Home Charge Points Discussion and Suggestions [megathread]

[Glan gluaisne]

If only the main electrics were that new, the fuse box (can't really call it a consumer unit) is an old style with no RCD just MCBs. The solar is separate in its own RCD protected unit and the EV charger will connect to that. I lost interest in electric installations when they stopped us from doing them, I rewired my whole house 30 years ago when it was allowed but given I'm not allowed to touch anything my interest in researching and keep up with the regs has gone on that side instead it is 6 gang extensions into 6 gang extensions into 6 gang extensions etc into the one double socket in the office whereas in the past I would have wired it all properly into the ring. Looking forward to moving to a new house with a proper amount of sockets in the rooms sometime soon.

There are no UK laws or regulations that prevent anyone from DIY'ing their own electrical installation, with the sole exception of items subject to government grant aid, like a partially grant funded charge point or heat pump installation. Obviously there's a requirement that the work be done by a competent person, but I DIY all my own stuff, have done for decades. There's also a requirement (in England and Wales, but not Scotland) that some parts of an electrical installation be signed off by building control, under Part P, or that the person doing the work is a member of a body that allows them to approve work under Part P. However, a homeowner can just request that their local BC organisation do this for any DIY work, and BC have a legal obligation to offer to inspect, test and sign off such work. Part P only applies to some aspects of an electrical installation anyway, for example I can change a consumer unit for a new one, rewire most of the house and not need a Part P sign off.

There is a need for a Part P sign off for any new electrical installation outdoors, like a power outlet or EV charge point, but again, this can be just done via a minor works application to building control, following a DIY installation by a competent person.

You can perfectly legally add additional outlets to a ring final, or fit spurs to a ring final to run an additional outlet, there is no law or regulation preventing that at all, and if none of the new outlets are outside then there's no need to get a Part P sign off, either.

With regard to RCD protection, a charge point must be connected to an RCD that is DC tolerant, so a Type B, unless the charge point has integral DC tolerant earth leakage protection, in which case a Type A is acceptable. A Type AC (very common in older installations) is not acceptable. In addition, a charge point, like a hot tub, swimming pool pump/heater, metal framed greenhouse, caravan hook up point, etc, must have some form of open PEN fault protection. This can be either an earth electrode and RCD or one of the open PEN connection boxes now available. As this is notifiable work under Part P (in England and Wales) building control will not sign off on a DIY charge point installation unless it meets the regs.

Moderator comment - a more comprehensive follow on from this post can be found at DIY electrical work and safety

 

[Type2]

I had a 22KW Andersen installed last November and am very happy with it. I’m looking to get a second 22KW one installed as we will shortly have four EVs in our household.

I presume you must have a three phase supply to support a 22KW charger, but is it possible to have two of them?

 

[26ct2143]

I presume you must have a three phase supply to support a 22KW charger, but is it possible to have two of them?

If your supply is up to, you can have as many as you want.
If you were charging 2x model 3, then they max out at 16amp/phase on 3 phase, so you'd need 32amp/phase to supply both on full power.
If you were close to the limit of the supply, a load balancing system might be needed to ensure the total (of the 2 chargers) doesn't exceed the supply's capacity.

 

[Glan gluaisne]

I presume you must have a three phase supply to support a 22KW charger, but is it possible to have two of them?

A typical UK domestic three phase supply will be fused at 100 A per phase and probably rated at around 15 kW per phase (varies a bit depending on the local LV network diversity assumptions). Depending on the total load, and more specifically the individual phase load balance, then it should be just about OK to install two 22 kW charge points. Few EVs can charge at 22 kW, though. The Model 3, for example, can only charge at 11 kW when connected to a 22 kW 3 phase charge point, as its chargers can only deliver 16 A per phase. The 3 phase chargers in other EVs may have a higher rating, but last time I looked there were very few that were higher than 11 kW.

The other point is whether or not a high charge rate is actually needed. A single phase 7 kW charge point is enough to charge a car overnight that's driven over 300 miles a day.

 

[Hurricane]

Yes, I have a three phase supply with three big, fat 100A fuses. Great to know from the comments above that I can probably get another charger.

Do I really need a 22KW charger? No, but I got one because I can. I wanted to future proof. I’m a little peeved that my daughter can charge her Zoe at 22KW while my all singing, all dancing M3 is restricted to 11KW.

 

[26ct2143]

The other point is whether or not a high charge rate is actually needed. A single phase 7 kW charge point is enough to charge a car overnight that's driven over 300 miles a day.

That's a good point. Because you could install say 3x 7kw chargers 1 on each phase for 3 cars.

 

[MrBadger]

If your supply is up to, you can have as many as you want.
If you were charging 2x model 3, then they max out at 16amp/phase on 3 phase, so you'd need 32amp/phase to supply both on full power.
If you were close to the limit of the supply, a load balancing system might be needed to ensure the total (of the 2 chargers) doesn't exceed the supply's capacity.

The DNO may have a say in matters.

Charge point installation need to be approved by the DNO. First one is normally fine within certain constraints so can normally be retrospectively approved, although DNO may be obliged to do some upgrade work to support. But subsequent ones can be blocked by DNO, or they can pass on a big bill if any network changes required.

Other than if a charge point is fitted with OLEV when it is necessary, its not clear to me if its an offense to fit a charge point without notification - installation companies that I have dealt with will not fit a charge point even non OLEV installs without the info needed to inform the DNO, however one of these even refused to fit without getting prior approval which I know is BS, so possibly some posturing going on on their part. What is clear though that if a network problem is later found to be caused by non approved installs, then they are going to come down on you to rectify the problem.

Unfortunately my link to charge point and heat pump installs is no longer working, but a search on the ena website may find more info Energy Networks Association (ENA) - The voice of the networks

 

[26ct2143]

The DNO may have a say in matters.

Charge point installation need to be approved by the DNO. First one is normally fine within certain constraints so can normally be retrospectively approved, although DNO may be obliged to do some upgrade work to support. But subsequent ones can be blocked by DNO, or they can pass on a big bill if any network changes required.

Other than if a charge point is fitted with OLEV when it is necessary, its not clear to me if its an offense to fit a charge point without notification - installation companies that I have dealt with will not fit a charge point even non OLEV installs without the info needed to inform the DNO, however one of these even refused to fit without getting prior approval which I know is BS, so possibly some posturing going on on their part. What is clear though that if a network problem is later found to be caused by non approved installs, then they are going to come down on you to rectify the problem.

Unfortunately my link to charge point and heat pump installs is no longer working, but a search on the ena website may find more info Energy Networks Association (ENA) - The voice of the networks

don't really get that,
1x22kw charger could have the same draw as 3 x 7kw single phase chargers if 1 is on each phase.

 

[Hurricane]

The DNO may have a say in matters.

Charge point installation need to be approved by the DNO. First one is normally fine within certain constraints so can normally be retrospectively approved, although DNO may be obliged to do some upgrade work to support. But subsequent ones can be blocked by DNO, or they can pass on a big bill if any network changes required.

Other than if a charge point is fitted with OLEV when it is necessary, its not clear to me if its an offense to fit a charge point without notification - installation companies that I have dealt with will not fit a charge point even non OLEV installs without the info needed to inform the DNO, however one of these even refused to fit without getting prior approval which I know is BS, so possibly some posturing going on on their part. What is clear though that if a network problem is later found to be caused by non approved installs, then they are going to come down on you to rectify the problem.

Unfortunately my link to charge point and heat pump installs is no longer working, but a search on the ena website may find more info Energy Networks Association (ENA) - The voice of the networks

I wasn’t aware that the DNO needed to be informed about a charge point installation. I’m not entitled to the OLEV grant and the electrician who fitted my Andersen didn’t mention anything. He did, of course, check that my electricity supply was robust enough to support a 22KW unit, but with a potential 300A on tap that wasn’t going to be a problem.

 

[Glan gluaisne]

I wasn’t aware that the DNO needed to be informed about a charge point installation. I’m not entitled to the OLEV grant and the electrician who fitted my Andersen didn’t mention anything. He did, of course, check that my electricity supply was robust enough to support a 22KW unit, but with a potential 300A on tap that wasn’t going to be a problem.

Yes, this has been the case for some time, not just for charge points, but also for electric heating (like storage heaters), heat pumps or any heavy continuous demand. The DNO have a diversity method they apply to size their network, that relies on each house never drawing its maximum rated load for long periods of time. Some idea of these can be gleaned by looking at the size of fuse they fit on the LV network. Each phase from a typical small substation, supplying, say, 40 or 50 houses, will be fused at perhaps 400 A. Each house may well be fused at 100 A, but obviously if every house were to draw 100 A then the 400 A fuse at the substation would be overloaded.

The diversity assumptions seem to vary a bit from one area to another, but it's pretty typical for a 100 A fused supply to be assumed to be around 10 kW to 15 kW demand, as far as the network is concerned, not the theoretical 23 kW that might be implied from the fuse rating. If several houses on the same phase from a substation were to have 7 kW charge points installed, then, combined with the other normal household loads it would be possible to overload the substation, hence the reason the DNO has to be informed. They can do things like switch phases around, change the topology of the LV network, or even upgrade the substation, if the loads get too high because of lots of charge point installations.

Finally, your electrician should have undertaken a total demand calculation and submitted the request to the DNO, as a part of the normal process of installing a charge point like this. Often this may be combined with the request to the DNO to get the main fuse(s) pulled to isolate the supply in order to undertake the installation safely.

 

[26ct2143]

Yes, this has been the case for some time, not just for charge points, but also for electric heating (like storage heaters), heat pumps or any heavy continuous demand. The DNO have a diversity method they apply to size their network, that relies on each house never drawing its maximum rated load for long periods of time. Some idea of these can be gleaned by looking at the size of fuse they fit on the LV network. Each phase from a typical small substation, supplying, say, 40 or 50 houses, will be fused at perhaps 400 A. Each house may well be fused at 100 A, but obviously if every house were to draw 100 A then the 400 A fuse at the substation would be overloaded.

The diversity assumptions seem to vary a bit from one area to another, but it's pretty typical for a 100 A fused supply to be assumed to be around 10 kW to 15 kW demand, as far as the network is concerned, not the theoretical 23 kW that might be implied from the fuse rating. If several houses on the same phase from a substation were to have 7 kW charge points installed, then, combined with the other normal household loads it would be possible to overload the substation, hence the reason the DNO has to be informed. They can do things like switch phases around, change the topology of the LV network, or even upgrade the substation, if the loads get too high because of lots of charge point installations.

Finally, your electrician should have undertaken a total demand calculation and submitted the request to the DNO, as a part of the normal process of installing a charge point like this. Often this may be combined with the request to the DNO to get the main fuse(s) pulled to isolate the supply in order to undertake the installation safely.

Interesting and informative as usual, thanks.
I live on a farm with it's own transformer. Since I pay a capacity charge (every month) for 200A and have 200A fuses.
Surely I would not need to inform them of any equipment I install as long as I always remain within the 200A?
Since they are effectively required to supply this on the contract.

 

[Glan gluaisne]

Interesting and informative as usual, thanks.
I live on a farm with it's own transformer. Since I pay a capacity charge (every month) for 200A and have 200A fuses.
Surely I would not need to inform them of any equipment I install as long as I always remain within the 200A?
Since they are effectively required to supply this on the contract.

Yes, sorry, I was referring to domestic supplies, where the supply from a typical PMT substation will be shared amongst lots of consumers, rather than the industrial/commercial supply you have. You can run right up to your PMT limit of 200 A per phase, as there are no other users connected to it.

 

[26ct2143]

Yes, sorry, I was referring to domestic supplies, where the supply from a typical PMT substation will be shared amongst lots of consumers, rather than the industrial/commercial supply you have. You can run right up to your PMT limit of 200 A per phase, as there are no other users connected to it.

Ah thanks for that,
Yes I can understand in a domestic situation it must be hard for the DNO to 'keep the balance', without having the right info.

edit: Could get interesting in the next 5 years or more as more domestic chargers are installed

 

[Glan gluaisne]

The typical way that balance is maintained with new builds is to wire each alternate house of the same type down a street on a different phase, in sequence. So the first house will be on L1, second on L2, third on L3, fourth on L1, fifth on L2, etc. Usually that does a pretty good job of keeping things balanced. Worst case for the DNO would be if every third house down the street fitted a charge point, which would seriously screw up the balance if they all chose to charge at the same time overnight, as all the charge points would be on the same phase.

 

[Hurricane]

Interesting and informative as usual, thanks.
I live on a farm with it's own transformer. Since I pay a capacity charge (every month) for 200A and have 200A fuses.
Surely I would not need to inform them of any equipment I install as long as I always remain within the 200A?
Since they are effectively required to supply this on the contract.

My property is quite isolated and is also served by its own transformer. Does this mean I wouldn’t be affected by load diversity?

 

[Glan gluaisne]

My property is quite isolated and is also served by its own transformer. Does this mean I wouldn’t be affected by load diversity?

Possibly, although in all probability, if it's not an industrial/commercial supply then diversity will just apply to the 11 kV supply to the PMT, perhaps. If you pay a capacity charge then you're free to use up to that, if you don't, then there may well be a limit. The DNO will have almost certainly have noted this when your electrician installed the charge point, anyway.

FWIW, I found recently that the DNO seem to routinely check and make sure their records are up to date whenever they do work in an area. We had a problem just after Christmas and the DNO chap that came out spotted one of the charge points and checked they had it recorded, as a routine part of his job.

 

[Hurricane]

Possibly, although in all probability, if it's not an industrial/commercial supply then diversity will just apply to the 11 kV supply to the PMT, perhaps. If you pay a capacity charge then you're free to use up to that, if you don't, then there may well be a limit. The DNO will have almost certainly have noted this when your electrician installed the charge point, anyway.

FWIW, I found recently that the DNO seem to routinely check and make sure their records are up to date whenever they do work in an area. We had a problem just after Christmas and the DNO chap that came out spotted one of the charge points and checked they had it recorded, as a routine part of his job.

Very informative, thank you. Clearly I need to make sure my DNO knows about my 22KW Andersen, especially if I’m thinking of installing a second one.

 

[Glan gluaisne]

I'd be inclined to wait until you want to fit a second one, and then tell them. No point in potentially creating an issue with them now, IMHO.

 

[Rustybkts]

Has anyone seen these available from Amazon and stocked in the UK. Sourced I am sure from China but the most compact and affordable Type B I've seen yet.
I purchased the one in the box to upgrade my old install from a standard RCBO to better protection.
https://www.wced.co.uk/electrical-vehicle-charging
https://www.amazon.co.uk/gp/product/B08CZWPQYC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[Glan gluaisne]

Never heard of the brand, TBH. Be interesting to see an independent review, especially as it probably comes from China and that part of the world has a bit of a reputation for manufacturing some extremely dodgy electrical equipment. For example, a day or so ago I spotted this video, of a Chinese made 3 phase "MCB". It carries the right IEC spec number on the front, but in reality offers no protection at all, it's just a fake, made to look and feel as if it functions:

There has also been a well-known issue with Rolec RCBOs, that are also sourced from China and have been known for a long time to just burn out one of the terminals when used in a charge point, due to poor design/manufacture.