Supply to garage.

[Edward67]

Hi ok here we go.
Friend has asked if can rewire his garage as he is turning it into a gym. I said ok no problem.

He the put the spanner in. Ok I want
1 circuit for a car charger. 7.4kw.
2 x 3kw heaters
1 x ring main for gym equipment. From what i can tell running machine is most power hungry.
1 x lighting circuit.

All on a 2.5mm incoming swa.

So now I need to split the meter tails.in the cupboard and put in 25mm swa cable. Run about 12 meters.

Pme 80amp.

So looking for thoughts.

He needs cutout upgrading to 100amp. Its large 5 bed already with a hot tub.

Do you think I should install 2 core swa and TT the garage.

Or 3 core swa to mini board in meter cupboard then to isolator.
Or a two core swa with separate earth cable run next to it. This is better as earth can be smaller diameter.

Due to the size of the earthing conductor with the mini boards even accept them.

Or thinking outside the box. I could run the swa and terminate to a metal bracket mounted in the meter cupboard then run into a double isolator switch which will protect the current house tails and new swa tails.
The issue with this is the tails from the bracket to isolator are not double insulated.
However they are In cupboard that requires a key to enter so does that comply. I'm not sure.

I already know about the debated exporting pme conversation so don't wish to revisit it please.

Looking for ideas or pictures of people who have performed this.
If it wasn't for a friend I would refuse because sometimes it's best to DGI.

All comments appreciated.

Pic.of meter cupboard attached. Mmmm loads of space? think there is room for mini board.

 

[pc1966]

Or thinking outside the box. I could run the swa and terminate to a metal bracket mounted in the meter cupboard then run into a double isolator switch which will protect the current house tails and new swa tails.

An isolator won't protect the cables, it should be a fused-switch. The DNO fuse should not be relied upon for protecting your cables, it is to protect the DNO network!

That takes most space of course...

Is the car charger a smart one that monitors total load to limit the draw if one or more feed is power-constrained?
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If the gym conversion has no extraneous aspects to it then PME derived CPC presents nothing special. What you may have to consider is cable protection, and if the end Zs is low enough to meet 5s disconnection on the feed.

 

[Edward67]

An isolator won't protect the cables, it should be a fused-switch. The DNO fuse should not be relied upon for protecting your cables, it is to protect the DNO network!

That takes most space of course...

Is the car charger a smart one that monitors total load to limit the draw if one or more feed is power-constrained?
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If the gym conversion has no extraneous aspects to it then PME derived CPC presents nothing special. What you may have to consider is cable protection, and if the end Zs is low enough to meet 5s disconnection on the feed.

Hi thanks for reply.
I don't fully understand your isolator point. The current tails are 15 hence they are on the isolator seen in the picture. They do not require fused switch? So why would my swa require one.

I see your point but not entirely sure I agree otherwise all meter tails would need one wouldn't they?

Hope you respond with your thoughts.

Thankyou.

 

[pc1966]

I don't fully understand your isolator point. The current tails are 15 hence they are on the isolator seen in the picture. They do not require fused switch? So why would my swa require one.

If they are longer than 3m they should be on a fused-switch based on 433.2.2 & 434.2.1

 

[Edward67]

If they are longer than 3m they should be on a fused-switch based on 433.2.2 & 434.2.1

So does the current meb one already installed in meter cupboard comply? Regs book at work but will read those regs in morning thankyou.

 

[buzzlightyear]

1 circuit for a car charger. 7.4kw.
2 x 3kw heaters
1 x ring main for gym equipment. From what i can tell running machine is most power hungry.
1 x lighting circuit.

All on a 2.5mm incoming swa.

So now I need to split the meter tails.in the cupboard and put in 25mm swa cable. Run about 12 meters.

Do you think I should install 2 core swa and TT the garage.

You being the spark then is down to you designing it, but has for the car charger then I would go for a zappi . So you do not need to be TT unless you have water or gas services in the garage.

 

[Edward67]

You being the spark then is down to you designing it, but has for the car charger then I would go for a zappi . So you do not need to be TT unless you have water or gas services in the garage.

My idea of TT was it means no need for three core swa. Therefore I don't end up with huge 25mm earth cable in meter cupboard.

 

[davesparks]

My idea of TT was it means no need for three core swa. Therefore I don't end up with huge 25mm earth cable in meter cupboard.

Can you expand on this please because it makes absolutely no sense at the moment.

Whatever you do at the load end of the cable it must have a CPC.
Are there any extraneous conductive parts in the garage? How far is the garage seperated from the house?

Why 25mm? That seems ridiculously oversized for the loads you have described.

What type of car charger is it and will it be used indoors or outdoors? Where does it stand with regards the special regulations for car chargers?
Don't forget there is ammendment 1 which deals with car chargers.

 

[Strima]

If he needs heaters in the gym he’s not training hard enough.

 

[Edward67]

Can you expand on this please because it makes absolutely no sense at the moment.

Whatever you do at the load end of the cable it must have a CPC.
Are there any extraneous conductive parts in the garage? How far is the garage seperated from the house?

Why 25mm? That seems ridiculously oversized for the loads you have described.

What type of car charger is it and will it be used indoors or outdoors? Where does it stand with regards the special regulations for car chargers?
Don't forget there is ammendment 1 which deals with car chargers.

Obviously it needs a cpc it will be a TT?
Car charger outside and all car chargers can go on TT but not all can go on a pme due to issues with breaks in neutral conductor potentially causing the car to become live.
No extraneous conductive parts but floor is concrete therefore my understanding is it will have to be TT.
So now I have answered my own question.
I will isolate with a double isolator in the meter cupboard run to mini board in meter cupboard. Run two core swa 16mm to garage. Terminate swa in meter cupboard and earth swa. In garage I will gland the swa so it is not earthed. Then I will put in rod and run new earth to my garage consumer unit which will consist of a Type A rcd because car charger will require it and the 4 mcbs job done.

 

[R-fur]

The DNO does not normally allow customers switch gear in the meter cupboard. Why do you need another isolator in there anyway? Block the tails at the consumer unit and fit a switch fuse there for your SWA.

 

[DPG]

Obviously it needs a cpc it will be a TT?
Car charger outside and all car chargers can go on TT but not all can go on a pme due to issues with breaks in neutral conductor potentially causing the car to become live.
No extraneous conductive parts but floor is concrete therefore my understanding is it will have to be TT.
So now I have answered my own question.
I will isolate with a double isolator in the meter cupboard run to mini board in meter cupboard. Run two core swa 16mm to garage. Terminate swa in meter cupboard and earth swa. In garage I will gland the swa so it is not earthed. Then I will put in rod and run new earth to my garage consumer unit which will consist of a Type A rcd because car charger will require it and the 4 mcbs job done.

Are you going to fit a fuse before the SWA?

Edit: I misunderstood. I see you are putting a separate consumer unit on the meter cupboard??

 

[radiohead]

Henley block the tails and install an IP metal fused switch disconnector under the meter box. Tails gland into the side and SWA straight into the bottom of the FSD.
You'll struggle to get a unit in the meter box and satisfactorily terminate the SWA, aside from the fact that the supply authority don't permit it.
If you want to TT the load end then break the armouring at the garage end but use the PME for earth fault protection for the cable.

 

[davesparks]

The DNO does not normally allow customers switch gear in the meter cupboard.

The bottom right quarter of a meter box is reserved for customers equipment.

The DNO do not own the meter box, the customer does.
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No extraneous conductive parts but floor is concrete therefore my understanding is it will have to be TT.

Nonsense, having a concrete floor does not require you to install a TT system.

What changed to make you choose 16mm now? That still sounds a bit big to my mind.

So how far is the garage seperate from the house?

 

[Edward67]

The bottom right quarter of a meter box is reserved for customers equipment.

The DNO do not own the meter box, the customer does.
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Nonsense, having a concrete floor does not require you to install a TT system.

What changed to make you choose 16mm now? That still sounds a bit big to my mind.

So how far is the garage seperate from the house?

15 meters about. I understand its large but as time goes by probably not large enough when.people have two electric cars. For few pounds seems better to be safe than sorry. I changed size because 25 will be a nightmare to terminate.