kva for a flat with all electric heating | on ElectriciansForums
Guest viewing is limited

Discuss kva for a flat with all electric heating in the UK Electrical Forum area at ElectriciansForums.net

Joined
Nov 6, 2018
Messages
10
Reaction score
0
Location
Dorset
Hi everyone

I am tearing my hair out here. I have trying to get UK Power Networks to quote for new electrical supplies in a property development I am managing. The property is a conversion into four one bed flats.

I have been asked by UKPN to provide the After Diversity Max Demand in kVA for each unit. I have asked an electrician and he said 20kVA. I asked another and he said 24 kVA.

But UKPN said this:

"UK Power Networks would in general expect the (ADMD - after diversity maximum demand) for a gas heated flat/house to be between 1.5kVA and 3.0kVA and an electric heated flat/house to be between 5kVA & 10kVA unless abnormal high usage appliances are being installed."

These units will have electric wall heaters and will be very well insulated.
They will also each have 125l unvented cylinders for water heating. They will each have an oven/grill and washing machine.

I have asked UKPN how they arrived at this figure and they pointed me to their web site (which only confuses matters and fails to show how this is calculated):

UK Power Networks - What are Watts (W), Kilowatts (kW) and Kilovolt Amps (kVA)? - https://www.ukpowernetworks.co.uk/internet/en/help-and-advice/need-help/what-are-watts.html

But on their site it says this:

" If you’re unsure and don’t tell us what you need then we would assume 15kVA but it’s important you get this right. "

I cannot seem to get them to explain. Either they are clueless or I am clueless or both.

Can anyone help?

thanks
Gus
 
I think the first figures UKPN are indicating is what they allow on their network diversity calculations. We had a 300A (maybe less) fuse go in the substation the other month and we lost a phase, it was quite suprising how many properties were covered by this fuse. 1.5-3kVA per gas property would be the figure they are applying for their network.

15kVA is the normal supply agreement where I live (15,000/230 = 65A being the maximum demanded by the loads in the property without any power factor considerations).
 
Thanks for the help.

Each flat will have the following.

3kw water cylinder
5kw elec cooker
Sockets and LED lights
Washing Machine
Fridge/Freezer
3 or 4 1.5kw to 2kw heaters.
Kettle, toaster & Microwave

I have written back to UKPN asking them to clarify how they work out kVA in the light of the difference between what they have told me and what is written on their web site.

For now I am as confused as ever.
 
UKPN said this: "UK Power Networks would in general expect the (ADMD - after diversity maximum demand) for a gas heated flat/house to be between 1.5kVA and 3.0kVA and an electric heated flat/house to be between 5kVA & 10kVA unless abnormal high usage appliances are being installed." ... I have asked UKPN how they arrived at this figure and they pointed me to their web site (which only confuses matters and fails to show how this is calculated) ... I cannot seem to get them to explain.
Hi Gus - welcome to the Forum :)
It looks like they've rounded their Design & Planning figures and fed them to you. These are likely to be a good guide for the planning of electrical distribution networks. But I think the values will be subject to the rule of averages. Some of the actual demands will be less, some will be more and the result is the table of values.

Their table seems to assume E7 to provide heating as off peak demand and that may make a big difference if your plans for heating are not off peak (?).

[ElectriciansForums.net] kva for a flat with all electric heating
 
thanks @Wilko

The flats will have normal meters (not E7 or E10) and wall mounted convector heaters.

So what should I tell them? They have said to me 5-10kVA for an electrically heated house but their web site suggests 15kVA.
 
Well if folks come home in winter and turn on 8kW of heating and put on dinner to cook while they take a shower the flat will likely draw more than 10kW for a while. The room and hot water heating are heavy loads, so I'd be asking for their max of 15kW, say a 60A fuse. Having said that, if they used 40kW for 4 flats it might not be far out as not all folks arrive home and do the same thing at the same time. Don't forget to ask for something for common areas supply.
 
Well if folks come home in winter and turn on 8kW of heating and put on dinner to cook while they take a shower the flat will likely draw more than 10kW for a while. The room and hot water heating are heavy loads, so I'd be asking for their max of 15kW, say a 60A fuse. Having said that, if they used 40kW for 4 flats it might not be far out as not all folks arrive home and do the same thing at the same time. Don't forget to ask for something for common areas supply.

thanks Wilko

It's confusing that in their emails to me they keep insisting on 5-10 but their web site says 15.
 
I made a long and careful list of all of the devices that would likely be used in each flat.
I added up the ratings of these appliances and came up with 25.85kw.

Of course, it is extremely unlikely that all of the devices would be on at the same time in each flat. However, I spoke to an electrician that did some work for me at home and he said this:

"I would definitely say 100 amp per flat and 23kva is what i worked it out at. 100 amps x 230volts divided by 1000 = 23kva per flat. yes you take in diversity but if its an all electric flat with no gas . somebody could turn dishwasher heating cooker shower on all at same time so i wouldn't want anything less than 100amp incoming fuse."

UKPN told me that there was a supply nearby which offered 69kva but that works out at 17.25kVA per flat. They said they would have to take the supply from somewhere further down the road if I wanted more.
(No prizes for guessing that will cost a lot more.)

I am not comfortable with 17.25 per flat after what my electrician and several others have suggested. Should I press for the 23kVA?

What do you guys think?
 
It's not inconceivable that we'll need charging for electric cars in the near future. There are already points on the same street. But those are public ones. Slow chargers are only about 3kw but fast ones can be 50kw and above.
 
Last edited:
Hi - with 4 flats in the block there will be a statistical reduction in max demand as not everybody does the same thing at the same time. So if heating and hot water were fully looked after at 8+3 = 11kW then their new max of 17kW sounds plausible to me. However if you want EV capability that would tip me over into spending more, as EV would likely be charging at night when folks are home with heating on, showering and cooking tea etc. Perhaps have a conversation with UKPN that you are planning to have resident EV charging and see if that changes things. Just my thoughts :) .
 
. somebody could turn dishwasher heating cooker shower on all at same time so i wouldn't want anything less than 100amp incoming fuse."

Yes someone could run round the house turning every appliance on at once, but how likely is this to happen?

With a large un vented hot water cylinder you presumably won't be having electric showers? In which case the showers won't come in to it.

Everything else will not use a constant amount of current, the thermostats will turn heating elements on and off to achieve the set temperatures so the actual power used will be a lot less than the result of adding up all of the ratings.
 
Yes indeed. There will be no electric showers. They will run on mains pressure from the tanks.
The thing is what happens if the load is exceeded? The woman told me a fuse would blow at the supply in the street.
But is that correct? Would the domestic trip flip instead?
If that's the case its not an issue.
 

Reply to kva for a flat with all electric heating in the UK Electrical Forum area at ElectriciansForums.net

Similar threads

  • Question
Gents has anyone done an application using the UKPN smart connect portal for a split phase supply and addition of multiple single phase battery...
Replies
0
Views
365
  • Question
Hello oscar21, When I wrote about cables heating up I meant that IF a cable heated up that heat could not dissipate correctly if the cable was...
2
Replies
16
Views
2K

Recommended Sponsor News

Quickwire Now Sponsor ElectriciansForums.net

I am sure you will join me in welcoming our newest sponsors of ElectriciansForums.net - Quickwire! They have decided to join us after seeing you guys discussing their products here. Now we have an expert on board that you can chat to @Quickwire-Sam who will be happy to answer your queries!

[ElectriciansForums.net] Quickwire Now Sponsor ElectriciansForums.net


@Quickwire-Sam said "At Quickwire, we're all about speed, safety, and reliability. We're a family-run business, and every Quickwire connector is proudly made right here in the UK, ensuring noticeable quality. In short, Quickwire is the fastest connection method on the market. Whether you're an experienced electrician or a DIY enthusiast, Quickwire makes electrical connections ridiculously quick and easy. We're passionate about blending British craftsmanship with innovation. If you have any questions or if there's any way we can help, please just ask me!"

Exclusive Forum Offer! Free euro 2024 wall chart for first 10 responses!

Hi everyone,

We have 10 exclusive Uheat EURO 2024 Wallcharts to giveaway for Electricians Forum Members! The first 10 people to reply YES to this thread - I will message and get them sent out to you just in time for this years tournament! GO GO GO

PCBWay Now Sponsor ElectriciansForums.net!!

I hope you will all join me in welcoming our newest sponsor to the forum PCBWay! You can contact their friendly people by sending a message to @PCBWay who will be happy to answer your queries.

Welcome to the community and thanks for your sponsorship!

[ElectriciansForums.net] PCBWay Now Sponsor ElectriciansForums.net!!

PCBWay provides services including PCB Prototype and batch Production, PCB Assembly (SMT), 3D Printing, CNC Machining, PCB Design, Electronics Modules Selling, etc. We are committed to meeting the needs of global makers from different industries in terms of quality, delivery, cost-effectiveness, and any other demanding requests in electronics.

[ElectriciansForums.net] PCBWay Now Sponsor ElectriciansForums.net!!

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
Back
Top