Green Building Forum - 3 phase electrics

3 phase electrics

Artiglio — Tue, 16 Jan 2024 14:28:52 +0000

Good day all

My mother is currently in the process of selling her rural home that has a 3 phase ( late father had workshops in outbuildings) they’d paid for the supply in the 90’s.
They then had 3 individual meters and were billed as 3 accounts/supplies. A query from a potential buyers solicitors is why don’t we have a 3 phase meter and so only have a single rather than 3 standing charges.
This is not something i have any clue of , could anyone advise what the normal arrangement would be?

TIA

3 phase electrics

djh — Tue, 16 Jan 2024 16:52:27 +0000

Posted By: ArtiglioMy mother is currently in the process of selling her rural home that has a 3 phase ( late father had workshops in outbuildings) they’d paid for the supply in the 90’s.
They then had 3 individual meters and were billed as 3 accounts/supplies. A query from a potential buyers solicitors is why don’t we have a 3 phase meter and so only have a single rather than 3 standing charges.
This is not something i have any clue of , could anyone advise what the normal arrangement would be?

Pure guesswork on my part but maybe they had a single phase supply to the house and three-phase supply to the workshop, so the phases would be unbalanced and need separate billing? Hopefully somebody who actually knows will be along in a minute!

I'd have thought a bland reply to the potential purchaser along the lines of "the arrangement suited the present owners; new owners may wish to change the supply arrangements to suit themselves" would be enough.

3 phase electrics

revor — Tue, 16 Jan 2024 17:00:31 +0000

I have 3 phase to our outbuildings. There are 3 meters and I have one bill monthly based on readings I have supplied
There is only one standing charge. It is odd that you do not have this arrangement. I had new digital meters installed a few years ago (not smart) and was offered one meter but I preferred to have all phases metered as each phase can be linked to the activity on that phase. I think the previous owner had this arrangement as he let out part of the building and could charge electricity to the tenant on that phase. You do not say if your meters are smart not sure if that would make a difference. My outbuildings are on a business tariff I have separate smart meter for the house which is single phase and is billed as domestic. I am with Octopus they may be different to your supplier but I had my current arrangement with previous energy suppliers.

3 phase electrics

Artiglio — Tue, 16 Jan 2024 18:43:42 +0000

There is just the 3 phase supply with each phase metred, after the meters the supplies are distributed, so house , or workshops as required, only the two main workshops get 3 phase.
Not smart meters, apparently mobile signal in the area isn’t good enough ( despite us getting 20mb plus on mobile broadband). The bills come as 3 seperate accounts one for each phase with a standing charge for each. These days with workshops unused the standing charge is a significant portion of the total bill.
Currently our response is “you have copies of the bills, any queries should be directed to the supplier”

3 phase electrics

Peter_in_Hungary — Tue, 16 Jan 2024 19:18:10 +0000

The provision of 3 single phase meters or 1 x 3 ph. meter would need to be discussed with the supplier. Don't assume that the standing charge for a 3 ph meter will be the same as for a 1 ph meter, you may well find that there is a (significant) difference.

phases don't need to be balanced and usually aren't (to the annoyance of the suppliers) because too many things only use 1 ph.

You don't need separate supplier meters to provide separate billing to tenants and alike. I have my own sub meter down stream of the suppliers meter to give billing.

Edit to add
Over here if you want any change to your meter(s) or main fuse then the whole consumer unit needs to be brought up to current standards which can be an expensive exercise (500 quid when I did one 2 years ago). So check that out before going too far down the road of changes.

3 phase electrics

djh — Tue, 16 Jan 2024 20:47:03 +0000

Posted By: Peter_in_HungaryOver here if you want any change to your meter(s) or main fuse then the whole consumer unit needs to be brought up to current standards which can be an expensive exercise (500 quid when I did one 2 years ago). So check that out before going too far down the road of changes.

Meters and consumer units are completely separate here. Meters are installed by and looked after by the supplier (or a sub-contractor). CU are installed and looked after by the owner and/or a domestic electrician. Never the twain shall meet! Leads to some interesting arguments when first installing new circuits about who does what and when (don't ask me how I know this).

3 phase electrics

cjard — Sat, 27 Jan 2024 18:33:26 +0000

Because doing it as 3 phase metred might have seen them ending up with a commercial/business grade supply contract at some eyewatering cost?

3 phase electrics

philedge — Mon, 29 Jan 2024 08:16:42 +0000

Just a guess, but maybe your dad wanted the house metered and billed separately from the workshops and the only way to do it, at the time, was to have three separate single phase supplies? Maybe standing charges were much lower in the 90s and the extra cost for 3 separate supplies wasn't an issue?

3 phase electrics

Artiglio — Mon, 29 Jan 2024 09:24:24 +0000

Cheers Gents, all perfectly feasible suggestions, though given all the various oddities that are turning up in paperwork , i’d guess the easiest / proferred option at the time was the way most things were sealt with. Not really an issue now as the buyer has pulled out after 5 months.

( claimed they were going overseas to work, but companies house show they’d set up another company , which links to another property purchase elsewhere, so back to square 1)

3 phase electrics

Jeff B — Wed, 31 Jan 2024 19:55:41 +0000

I may be totally naive here but why not simply have the 3 phase removed and single phase installed? I guess there must be a snag otherwise someone who is more au fait with this subject than me!

3 phase electrics

Jeff B — Wed, 31 Jan 2024 19:58:42 +0000

Sorry, last sentence should read: otherwise someone who is more au fait with this subject than me would have already suggested this!

P.S. Have just upgraded to Windows 10 and am getting the "unsafe site" messages that others have had and autofill is switched off. Cannot edit or quote anymore.

3 phase electrics

Mike1 — Wed, 31 Jan 2024 20:54:03 +0000

Posted By: Jeff BP.S. Have just upgraded to Windows 10 and am getting the "unsafe site" messages that others have had and autofill is switched off. Cannot edit or quote anymore.

It's not a Windows 10 problem, it's almost certainly a problem with your browser - at least Chromium based browsers (including Microsoft Edge) - that now consider any website with a http:// URL an unacceptable security risk. While it's true that it's possible to more easily intercept http traffic (and very much harder / impossible to do so with https traffic), the risk and consequences are low with a site such as this (compared to an online shop, for example).

I'm running Windows 10 Pro and have zero issues with this site when using Pale Moon browser, which retains a saner traditional security policy. https://www.palemoon.org/

3 phase electrics

Artiglio — Wed, 31 Jan 2024 23:00:07 +0000

Hi JeffB

The workshops have 3 phase supplies ( from when my father had his woodwork business) , plus the house is currently on one phase, a couple of outside guest rooms on another and the workshops each have all three. If a future owner wanted to change all that then they could, but it gives more options for use keeping it whilst on the market. Plus i expect changing it all onto one phase would entail a fair bit of work and flag up a need to meet current regs on some parts.
Also there’s a SSW facing roof that could accomodate a lot of solar panels and assuming you could have 4kw for each phase it offers more options for a future owner.

3 phase electrics

philedge — Thu, 01 Feb 2024 16:36:47 +0000

Definitely keep the 3 phase. With a main house, 2 electrically separate guest rooms and workshops you'd likely struggle with a single phase. Add in a future heat pump(s) and EV charger(s) and you'll almost certainly need 3 phase, or a future owner will

3 phase electrics

Peter_in_Hungary — Thu, 01 Feb 2024 17:19:59 +0000

Posted By: philedgeDefinitely keep the 3 phase. With a main house, 2 electrically separate guest rooms and workshops you'd likely struggle with a single phase. Add in a future heat pump(s) and EV charger(s) and you'll almost certainly need 3 phase, or a future owner will

Wot philedge said +1

3 phase electrics

chrisinbrighton — Thu, 01 Feb 2024 17:39:41 +0000

A plumber told me recently he thought all houses would need 3 phase

3 phase electrics

djh — Thu, 01 Feb 2024 21:12:11 +0000

Posted By: chrisinbrightonA plumber told me recently he thought all houses would need 3 phase

Our house is all electric including an EV and we're nowhere near the 100 A, (max is 40-50 A so far) so I have to wonder why the plumber said it. We use direct electric heating overnight and I charge the car then as well. The only thing we don't do at night is cooking.

3 phase electrics

Jeff B — Thu, 01 Feb 2024 23:13:58 +0000

Posted By: Mike1
Posted By: Jeff BP.S. Have just upgraded to Windows 10 and am getting the "unsafe site" messages that others have had and autofill is switched off. Cannot edit or quote anymore.
It's not a Windows 10 problem, it's almost certainly a problem with your browser - at least Chromium based browsers (including Microsoft Edge) - that now consider any website with a http:// URL an unacceptable security risk. While it's true that it's possible to more easily intercept http traffic (and very much harder / impossible to do so with https traffic), the risk and consequences are low with a site such as this (compared to an online shop, for example).

I'm running Windows 10 Pro and have zero issues with this site when using Pale Moon browser, which retains a saner traditional security policy. https://www.palemoon.org/

Mike - you were right. When I upgraded to Windows 10 I also had the old HDD removed and an SSD hard drive* installed. I always used Firefox before and had no trouble with the GBF so I have reinstalled Firefox and everything is back to normal!

*The difference in speed is incredible now. My desktop boots up in seconds, before it was many minutes. In fact I would turn the PC on and go and make a cup of coffee whilst waiting for it to boot up!

3 phase electrics

Jeff B — Thu, 01 Feb 2024 23:17:30 +0000

Posted By: ArtiglioHi JeffB

The workshops have 3 phase supplies ( from when my father had his woodwork business) , plus the house is currently on one phase, a couple of outside guest rooms on another and the workshops each have all three. If a future owner wanted to change all that then they could, but it gives more options for use keeping it whilst on the market. Plus i expect changing it all onto one phase would entail a fair bit of work and flag up a need to meet current regs on some parts.
Also there’s a SSW facing roof that could accomodate a lot of solar panels and assuming you could have 4kw for each phase it offers more options for a future owner.

Fair enough, you make some good points there. Just wonder how a prospective buyer would take to the thought of having three lots of standing charges though?

3 phase electrics

WillInAberdeen — Fri, 02 Feb 2024 08:37:55 +0000

The standard fuse in a house cutout is moving to 80A (even if the fuse holder has a 100A rating marked on the outside).

But cutout fuses are specified to be slow acting, the 80A fuses are suitable for 100A for several hours or 150A for half an hour.

That's plenty for a heatpump, EV charger, cooker, freezer, lights, kettle and toaster. Plenty of people have tried this with data loggers and they don't all fire at the same instant so the total current turns out less than you would expect from just adding up all the loads.

The difficulty might be voltage losses on the distribution company's side, they might not be able to supply higher current to everyone in the street all at once, while still keeping the legal voltage. Historically they pushed up the voltage at the transformer to the top of the legal range, to stay within range at the customers. But now people also want to export from PV/battery/V2G and don't want high voltages that trip their inverters.

So if you already have a 3 phase supply - hang onto it!

3 phase electrics

Peter_in_Hungary — Fri, 02 Feb 2024 09:19:09 +0000

Posted By: WillInAberdeenThat's plenty for a heatpump, EV charger, cooker, freezer, lights, kettle and toaster. Plenty of people have tried this with data loggers and they don't all fire at the same instant so the total current turns out less than you would expect from just adding up all the loads.

You are right about diversification within a house meaning the chances of everything firing up at once are v.low but with single phase I've not seen a charger bigger than 7kW, a 3 ph supply gives the option of a 22kW charger. With my EV which I don't let go much lower than 20% takes a bit in excess of 12 hours to get to 80% with a 1 ph charger. That is why 3 ph will be wanted by many going for EVs (my 3 ph charger is waiting installation)

3 phase electrics

Artiglio — Fri, 02 Feb 2024 11:56:55 +0000

Jeff, obviously that particular potential purchaser or their solicitor felt it was a bit of an issue, but that’s what enquiries and negotiation is all about, personally my feeling is it’d be madness to get rid of the 3 phase as lord knows what it would cost in terms of rewiring to go to a single phase and future reistateemnt if ever needed, even if it isn’t possible to get round the 3 lots of standing charge , i’d be pretty sure that there would be a myriad of other things that could be changed to save more money, seemed an odd thing to focus on. The flexibility the 3 phase offers to my mind is worth way more than the additional standing charge.

As an aside - the lack of fibre broadband has been the single most common negative raised by those that have viewed, people aren’t interested in other solutions, fibre is the only solution they want. So we’ve paid just over £8k for a fibre connection (some works have commenced but no date as yet for actual connection) which is galling as the fibre runs down the road already and serves the school up the road one way and the village the other. Alledgedly there is no spare capacity in the existing fibre and we need new fibre run from the exchange which is over 5 miles away. I’m reliably told from those working in the industry that it’s inconceivable ( due to future connection obligations) that there is not spare fibre in the ducts , but there’s no way we can prove it.

3 phase electrics

Peter_in_Hungary — Fri, 02 Feb 2024 12:44:02 +0000

Posted By: ArtiglioI’m reliably told from those working in the industry that it’s inconceivable ( due to future connection obligations) that there is not spare fibre in the ducts , but there’s no way we can prove it.

Yes but they can't possible use it because it may be needed (in the future).

If I was the provider I would be keeping any reserve for obligatory provision for which they they couldn't charge full price.

3 phase electrics

WillInAberdeen — Sat, 03 Feb 2024 09:42:09 +0000

Peter, out of interest, can your car accept charge at 22kW AC?

UK spec cars can charge at 7.2kW on single phase AC or 11kW on 3ph, if the chargepoint can supply it. There is not enough benefit going from 7.2 to 11kW, to justify installing 3-phase at home afaics.

There are a few UK-market cars that can charge at AC 22kW - Zoe is one. Higher power chargers than that are DC.

A couple of 8-hour charges a week at 3.6kW gives 200 miles, enough for most folk, or a 7.2kW charger shrinks that into 4-hour cheap slots.

Just looking at my options!

3 phase electrics

Peter_in_Hungary — Sat, 03 Feb 2024 11:16:26 +0000

Posted By: WillInAberdeenPeter, out of interest, can your car accept charge at 22kW AC?

No.
11kW for an AC charger. 77kW for DC (KIA Niro EV)
11kW is 3 ph. I had 3 ph before the car. It was needed to get the required amount of PV that I wanted to be neutral grid use when going to a heat pump.

SWIMBO wanted a new car (pi##ed of with a 26 year old Land Rover) so we have the car and no HP. when the HP gets done then more PV will be installed.

The 11kW charger will be useful (when it gets installed) 'cos I will get better top up times and when I come home a bit late I can will get a charge up by 8 am the next day.

Over here the standard 1 PH supply is 32A with 'cost a lot' to get more. The suppliers don't like giving more than 32A/PH. I have 3 x 32A

From what I see the trend is for EVs to have faster charge rates - which means more A. My charger will do 22kW but it is capped by the cars magic.

3 phase electrics

djh — Sat, 03 Feb 2024 13:38:56 +0000

Posted By: Peter_in_HungaryWith my EV which I don't let go much lower than 20% takes a bit in excess of 12 hours to get to 80% with a 1 ph charger.

Have I done something wrong in my sums?

The Kia Niro EV has a 64.8 kWh battery (I have an e-Niro with a 64 kWh battery :) so 20% to 80% is 60% is 38.88 kWh. At 12 hours that's 3.24 kW. Which implies you're using a granny charger. Using a 'full strength' single phase charger at 7.3 kW it only takes 5.4 hours for that charge. So I think it's a bit disingenuous to say that 3-phase is necessary. I think it's more likely that your worry is caused by your low 32 A limit.

Your 3-phase supply is approximately the same as my 100 A single phase. (and no it's not 80 A).

3 phase electrics

Peter_in_Hungary — Sat, 03 Feb 2024 19:34:27 +0000

Posted By: djhWhich implies you're using a granny charger.

Yes a granny charger, plugs into a 16A socket.
The 3 PH charger will be 3 x 16A

Posted By: djhYour 3-phase supply is approximately the same as my 100 A single phase.

Except I can't run a standard electric hob although a current limited hob would work and I need to be careful to distribute the loads across the phases and be careful where they go (e.g.I don't want 2 phases next to each other in the kitchen)

3 x 32 is not as convenient as 1 x 100. There is 3 x more wastage at the top end of the limit.

3 phase electrics

djh — Sat, 03 Feb 2024 20:04:53 +0000

Posted By: Peter_in_HungaryExcept I can't run a standard electric hob although a current limited hob would work and I need to be careful to distribute the loads across the phases and be careful where they go (e.g.I don't want 2 phases next to each other in the kitchen)

Ah yes. Our hob is 40 A IIRC. A friend has a 13 A one that she seems happy enough with. But if your supply is common there I'm surprised there aren't three phase hobs? It would seem easy enough to feed some of the hotplates from one phase and others from another; it's the total load of the hob that's high rather than the individual hotplates.

And yes, I agree that a single phase is easier to manage in lots of ways.

edit to add: I was once helping to abuse a three-phase installation in my student days and we were mightily confused before we discovered that what was labelled blue phase on the fuse box emerged elsewhere as red phase (or some similar misnaming). :(

3 phase electrics

revor — Sun, 04 Feb 2024 08:56:00 +0000

Posted By: djhBut if your supply is common there I'm surprised there aren't three phase hobs?

There are 3 phase hobs. Our hob can be wired as 3 P as well as 1P It was very confusing when I first read the instructions.

Posted By: djhedit to add: I was once helping to abuse a three-phase installation in my student days and we were mightily confused before we discovered that what was labelled blue phase on the fuse box emerged elsewhere as red phase (or some similar misnaming). :(

Having 3P I understand can be dangerous if you happen to mix phases by inappropriate use of extension leads or modify wiring in any way.

3 phase electrics

revor — Sun, 04 Feb 2024 09:46:44 +0000

appended diagram NEF ind hob