Charger connected to secondary consumer unit

[Mr Miserable]

I need some advice on whether this idea is a go'er or not.

I cancelled installation of a charger because it was clear that the installer was going to tack a big black cable along the front of the house and along the side to install the charger. There was going to be absolutely zero effort to conceal the cable in any manner whatsoever.
I spoke to my local sparky (in the pub, where else?) and he suggested he could run an armoured cable internally from the main supply/consumer unit under the floorboards and then into the garage to a new consumer unit capable of taking lots of amps. He suggested that the charger installation could then just connect to that consumer unit. He isn't qualified to install a charger and I've read enough on this forum to realise that there is more to this wiggly amp business than meets the eye.

Is this viable and if so what should I be specifying for the components?

 

[ewoodrick]

There are always options. The second option sounds a lot more expensive though

 

[Glan gluaisne]

Sounds fine, but it's not that straightforward.

The maximum length of unprotected 25mm² cable from the cut out is 3m, so any run of SWA will need to be protected against over-current, so that means fitting a suitable switch fuse, or better, form of protection at the feed end of the SWA. This means that an additional small box should really be fitted near the existing CU, in order to terminate the length of SWA. It's not normally very easy to terminate SWA glands at the CU itself, anyway, plus using a spare way in the CU to supply the charge point isn't ideal, for several reasons.

If fitting a box to terminate the SWA and tap into the incoming tails, then it makes sense to fit a Type A (or Type B) RCBO in that box, both to provide over-current protection for the cable and to provide earth leakage protection for the charge point. There also needs to be thought given to earthing, as some charge points require a TT earth system (an earth electrode near the charge point) and some don't. This has an impact on the way the SWA is terminated and also the RCBO type used.

 

[pgkevet]

No approved installer would trek out to the sticks, here, so I used local sparky. In my case armoured cable from main consumer unit in utility room, out the wall and tucked under the gable end eves to the top then overhead wire to barn and sub consumer unit. Since I wasn't going to get the grant I went with the tesla charger. We took the opportunity to add extra 13A sockets inside and outside the barn and new security lights. Outside sockets make it easy to plug in vaccuums and jetwashers.

If you want to use a grant funded charger then getting your sparky to run the second consumer unit only is a fair compromise so long as your main fuse has enough capacity for your needs. I have 100A coming into the house and 2 sub consumer units (the barn one and one in my hobby shed) both are 60A and I just have to use commonsense not to have the car on charge while immersion and oven are on and start using a welder.

 

[nufan]

Mine will be run off the meter box - with ‘Henley Blocks’ splitting the feed off the back of the meter. Supply has 100A fuse.

I’ll then have a second mini consumer unit (in the meter box) off which the Andersen will go.

Thought I’d mention in case your meter box is closer than your consumer unit/fuse box. Keeps EV away from house power as a positive. Power company should be fine with it - but small risk they might kick off if done untidily.

HTHs

 

[Glan gluaisne]

Mine will be run off the meter box - with ‘Henley Blocks’ splitting the feed off the back of the meter. Supply has 100A fuse.

I’ll then have a second mini consumer unit (in the meter box) off which the Andersen will go.

Thought I’d mention in case your meter box is closer than your consumer unit/fuse box. Keeps EV away from house power as a positive. Power company should be fine with it - but small risk they might kick off if done untidily.

HTHs

Be aware that suppliers can be a bit fussy about putting consumer equipment in "their" meter box. They will allow an isolator switch, or switch fuse, but may well throw a wobbly if you stick another enclosure in there.

The reason for this is because there's only just enough room in a standard meter box for the largest supplier-side equipment (used to be a white meter and teleswitch combination, but now a smart meter plus additional comms box is almost as large).

 

[nufan]

Thanks Jeremy - forewarned/forearmed etc.

I don’t have a SMETS2 smart-meter - and figured installation of that would be the point any other meter box gear might be flagged up. I’m hoping the meter reader won’t care.

So scoped getting one in before the EV-point addition (what’s the right lingo: can I call it a charger given that’s in the car as I understand?!).

My gas meter is partially in the ground though (submerged cabinet or something like that is the term), and that’s a contra-indication for a SMETS2 install - soooo - can’t do that.

Installer seems fine with the option - and he’s an Andersen fitter. Of course he’s not the DNO though...so I might get stung!

Mr Miserable: if you need a fitter - I can recommend one that seems helpful pre-install in Surrey.

 

[Glan gluaisne]

Meter readers aren't usually bothered, but suppliers can be. SSE kicked up a fuss when they came to change my meter from a standard one to a (much larger) E7 one, as I had a small enclosure right at the lower right corner with a couple of DP MCBs feeding outdoor circuits. The fitter's initial reaction was to walk away and request that I be ordered to remove the equipment from "their" meter box. I persuaded him that I'd rearrange things and fit a new external box for the consumer side stuff and he reluctantly agreed to make the meter change. The new E7 meter is a great deal larger than the old meter, so I can see his point. A smart meter would be even larger, and most probably wouldn't fit.

The AC car charging connection box is either just a charge point, or an EVSE (Electric Vehicle Supply Equipment). The AC charger is built in to the car, often referred to as the On Board Charger, or OBC.

 

[nufan]

Thanks Jeremy - all good stuff to know.

 

[Mr Miserable]

Sounds fine, but it's not that straightforward.

The maximum length of unprotected 25mm² cable from the cut out is 3m, so any run of SWA will need to be protected against over-current, so that means fitting a suitable switch fuse, or better, form of protection at the feed end of the SWA. This means that an additional small box should really be fitted near the existing CU, in order to terminate the length of SWA. It's not normally very easy to terminate SWA glands at the CU itself, anyway, plus using a spare way in the CU to supply the charge point isn't ideal, for several reasons.

If fitting a box to terminate the SWA and tap into the incoming tails, then it makes sense to fit a Type A (or Type B) RCBO in that box, both to provide over-current protection for the cable and to provide earth leakage protection for the charge point. There also needs to be thought given to earthing, as some charge points require a TT earth system (an earth electrode near the charge point) and some don't. This has an impact on the way the SWA is terminated and also the RCBO type used.

Thanks Jeremy.

I was kinda hoping that it wasn't going to be much of an issue but I had that nagging feeling that it wouldn't be so simple - hence my post.
I'll speak to the sparky again and get some meat on to the bone to ensure we have all the bases covered.
I was thinking of having a pod point fitted which may not need a earth. (Although my house is PME)

 

[Glan gluaisne]

The stuff needed isn't expensive. Assuming that the charge point will be OK on a Type A RCBO, then the rough costs for materials at the meter end would be:

Metal 4 way enclosure ~£15
DP isolator switch ~£10 (arguably you could get away without this, and just use the RCBO)
DP Type A RCBO ~£10
Pair of Henleys ~£10
Metre of tails ~ £10

To this you'd have the SWA at ~£3/metre, plus clips, glands etc, and wiska box or similar to terminate the SWA near the place where you want to connect the charge point.

You should get a reduction in the installation price for the charge point, as at least £60 of the above stuff would be needed for any standard installation.

 

[Mr Miserable]

What sort of amperage should I be looking for the RCBOs etc
I assume 32A for the charger.

 

[Radders]

What sort of amperage should I be looking for the RCBOs etc
I assume 32A for the charger.

My Podpoint is run off of my Garage FB, this has a 32A breaker and double pole isolator installed by podpoint.

My garage board (which was just installed for ease) just runs garage sockets and power, and is served by a 40A MCB in my main board, luckily when i put the garage board in i fed it via 10mm cable so plenty of capacity to take the un planned podpoint (7Kw). all very straight forward and no issues.

 

[Glan gluaisne]

40 A for a 32 A charge point. 6mm SWA should be OK, unless the cable length is several tens of metres or more. 32 A is pushing it for an RCBO rating, as the RCBO will tend to run a bit warm when run at full load for hours on end. As long as the RCBO is rated to protect the cable rating then it'll be fine if over the max charge point current. If the charge point has integral DC leakage current detection, then a normal Type A RCBO will be OK. I tend to stick to using Garo RCBOs, as (so far) I've not had one fail (no connection, other than as a customer): Garo RCBO 1+N 40A char B 6kA Type A | Distribution and Control | GARO

 

[MaDProFF]

Thanks Jeremy.

I was kinda hoping that it wasn't going to be much of an issue but I had that nagging feeling that it wouldn't be so simple - hence my post.
I'll speak to the sparky again and get some meat on to the bone to ensure we have all the bases covered.
I was thinking of having a pod point fitted which may not need a earth. (Although my house is PME)

I have a pod point it has an earth cable, not saying it does not need one, but installer went to great lengths in checking the earth connection.

It is very easy to install a charger, it is all about the correct size cable, and the correct RCB or what ever it is called now.
Supplier Company cannot really do much about anything after incoming fuse, but off if he has no room to work and cannot fit a new metre then he will walk away. (unless he thinks it is dangerous).

 

[Mr Miserable]

Thanks for the advice - much appreciated.

 

[Avendit]

With the original quote, could you offer to do the wire pulling under the house for them? I've always assumed this would be an option if they didn't like the distance or anything? You do all the annoying squeezing into awkward spaces and guddling around in the house's nether regions and they deal with the ends of the cable...

 

[MaDProFF]

Armoured cables are not the easiest things to move around, though I guess run some real heavy duty T & E to the point before it goes outside. (unless garage is part of the house), even 6mm T & E is hard work.

On a side note, my garage supply which is outside is feed just after the main fuse, and runs into a secondary consumer unit, (just one fuse) then armoured to the outside garage, and then there is a 3rd consumer unit in the garage to feed lights, sockets, 16A commando, and the pod point charger, which installer put another box with an RCB or correct term used now.

 

[Mr Miserable]

With the original quote, could you offer to do the wire pulling under the house for them? I've always assumed this would be an option if they didn't like the distance or anything? You do all the annoying squeezing into awkward spaces and guddling around in the house's nether regions and they deal with the ends of the cable...

It's quite a job - carpets and floorboards lifted, feeding SWA from front of house to rear and into garage at side. Not a 10 minute job.
I don't mind paying to have it done properly. Clearly my bit in the equation is clearing the two bedrooms sufficiently so carpets can easily be lifted. Our meter is next to our front door and the consumer unit is in the hallway and so making sure the extra box here is aesthetically pleasing is equally important. My wife doesn't want the hallway to look like the inside of a submarine which is a quite a clever description for me - I understand what she means!

 

[MidhurstNigel]

My gas meter is partially in the ground though (submerged cabinet or something like that is the term), and that’s a contra-indication for a SMETS2 install - soooo - can’t do that.

I've got the same set-up and the meter installer (who thought he was going to do both gas and electric) was happy to phone his office and change the order to 'electric only smart meter' and then install a SMETS2 on the electric only. This was done as part of my sign-up for Octopus GO