Home charger, but Consumer Unit already full

[M4cruiser]

Just a question to you EV experts and/or electricians:-

When installing a home wall-box (7Kw), does it wire through the existing consumer unit? I saw a fixed quote for installation but there are a lot of clauses, i.e. they can charge more if the existing CU isn't adequate. That sounds like a lot of money.

Can they just add another (smaller) CU without replacing the whole of the existing one?

Or is there a better way? I wouldn't really want another 30 amps wired through any existing circuit. Apart from lights and sockets, we have a larger-current circuit, for the cooker, but nothing else that I can see.

[Geffg]

Can always split the mains to supply a small consumer unit and feed it from that.

[motco]

Geffg said:

Can always split the mains to supply a small consumer unit and feed it from that.

Exactly what the installer did for mine.

[Bikerjon]

Interested in this myself as I have a similar situation and just about to take the plunge into EV ownership...

Having done a bit of research it seems that with an outdoor meter some installers wire an additional CU from it and put it in a weather proof box. I'm hoping I'll be offered this as it will save a lot of hassle - but I don't know if there's any disadvantages to doing it that way.

[number2]

Bikerjon said:

Interested in this myself as I have a similar situation and just about to take the plunge into EV ownership...

Having done a bit of research it seems that with an outdoor meter some installers wire an additional CU from it and put it in a weather proof box. I'm hoping I'll be offered this as it will save a lot of hassle - but I don't know if there's any disadvantages to doing it that way.

That's what Octopus did for me. I didn't ask for any specific approach so I assume it's standard.

[paradigital]

motco said:

Exactly what the installer did for mine.

Same. I’ve got a small additional unit with just the EVSE and the Solar PV/Inverter in it.

[stewilko]

This is what they did with ours (outside meter). They split the supply post meter with tails going into the house CU and a separate 40amp breaker for the charger.

[CharlesElliott]

It is common, but most suppliers don't actually allow additional equipment to be installed in the meter box.

[chrisch77]

I believe it is not the preferred method to add a 7kw car charger circuit to an existing consumer unit and it should be on a separate feed with its own CU. Reasons are that you don’t want a car charger fault to trip out all or some of the house circuits in the event of a fault, and also if your current CU isn’t up to current regs (e.g. metal housing) then it would have to be upgraded anyway to do any work to add circuits to it.

[phil4]

Ours is a henley block after the meter, one set off to the main CU, the other to a small 2 fuse type CU for the charger. Not in the meter cupboard as we don't have one.

[M4cruiser]

Thank you for the replies, that's encouraging, I think a smaller separate CU (from the outside meter) would work for me. The wall-box itself needs to be only a short distance from the meter box.

[Basil Brush]

phil4 said:

Ours is a henley block after the meter, one set off to the main CU, the other to a small 2 fuse type CU for the charger. Not in the meter cupboard as we don't have one.

I asked Octopus when they did ours, as we have 2 CUs already and had plenty of spare slots, but it was the only way they would do it. I now have 3 CUs.

[Geffg]

A lot of the time they’ll put in another cu so they don’t have to be responsible for the existing cu etc.

[TheDeuce]

CharlesElliott said:

It is common, but most suppliers don't actually allow additional equipment to be installed in the meter box.

True, but it is incredibly common and I've googled it to death - yet to find an example of the dno making a fuss other than some thoughtless installations which actually made it impossible for them to maintain their existing kit in the cabinet.

Ours is installed that way, I think they all are around here. The rules on cabinet size and right of use need updating imo, because it's an overtly sensible and practical way of installing a charger.

[M4cruiser]

I've thought of another question, does it come with an isolator inside the house, or some other security mechanism, to stop someone else plugging in their car when the box owner is on holiday for example?

[TheDeuce]

M4cruiser said:

I've thought of another question, does it come with an isolator inside the house, or some other security mechanism, to stop someone else plugging in their car when the box owner is on holiday for example?

You can set them to not charge unless a key fob is tapped etc.

[blank]

TheDeuce said:

M4cruiser said:

I've thought of another question, does it come with an isolator inside the house, or some other security mechanism, to stop someone else plugging in their car when the box owner is on holiday for example?

You can set them to not charge unless a key fob is tapped etc.

That would very much depend on the charger and not many home units support RFID.


You can usually switch them off from the circuit breaker in the consumer unit, or the open PEN fault box (if fitted).

If these are outside then an additional switch inside the house will be a fair bit of work.


You should be able to disable any "smart" home charger via its app though.

[TheDeuce]

blank said:

TheDeuce said:

M4cruiser said:

I've thought of another question, does it come with an isolator inside the house, or some other security mechanism, to stop someone else plugging in their car when the box owner is on holiday for example?

You can set them to not charge unless a key fob is tapped etc.

That would very much depend on the charger and not many home units support RFID.


You can usually switch them off from the circuit breaker in the consumer unit, or the open PEN fault box (if fitted).

If these are outside then an additional switch inside the house will be a fair bit of work.


You should be able to disable any "smart" home charger via its app though.

That's why I added the 'etc', there's always a way to prevent/authorise them charging.

Although we leave ours on instant charge and 4 years later I can confirm nobody has helped themselves to it.

[Turtle Shed]

Just to add to the thread, an electrician did this exact job for me.

Moved into a new house, brought my old British Gas Polar charger with us. I fitted the charger to the wall and ran a 2.5mm cable back to the exisiting consumer unit cabinet. (Straight through the wall, bit of ducting inside up to the roof (bungalow), couple of metres and back down again.

Second consumer unit supplied, fitted and tested, plus connecting my garage supply to the new CU cost about £180.00.