will be led all the other power tools are less than 2000w but cumulatively it all adds up.

 

[brianmoooore]

What is the loading (expected) for the workshop ....... it may be that the workshop connected to the 13A S/FCU might work?

This is true for a light plus occasionally used 13A socket in a shed, but for a workshop as above it's really a non starter. Apart from the extremely limited load, the RCD and type 2 MCB in the house will be a pain to reset.
For that lot, I'd up the cable to 10mm2 SWA and 45A switch fuse.

 

[Confused but learning]

This is true for a light plus occasionally used 13A socket in a shed, but for a workshop as above it's really a non starter. Apart from the extremely limited load, the RCD in the house will be a pain to reset.

Was planning to put a separate small consumer unit in the shed, but even so I think a separate feed is probably the only way to go. Just have to explain to the Mrs why I am knocking out the under stair area ?

 

[brianmoooore]

CU with RCD or RCBOs in the workshop is the way to go, but there's no point fitting an RCD there if the power passes through another one in the house. That's a reason to use SWA all the way, so that the cable doesn't need RCD protection.

 

[pc1966]

Is there any other route for the cable, even if it is run around the outside of the house?

Whatever you do, you might also think about having emergency lighting so if the power goes off for any reason you are not plunged in to total darkness with sharp tools around, etc. You get LED strip lamps with that built-in, so if you have at least one emergency LED baton out of 2-3 for the working light you would be a lot safer.

 

[Pete999]

Do you a electric hob? does it have its own 32A circuit ? if so, could the oven be connected to that circuit somehow as loads over 2kw (2000w) should be on a dedicated circuit.

Do you have a regulation number DefyG I always thought it was just an advisory notification

 

[loz2754]

Do you have a regulation number DefyG I always thought it was just an advisory notification

It's only mentioned in appendix 15 (informative) as far as I'm aware.
But probably a good idea to comply with it anyway, as the ring may already be somewhat fully loaded.

 

[Pete999]

It's only mentioned in appendix 15 (informative) as far as I'm aware.
But probably a good idea to comply with it anyway, as the ring may already be somewhat fully loaded.

I agree why won't/don't the IET make it a regulation , make life easier for all concerned, don't you think?

 

[brianmoooore]

I agree why won't/don't the IET make it a regulation , make life easier for all concerned, don't you think?

Because we're supposed to be 'competent persons' who should be capable of designing a circuit outside of the norms. In most cases, a 2kW+ fixed load shouldn't be connected to a RFC, but occasionally (e.g. very short duration load?) it may be acceptable.

 

[Pete999]

Because we're supposed to be 'competent persons' who should be capable of designing a circuit outside of the norms. In most cases, a 2kW+ fixed load shouldn't be connected to a RFC, but occasionally (e.g. very short duration load?) it may be acceptable.

Agree but many Electricians want the rules and regulations in black and white, it wouldn't be to much to ask to point this out to the less educated newbies amongst our community would it?, maybe those that think they know it all will disagree. What do you think? I'm not including you in the know it all statement by the way.

 

[pc1966]

I agree why won't/don't the IET make it a regulation , make life easier for all concerned, don't you think?

I guess the obvious answer is that it is not always a problem.

Usually rules & regulations always get bigger with time as the authors try and deal with each "WTF?" that an inquiry reveals, but as they become more prescriptive you end up with dumb things being done to follow the letter of the regulation, but without any understanding of why it might be needed (or not) and possibly causing other problems or risks.

 

[Mourad]

Hello can anyone offer and advice on running power to an workshop. All work will be done by a professional electrician, I am merely seeing if my idea is feasible. So far I have 6mm swa prysmian cable buried according to reg, sand bedded and warning tape over etc 6.5 metre run.
I have recently had a new electric oven installed which is 240v 2075w. I have an unused switched supply on the kitchen ring main for an old baseboard heater.
Would the following be possible, connect the over to the unused 13amp switch, use the oven supply which is a 32amp supply with a dedicated rcd in the main panel to power the workshop?
The total distance for the shed including the existing cooker feed is 16 meters.
I am planning to run the trunking for the internal cable when I rip out the kitchen.
As I said I will not be doing any of the electrical work and will get a professional electrician to do it but wanted to know if the concept will work or if I am missing something obvious.

Hi,
Yes you can do it and I think that it's you who is a professional electrician, all what you've to do is to divide 2075w per 230v, you will find less than 10 ampers and it's exactly a value near breaker rating, 13 ampers, in the other hand, you have to set up an rcd upstream the breaker.

 

[Soi disant]

Do you a electric hob? does it have its own 32A circuit ? if so, could the oven be connected to that circuit somehow as loads over 2kw (2000w) should be on a dedicated circuit.

Do you have a regulation number DefyG I always thought it was just an advisory notification

But in any event if you use the correct value of U0 it is less than 2kW.