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Power supply issue pre home charger install

Caterman

Member
Nov 13, 2020
71
33
Birmingham
In the run up to getting my car I've got 3 quotes dating back to October, got the car yesterday and got a call today from a very nice lady from Western power Distribution advising me that they had been contacted by one of the fitters who quoted and my power supply is not fit for a home charger.
Apparently I am on a looped supply so I share the supply with my next door neighbour and a street light and I will need a new supply cable fitted which will be free but involves digging up a chunk of our road and more importantly a trench across our drive.
I thought I had researched home charging thoroughly but I had never heard of this , is it common?
House is on an estate built about 30 years ago
Wonder if they would fit 3 phase while they are at it :) Has to be some silver lining to this surely.
 

ACarneiro

Active Member
Jun 20, 2019
1,304
1,030
Shrewsbury, Shropshire, UK
It’s not common but certainly not a rarity. Good thing they’re unlooping for free, I believe some people have been quoted thousands for the works.
Worth asking about 3ph supply although you’ll probably need a new meter box to conform to regulations and a sparky to do the required wiring in the house (whether to split the loads across phases or keep the whole house in one phase).
 
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26ct2143

Member
Nov 22, 2020
181
74
Burton-on-Trent, UK
In the run up to getting my car I've got 3 quotes dating back to October, got the car yesterday and got a call today from a very nice lady from Western power Distribution advising me that they had been contacted by one of the fitters who quoted and my power supply is not fit for a home charger.
Apparently I am on a looped supply so I share the supply with my next door neighbour and a street light and I will need a new supply cable fitted which will be free but involves digging up a chunk of our road and more importantly a trench across our drive.
I thought I had researched home charging thoroughly but I had never heard of this , is it common?
House is on an estate built about 30 years ago
Wonder if they would fit 3 phase while they are at it :) Has to be some silver lining to this surely.
Never heard of that before.
If it's a free upgrade, bite their arm off!
If 3 phase a possibility, that would be nice ay, although you'll need a new meter for 3 phase, and some changes to your consumer unit, unless you keep the house single phase and run the extra 2 phases around and into the charger. I don't know the regs regarding this kinda a thing, but might be possible?
 
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Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,704
UK
Yes, as above, there are still some looped supplies around. I believe there may now be an obligation on DNOs to unloop supplies for free for EV charge point installations, but as you've found, the work involved can be extensive.

Looped supplies were a cost saving dodge used by some house builders years ago, usually in terraced or semi-detached properties, as doing this avoided the need to run separate supplies to every house. They've always been a PITA, for several reasons, not just the low maximum allowable load (often only 60 A, or even 40 A).
 

Caterman

Member
Nov 13, 2020
71
33
Birmingham
John, thanks for the video, that's pretty much what I'm expecting. Until the WPD engineer comes round I'm not clear what the impact to my neighbours property is as well.
We have a tarmac drive so there is no way that they will be able to match the existing tarmac.
Had WPD phoned me a week ago I would probably have cancelled the car. This EV business is proving a lot more hassle and cost than I expected. My charger quote was done about 2 months ago (approx £1k because I want the charger in the garage rather than next to the meter cupboard) why it has taken that long to advise me of the issue I don't know and if I need to get the drive redone post trench ....
The 3 phase comment was a bit tongue in cheek, I know it's more hassle than its worth for a domestic property.
 

26ct2143

Member
Nov 22, 2020
181
74
Burton-on-Trent, UK
The 3 phase comment was a bit tongue in cheek, I know it's more hassle than its worth for a domestic property.
When we lay a supply to a new area of a building, we always lay 3 phase just because the cable isn't much bigger or more costly (the main cost is doing the job), but the other 2 phases are there incase we want them. Even if we only connect 1 phase at the end.
But I get where your coming from.
Single phase houses generally seems to be a UK thing. In France a lot are 3 phase.
 

MOBB

Member
Sep 18, 2019
161
123
Bedfordshire
May be a daft question, but do you definitely need a home charger?

I used the 3 pin charger initially as I was about to move house, and with my mileage I could have got away without a charger with hindsight
 
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ACarneiro

Active Member
Jun 20, 2019
1,304
1,030
Shrewsbury, Shropshire, UK
Once heating starts going electric (heat pump set al), 100A single phase may not be enough. You may also find that future cars may have 100 or maybe even 200kWh batteries and the current supply is no longer adequate. Who knows?
I would definitely have 3ph installed if the cost increase was negligible.
Future proofing never hurt anyone.
 

rincewind

Member
Nov 5, 2019
528
291
London England
You may also find that future cars may have 100 or maybe even 200kWh batteries and the current supply is no longer adequate.

It's more about the amount of charge you need on a per day basis, not the size of the battery e.g. if you only drive 50 miles then a couple of hours charging at 7kwph is fine. Even if you get home from a trip of 300 miles, that will still be replenished in about 10 hours charging.
 
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ACarneiro

Active Member
Jun 20, 2019
1,304
1,030
Shrewsbury, Shropshire, UK
But future cars may be less frugal?
There are current design compromises related to the battery low energy density which may no longer hold true if and when that doubles, so consumption may well go up and your 50 mile commute might use a lot more juice?
Unlikely, granted, but the point is that you don’t know the future and mitigating against those possibilities is easy and cheap now and will certainly not be if you have to dig up the drive again in 10 years time.
 

Durzel

Active Member
Jul 17, 2019
3,072
2,089
Bath, UK
If 3 phase is an option and not much more expensive I’d go for that myself, even if you don’t use it now. Unless of course you don’t cover think where you’re living to be a “forever home”.

Since you’re going to have to have your drive dug up to fix the looped supply (for free) the lion share of the work involved in installing 3 phase is already being done.
 

Caterman

Member
Nov 13, 2020
71
33
Birmingham
MOBB I don't really need the home charger at the moment, hence why I was quite relaxed about getting it fitted , however once work gets back to normal it won't be too uncommon to get home late on 20% and need it to be ready for a 300 mile trip by 5 am.
There is also the issue of maximising my cheaper Octopus Go tarriff, if I can do most of my charging between 0.30 and 4.30 am it is a third of the normal tarrif ( I do accept that i'll have to do a lot of that to repay the cost of the charger :) )
 
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BigWig20

Member
Jul 4, 2020
16
16
Sussex, Uk
Hello

I had the same issue with a looped supply shared with my neighbour. The electrician who fitted my Tesla charger in the garage, registered the install and the Uk power network man then came round and upped the main fuse. Not had any problems charging overnight on Octopus Go at 7Kw. But then nothing else is using the supply at night. Garage is on a separate fuse board from the house.
 

Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,704
UK
Once heating starts going electric (heat pump set al), 100A single phase may not be enough. You may also find that future cars may have 100 or maybe even 200kWh batteries and the current supply is no longer adequate. Who knows?
I would definitely have 3ph installed if the cost increase was negligible.
Future proofing never hurt anyone.

Whilst I agree about future proofing, electric heating is surprisingly low power. For example, we have a 6kW heat pump that runs our central heating. Its maximum current from the grid, when running flat out, is 9 A. That's lower than a kettle. We don't need anything like 6 kW for heating, either, even during this cold spell our heat pumps hasn't yet exceeded 4 A input, equivalent to about 2.7 kW heat output, and even then it's only been on overnight for a few hours.

OK, our house is well-insulated, air-tight and has heat recovery ventilation, but we keep it at around 22.5°C downstairs, around 19°C upstairs. Even our old house, a 1980s bungalow, with little insulation, and double glazing that wasn't great, only needed around three times the heat input of this house, so would probably manage with a heat pump drawing maybe 12 A in very cold weather. That's about the same as an immersion heater.

That's the really big advantage of heat pumps, if properly sized, installed and set up they deliver around three times the heat output for a given electrical power input. I keep track of ours, and it varies from about 3.5 times the heat output to over 4 times the heat output compared to the electrical input, so barely costs more to run than a gas boiler, especially as most of the time it runs overnight during the cheap rate period. Even in this really cold weather we're only paying about 3p/kWh for central heating.
 

RedMod3

Member
Oct 21, 2020
107
68
Hampshire, UK
Interesting story. We have air-sourced heat pumps (7.5kW and 5kW) and with temperatures around 1C outside, they are not giving the 3:1 or 4:1 efficiency ratio we get is less cold weather.

However, we went from storage heaters to the heat pumps with a huge drop in electricity consumption. The Tesla charger we have is only used at night and 7kW is not that much, and less that what the storage heaters used.
 

Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,704
UK
I spent ages tuning the set up of our main heat pump, the one that heats up the underfloor heating. As it was delivered, it was set up for a relatively dry climate, and the guidance from the manufacturer on the effect of the settings, particularly those that effect the defrost cycling, wasn't great. After a lot of trial and error, and much measurement of heat output versus electrical power input, I ended up turning off the weather compensation (the biggest single hit on efficiency - it's the exact opposite of what's actually needed) and finding that setting a fixed flow temperature of 40 deg C gave far and away the bet performance. In very cold weather the CoP drops to about 3.8, in cool, damp, weather (around 4 deg C and wet seems the worst) the CoP drops to about 3.5, and in dry, relatively mild weather, the CoP rises above 4.

Compared to the "as delivered" performance there's a big difference. As delivered, the thing struggled to get a CoP of 2.5 in cool, damp, weather, and barely managed a CoP of 3 in cold, dry, weather. I get the feeling that few installers have a clue as to how best to set the unit parameters for best efficiency.
 
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