[BillTheButcher]

Hello,

I've contacted a few local EVHS-approved installers to get quotes for a home charger installation. The first one has replied to say that the charger can't be connected to the fusebox in the garage; it will have to run from the main fusebox in the house. This is the fusebox in the garage:

Disclaimer (in case it wasn't already obvious): I know nothing about electricity.

Can someone tell me why the charger can't be connected to this fusebox? The only things connected to it at the moment are an LED security light outside, an internal light and a couple of standard 3-pin sockets.

Thanks.

 

[cah197]

It needs a dedicated MCB/RCBO. You don’t have any spare ways.

Also a charger needs a 32 Amp breaker, not 16 amps.

The cable to the garage may not be up to spec either.

 

[BillTheButcher]

It needs a dedicated MCB/RCBO. You don’t have any spare ways.

Also a charger needs a 32 Amp breaker, not 16 amps.

The cable to the garage may not be up to spec either.

Thank you. In the fusebox pictured, is the breaker on the left 6 amps and the one on the right 16? If the charger needs 32, does that mean that, even if the existing ways were repurposed (e.g. by disconnecting the existing 3-pin sockets) it still wouldn't be up to the job? Please forgive my ignorance. 🙈

 

[cah197]

Possibly, but it’s hard to know without doing a proper inspection. That’s what the electrician does.

I’m sure he’ll explain his reasons, but there may be more to it than just the MCBs.

Interesting you have a 100A main breaker in the garage. What’s the rating for the house main fuse?

 

[BillTheButcher]

Possibly, but it’s hard to know without doing a proper inspection. That’s what the electrician does.

I’m sure he’ll explain his reasons, but there may be more to it than just the MCBs.

The reason he's given:
"No, alas the load is so great it has to come from the main fuseboard in the majority of installations."

Interesting you have a 100A main breaker in the garage. What’s the rating for the house main fuse?

This is the main fusebox in the house:

Just above the left-hand red switch, it says "100A" which I assume is a rating of 100 amps.

Looking at that photo... does the garage only have 16 amps?

I also asked if he could run directly from the meter box (it's outside, halfway to the garage) but he said absolutely not.

 

[Tandy0]

He just wants to charge you for running a lot of cable.

 

[javadude]

We have a charger running off a consumer unit in the garage but then the consumer unit and the cable to the garage were new at the time the charger was fitted so adequately spec'd.

 

[BillTheButcher]

He just wants to charge you for running a lot of cable.

That was my first thought.

He's also just told me that the main fuseboard is full so "we will need to create a spare way somehow."

 

[Jrtev]

Whoa whoa whoa....

What type of charger are you getting?

 

[BillTheButcher]

Whoa whoa whoa....

What type of charger are you getting?

I was looking at the Ohme but I'm open to suggestions (I'm not on a variable tariff so I don't think getting a smart charger will be of any benefit).

 

[Jrtev]

Your Hager DB is feeding your garage DB with a 16a mcb. This mcb can be changed if your cable is big enough. Have a look on your cable in the garage and see if you can see anything like 6mm X 3 core.

Approx how far is the house dB to your garage dB?

The 100amp double pole switches are isolation switches, ignore that ratings.

 

[Jrtev]

I also asked if he could run directly from the meter box (it's outside, halfway to the garage) but he said absolutely not.

Send me a photo from inside your "meter box"

 

[BillTheButcher]

Your Hager DB is feeding your garage DB with a 16a mcb. This mcb can be changed if your cable is big enough. Have a look on your cable in the garage and see if you can see anything like 6mm X 3 core.

I don't know what 6mm x 3 core looks like. Is this any help?

Approx how far is the house dB to your garage dB?

About 17m.

The 100amp double pole switches are isolation switches, ignore that ratings.

I don't know what that means.

I also asked if he could run directly from the meter box (it's outside, halfway to the garage) but he said absolutely not.

Send me a photo from inside your "meter box"

I'll take a photo tomorrow morning and post it here. Thanks.

 

[Jrtev]

On that black cable they'll be imprinted writing with the cable size on. Have a close look down the cable to see, but it looks small to me, 2.5mm 3 core would be my guess.

 

[mikegs]

That's almost exactly what my basic garage supply is - 6A lights, 16A sockets. Probably 2.5mm cable.

There's about a 0.0001% chance the builders installed a cable fat enough to feed an EVSE with more than you could get by plugging the granny charger into a garage socket ... because 17m of extra copper = less profit.
At a pinch you might run a 16A EVSE by repurposing the socket circuit - but then you wouldn't have the sockets.

 

[BillTheButcher]

That's almost exactly what my basic garage supply is - 6A lights, 16A sockets. Probably 2.5mm cable.

There's about a 0.0001% chance the builders installed a cable fat enough to feed an EVSE with more than you could get by plugging the granny charger into a garage socket ... because 17m of extra copper = less profit.
At a pinch you might run a 16A EVSE by repurposing the socket circuit - but then you wouldn't have the sockets.

I could live without the sockets. I rarely use them and access to sockets in the house is nearby.

 

[Tandy0]

If you could find a slightly larger consumer unit for the garage, I think you could probably keep the sockets. Any overload would trip the breaker in the house.

 

[Drewby80]

Strikes me that you could move the security alarm onto a fused spur off the ring main so it hasn’t got a dedicated breaker and with the spare way it’s freed up install a 40a breaker run a 6 or 10mm cable (armoured if needs be) put a small new sub board in the garage with n RCBO in it and stick the charge point on the end of that?

There are MANY more people on here more conversant with letter and verse of the regs than me.....

Would that work guys??

 

[mikegs]

Strikes me that you could move the security alarm onto a fused spur off the ring main so it hasn’t got a dedicated breaker and with the spare way it’s freed up install a 40a breaker run a 6 or 10mm cable (armoured if needs be) put a small new sub board in the garage with n RCBO in it and stick the charge point on the end of that?

There are MANY more people on here more conversant with letter and verse of the regs than me.....

Would that work guys??

In theory, yes.
BUT
In practice, if an electrician messes with a consumer unit he needs to take responsibility for the whole caboodle, usually involving (re)testing and paperwork submission. At ££/hour that gets expensive fast.
Hence the superficially bonkers but in reality easier and more economical solution of leaving the house CU well alone and fitting a second CU to feed the EVSE.

It's a bit like quantum mechanics

 

[freddym]

Possibly, but it’s hard to know without doing a proper inspection. That’s what the electrician does.

I’m sure he’ll explain his reasons, but there may be more to it than just the MCBs.

Interesting you have a 100A main breaker in the garage. What’s the rating for the house main fuse?

The 100A main breaker is just a standard switch and doesn't indicate in any way whatsoever the rating of the supply cable and supply protection