Design load question for my build

[Post and beam]

Good afternoon Guys

I have tried to get a price today from UK Power networks for a temp to perm electrical supply to site. They came back and asked me to provide an electricl load projection/estimate.

Does anyone have any advice on who or where i can obtain this for a building that obviously does not yet exist please.

 

keith

[Dave Jones]

depends on your build. heat pump, car charger, cooker, hob, elec shower etc all on at same time ?

 

They normally insist on 3 phase cabling anyway now although you can opt for single phase meter.

[crispy_wafer]

I'd ask for 3.ph then list out heat pump, air con, 3 ovens, hob and car chargers...  Then get octopus or your choice of electricity supplier to give you a 3ph meter.  You can still choose to use a single phase if that's how it pans out.

[Post and beam]

3ph is not relevant becuase they wanted me to pay for a new substation for the village becuase there is not enough capacity !

 

Is there a service that can provide this for a fee?

 

In a similar but different vein i paid £30 for a water usage estimate last weekend that was immediately accepted by Affinity water. Hoping there is similar for electricity and guessed this community was the likely place to find out.

[Dave Jones]

single phase is limited to the cut out fuse at 100 amps im pretty sure so just ask for that.

[Post and beam]

2 hours ago, Dave Jones said:

single phase is limited to the cut out fuse at 100 amps im pretty sure so just ask for that.

Thanks Dave. I have done a lot of reading in the past 24 hours. This is theoretically a very difficult task, Duty cycles, power factor etc. And i phoned them again to say i had prepared a list of all anticipated appliances and hours per day use.

 

But, in practice all i need to do is quote 24 KvA!!!

 

Which, as you say is a 100 amp main fuse x 240 volts.

 

 

Its easy when you know.

[Conor]

They should have a simple form that lists out types of fittings, and you simply put the wattage / amperage against each one and total it up. E.g lights 1kW, ovens, 7kW etc etc. ours came to something like 70amps with car charger.

[ProDave]

If you have limits on your local transformer and are concerned they may make you pay for an upgrade, ask them what IS available without upgrade.  In my case i was offered a 12KVA supply which has proved totally adequate.

 

More realistic appliance estimates

 

Fan oven 2kW

ALL lights on in the house at the same time 175W (all LED)

 

5kW heat pump max 2kW electricity consumption

 

Immersion heater 3kW rarely used but auutomatically soaks up surplus solar PV

 

Washing machine 3kW only when heating water, much lower at other times.

 

No bit appliances like electric showers so it is easy to see why 12KVA is enough for us.

[joe90]

With my build I had an 80 amp main fuse from my supplier, all electric with ASHP and a workshop with loads of power tools (no EV charger tho) and this is adequate.

[Post and beam]

21 minutes ago, ProDave said:

If you have limits on your local transformer and are concerned they may make you pay for an upgrade

There is no concern for 1ph. But when surveyed i was told that its only about £150 more for a 3ph supply. So i said yep lets go for that then.

Then i got a phone call saying 'no capacity in the village for 3ph you can pay for a new sub station.'

 

Single phase it is then.

[Post and beam]

Update:

It appears there is an issue with 1ph.

There is not enough power in the sub station even for 23kVA so they expect me to pay for an upgraded sub station regardless. I was told this afternoon that my house would account for 25% of the total capacity of said sub station. Even though there are 33 existing houses sharing the current supply. I find this difficult to understand.

I have asked them to price up anyway and see how bad this is going to get. I will also ask them what i could get without upgrading.

Ground solar array on the Horizon?

[JohnMo]

14 minutes ago, Post and beam said:

my house would account for 25% of the total capacity of said sub station

Do you have a typo on the application?

[ProDave]

1 hour ago, JohnMo said:

Do you have a typo on the application?

+1  Something does not sound right at all.

[Post and beam]

Application is only verbal.

I asked for a supply, they told me to give them a kVA estimate which i did. They said there is not enough and then quantified it as i described.

[ProDave]

11 minutes ago, Post and beam said:

Application is only verbal.

Get a formal application in. Then you will get a grown up on the job who knows what they are talking about. 

[Post and beam]

2 hours ago, ProDave said:

Get a formal application in.

My telling them my projected load is the route to a formal application, it has been passed to the team to survey and price. Time will tell

[Kelvin]

5 hours ago, Post and beam said:

Update:

It appears there is an issue with 1ph.

There is not enough power in the sub station even for 23kVA so they expect me to pay for an upgraded sub station regardless. I was told this afternoon that my house would account for 25% of the total capacity of said sub station. Even though there are 33 existing houses sharing the current supply. I find this difficult to understand.

I have asked them to price up anyway and see how bad this is going to get. I will also ask them what i could get without upgrading.

Ground solar array on the Horizon?

You can’t be accounting for 25% of a substation that has 33 houses on it. It’s not difficult to understand it’s impossible and the DNO should be able to see that. You only get any sense out the DNO when you make a formal application because they then have to do the correct survey/design work rather the desktop stuff that produces a load of nonsense. 

[Post and beam]

8 hours ago, Kelvin said:

You can’t be accounting for 25% of a substation that has 33 houses on it.

I know.

8 hours ago, Kelvin said:

It’s not difficult to understand it’s impossible

I know

8 hours ago, Kelvin said:

when you make a formal application

I have

Time will tell

[Post and beam]

Update:

I have my formal application in and took a phone call yesterday from a nice young woman.  Apparently the 33 other houses on this village sub station share 100kVA. My application for 23kVA ( 24 is into 3ph territory apparently) is indeed 25% of the total as far as they are still insisting ! so they wondered if 5kVA might be enough.

Yep, i choked on my coffee as well!!!

 

Of course 75 kVA divided by 33 = 2.27 amps.  So far i cannot get anyone there to read their own crap and realise this makes no sense.

[garrymartin]

In years gone by... 😉 3 kW per house as peak load in a village might have been fine, given not everyone will use 3 kW at the same time, but there is no way that sort of capacity is going to support a move to more extensive use of electric vehicle chargers, renewables and low-carbon technologies such as ASHP/GSHP, and the supply company should certainly know that - i.e. at some point they will have to put network reinforcements in place.

 

Stand your ground on your supply requirements if you have a robust case and remind them that it is their responsibility to reinforce the network to support those requirements.

[ProDave]

We have 8 houses sharing a 100KVA transformer which is where they derived the 12KVA that they offered me with no upgrade charges.  They don't seem to apply diversity.  What surprised me was when installed it was the same size cable as they would use for a 21KVA supply and they fitted a 100A fuse.

 

You could ask what fuse they would fit in the supply head if you accepted a "3KVA" supply?  I think the smallest would be 40A which would amount to 9KVA

 

But with that many houses on one 100KVA transformer it does sound like it is time they upgraded it, and it still looks like they are trying to get you to foot part of the bill for that.

[Alan Ambrose]

I thought it was clear these days that the DNOs couldn’t make you pay for building their own infrastructure - only your own connection. Did I slip into a parallel universe for a bit?

[Post and beam]

On 04/07/2024 at 13:51, ProDave said:

But with that many houses on one 100KVA transformer it does sound like it is time they upgraded it, and it still looks like they are trying to get you to foot part of the bill for that.

Thats my suspicion in a nutshell. 

On 04/07/2024 at 19:05, Alan Ambrose said:

I thought it was clear these days that the DNOs couldn’t make you pay for building their own infrastructure - only your own connection.

Thats my understanding. The worry i have with both of these comments though is the size of the invoice they want to present me with. I wonder if their ' % contribution' figure is open to scrutiny. If not, its a bit academic because it can be whatever they want to make it.

I am not committed to anything at this point which is why i asked them to proceed on the 23kVA basis. If the cost is too high i can revise my request.

 

[Alan Ambrose]

Have a £K quote yet?

[Post and beam]

23 minutes ago, Alan Ambrose said:

Have a £K quote yet?

No