UK Consumer Unit spare way

[justeez81]

Hi all. I am due to get an EV wallbox fitted so I will be running a new 6mm SWA from under my stairs to the termination point outside. My issue is I have no spare ways for a 32A breaker in my consumer unit for the installer. Is there any recommendations on shifting some load to free up a way for a new mccb?

Consumer layout

Main Switch/RCD/16A cooker/32A upstairs sockets/32A kitchen +outdoor sockets/10A boiler +loft/6A downstairs lights/RCD/6A kitchen lights/6A upstairs lights/6A smoke alarms/20A utility room sockets/32A living room sockets.

 

[Baddegg]

If there’s no spare ways I expect he’ll split the tails via a Henley and put in a small unit dedicated for the ev charger......or put the smokes in with the lights, I’d let whoever is designing it advice mate ?

 

[justeez81]

If there’s no spare ways I expect he’ll split the tails via a Henley and put in a small unit dedicated for the ev charger......or put the smokes in with the lights, I’d let whoever is designing it advice mate ?

Only issue is they have split the consumer unit with
A live and neutral block which has 25mm tails to consumer unit and 25mm tails to a smaller 2 way consumer unit for the loft. The blocks do have a 3rd slot for another tail in each of the love and neutral block. Do you think they might use it?

 

[snowhead]

Has the installer asked you to run 6mm cable?

The installer will sort out what is needed when they come to quote or to do the work.
Nothing you've described will be a problem for them.

 

[justeez81]

Has the installer asked you to run 6mm cable?

The installer will sort out what is needed when they come to quote or to do the work.
Nothing you've described will be a problem for them.

No I am getting a new driveway installed and will pre install the SWA before the EV box is installed. I also intend on doing the cable run as that keeps installer costs down as well

 

[JBW175]

As above, the person installing will know what needs doing and carry out the works accordingly.

Leave it to them and all will be good. ??

 

[JBW175]

No I am getting a new driveway installed and will pre install the SWA before the EV box is installed. I also intend on doing the cable run as that keeps installer costs down as well

Who’s designed the circuit? Have you been told what size cable to use? How longs the run? Have you calculated VD / Zs?

You can’t scrimp on safety, leave it to the electrician...

 

[justeez81]

As above, the person installing will know what needs doing and carry out the works accordingly.

Leave it to them and all will be good. ??

Thanks for the advice but I don't want to be blindsided by a huge quote to upgrade the entire consumer unit if that makes sense

 

[driverman]

Whilst no need to comply with regs, I would suggest lay black pvc ducting for the SWA under your drive.
Something like 50mm diameter Polyducting

 

[justeez81]

Who’s designed the circuit? Have you been told what size cable to use? How longs the run? Have you calculated VD / Zs?

You can’t scrimp on safety, leave it to the electrician...

Thanks for the comment. I have designed the circuit. 8m run of 6mm is fine on VD and Zs. A 6mm SWA is perfect for a 7kW Mode 2 single phase charger

 

[Spoon]

No I am getting a new driveway installed and will pre install the SWA before the EV box is installed. I also intend on doing the cable run as that keeps installer costs down as well

The electrician cant sign off on the cable you have installed if he can't inspect it all. He may also refuse to sign it as he wasn't there when the cable was installed. Best to ask the installer first.
Ask about you installing some conduit for him?

Thanks for the advice but I don't want to be blindsided by a huge quote to upgrade the entire consumer unit if that makes sense

The EV needs a type A RCD. I doubt the RCD in the existing CU's are that type, so may not fit the cable into it. It all depends.
What does the small CU have?
He may just replace this one. Only a site visit can confirm this.
What EV are you getting?

 

[justeez81]

Whilst no need to comply with regs, I would suggest lay black pvc ducting for the SWA under your drive.
Something like 50mm diameter Polyducting

Yes the driveway contractor said he will install one, although a ducted SWA is slightly down rated over that of a laid direct onr

 

[driverman]

Thanks for the comment. I have designed the circuit. 8m run of 6mm is fine on VD and Zs. A 6mm SWA is perfect for a 7kW Mode 2 single phase charger

I’d use 3 core SWA cable
Why not go for 10mm. That will ensure you’re covered re loading plus spare capacity if needed further down the line. Bigger car!

 

[Spoon]

I’d use 3 core SWA cable

Might not need it, depending on the EV..

 

[justeez81]

The electrician cant sign off on the cable you have installed if he can't inspect it all. He may also refuse to sign it as he wasn't there when the cable was installed. Best to ask the installer first.
Ask about you installing some conduit for him?



The EV needs a type A RCD. I doubt the RCD in the existing CU's are that type, so may not fit the cable into it. It all depends.
What does the small CU have?
He may just replace this one. Only a site visit can confirm this.
What EV are you getting?

I’d use 3 core SWA cable
Why not go for 10mm. That will ensure you’re covered re loading plus spare capacity if needed further down the line. Bigger car!

Not a bad idea but the most you'd get from a single phase is EV box is 7kw. You can get 15bor 22kW chargers but they require 3 phase.

 

[driverman]

Might not need it, depending on the EV..

I was just thinking ease of getting a good earth connection in these modern day plastic boxes instead of relying solely on the SWA glands and banjo connections

 

[Spoon]

Was you meant to put a reply to my post that you copied in your post above, or was it copied by accident?

 

[Spoon]

I was just thinking ease of getting a good earth connection in these modern day plastic boxes instead of relying solely on the SWA glands and banjo connections

The EV might need to be TT arrangement, depending of EV of course.

 

[driverman]

The EV might need to be TT arrangement, depending of EV of course.

Good point, I was just assuming attached to house.

 

[justeez81]

Good point, I was just assuming attached to house.

It will require an earth rod which they will install and the EV Box will be TT. Would they still require a Type A RCD at the consumer unit side or just a 32A Mccb

 

[driverman]

Was you meant to put a reply to my post that you copied in your post above, or was it copied by accident?

Sorry Spoon, have I done something that I shouldn’t of? I’m using my phone for this for the first time.

 

[pc1966]

It all depend on the EV charger. Some only need the supply basic protection, so if SWA cable then a MCB is fine, others demand at least a type A RCD/RCBO or possibly the eye-wateringly expensive type B.

For now I would put in big enough and smooth bend duct so you can pull through whatever is needed later. You won't save much (if anything) on the cable cost, what you can save over the installer doing everything is the donkey work of duct or cable burial.

With duct you can also run network cable along side SWA if it is a smart charger that regulated household use versus charge rate if you get close to the incoming supply limit.

 

[Spoon]

Good point, I was just assuming attached to house.

Even if the EV is attached to the house it still might need to be TT. Some require it that way.

Sorry Spoon, have I done something that I shouldn’t of? I’m using my phone for this for the first time.

That was directed at @justeez81 post #15 mate, not you.

 

[Spoon]

With duct you can also run network cable along side SWA if it is a smart charger that regulated household use versus charge rate if you get close to the incoming supply limit.

Doncaster Cables do one that is power and data combined.

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Doncaster Cables is the largest British owned general wiring manufacturer in the UK. We have been manufacturing cables since 1984 and among our current staff alone we have over 1000 years direct cable manufacturing experience. Throughout this time we have continued to develop in to an...

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[Risteard]

No I am getting a new driveway installed and will pre install the SWA before the EV box is installed. I also intend on doing the cable run as that keeps installer costs down as well

Personally I charge extra if someone has done that, as it always adds to the work I need to do to correct it.

 

[Risteard]

I doubt the RCD in the existing CU's are that type

Even if it was, each and every EVSE must have its own dedicated RCD.

 

[justeez81]

Personally I charge extra if someone has done that, as it always adds to the work I need to do to correct it.

Thats why I want a curled up SWA ready for thr installer to connect the ev, earth rod and consumer unit

 

[Spoon]

Thats why I want a curled up SWA ready for thr installer to connect the ev, earth rod and consumer unit

How does the installer know that the cable running under the new driveway isn't damaged or installed correctly, if he cant see it?
Again, what EV are you getting?

Why not just do what @driverman suggests in post #9 and just lay in some ducting?