New Home Charger Installations & DNO EV Applications

[LEE3]

So I had a charger installed at home a few weeks ago and the electrician had recently been on ‘the course’ where he learned that anyone that has a maximum electrical demand in excess of 60 amps has to effectively apply to the ENA for approval to use the charger so that the supply / capacity can be appropriately assessed.

ENA - Electric Vehicles and Heat Pumps

He went round and switched all the main appliances on in the house which reached around 50 amps and this was obviously without the car charging as it was yet to arrive. So he then suggested that as the car charging will nudge the output over 60 amps I would need to submit the form.

Since then I have purchased an energy monitor and even with the car charging I cannot make this thing reach anywhere near the 60 amp mark. On average so far it’s maybe 30 amps.

Now of course I could go round switching on two ovens two kettles two tumble dryers all the lights and the car but the reality is that is not normal usage. So I am hesitant to engage with UK power networks at this stage and have the usual painful dealings with them (big previous issue with relocating mains cables costing £10000+) when I can effectively manage my output to never reach this 60 amp limit. My concern is Power Networks will use the opportunity to make upgrades to the substation and try to charge me for it. (Private road with old infrastructure recently taken over by Power Networks).

So is there anyone else who has made this application with any complications?

 

[kevuwk]

So I had a charger installed at home a few weeks ago and the electrician had recently been on ‘the course’ where he learned that anyone that has a maximum electrical demand in excess of 60 amps has to effectively apply to the ENA for approval to use the charger so that the supply / capacity can be appropriately assessed.

ENA - Electric Vehicles and Heat Pumps

He went round and switched all the main appliances on in the house which reached around 50 amps and this was obviously without the car charging as it was yet to arrive. So he then suggested that as the car charging will nudge the output over 60 amps I would need to submit the form.

Since then I have purchased an energy monitor and even with the car charging I cannot make this thing reach anywhere near the 60 amp mark. On average so far it’s maybe 30 amps.

Now of course I could go round switching on two ovens two kettles two tumble dryers all the lights and the car but the reality is that is not normal usage. So I am hesitant to engage with UK power networks at this stage and have the usual painful dealings with them (big previous issue with relocating mains cables costing £10000+) when I can effectively manage my output to never reach this 60 amp limit. My concern is Power Networks will use the opportunity to make upgrades to the substation and try to charge me for it. (Private road with old infrastructure recently taken over by Power Networks).

So is there anyone else who has made this application with any complications?

I’m currently talking to my DNO and they say I can get an 80a fuse free of charge if it is for EV charging. If you think you need the 80a then it may be worth enquiring but the 100a fuse usually requires some wiring and fuse holder upgrades

 

[NorfolkMustard]

Yeah, it’ll probably just be a fuse swap in the incommer, get them to install an isolator switch while they’re there to make it worthwhile if they do charge.

 

[MrBadger]

Is the 60A limit because you have a 60A fuse or will it also apply to those with 80A and 100A fuses?

Is the 60A limit based upon the diversity calculation?

I've got a 100A fuse and can show my max load during the day as I log it on 5 minute basis 24/7/365

 

[LEE3]

I have an 100 amp fuse. Does this make any difference as I thought it’s the providers desire to be told of demands on the network rather than the capacity at the house?

 

[NorfolkMustard]

Hadn’t heard that. If that were the case you think they’d have fitted 60amp main fuses so they have to be involved in increases, rather than relying on being notified.

 

[interbear]

I’m currently talking to my DNO and they say I can get an 80a fuse free of charge if it is for EV charging. If you think you need the 80a then it may be worth enquiring but the 100a fuse usually requires some wiring and fuse holder upgrades

I was told exactly the same by Western Power when I enquired. They swapped out the existing 60a fuse for a 80a fuse free of charge and told me that it would be more than enough for our household + the EV charger. A 100a fuse would have required (1) Western Power to change the fuse holder, estimate at £150ish and (2) the electricity supplier to upgrade the meter tails (cables) from 16mm to 25mm, which is apparently needed for a 100a fuse. I actually had EDF do the latter anyway (it was free) just in case I need to upgrade to a 100a fuse in future. Which I doubt will be necessary.

 

[kevuwk]

I was told exactly the same by Western Power when I enquired. They swapped out the existing 60a fuse for a 80a fuse free of charge and told me that it would be more than enough for our household + the EV charger. A 100a fuse would have required (1) Western Power to change the fuse holder, estimate at £150ish and (2) the electricity supplier to upgrade the meter tails (cables) from 16mm to 25mm, which is apparently needed for a 100a fuse. I actually had EDF do the latter anyway (it was free) just in case I need to upgrade to a 100a fuse in future. Which I doubt will be necessary.

I wasn't sure what fuse I had and neither did they. One of their engineers has just been and checked and there is a 100a fuse so I can finally start looking at getting a charging point installed.

 

[LEE3]

So the results of communicating with the DNO appears to relate more to the capacity of the premises and not their own infrastructure.

 

[Fullerene]

He went round and switched all the main appliances on in the house which reached around 50 amps

Now of course I could go round switching on two ovens two kettles two tumble dryers all the lights and the car but the reality is that is not normal usage.

This is ridiculous and unrepresentative. I have lots of sockets in my house, I've got 3 large Distribution boxes in the garage and a further one in the shed, previous owner was trying to future proof or something... If I put a 3kW heater on each socket the load would be ridiculous - but on a very rare occasion my worst case is oven & dishwasher & kettle. which is about 7-8 kW, I can accurately count the amount of times this has happened in the past few years on one hand, I have a home rolled energy monitor and graph this sort of thing to death.

So the results of communicating with the DNO appears to relate more to the capacity of the premises and not their own infrastructure.

As far as I know the DNO needs to be informed as it's their duty to have adequate infrastructure, part of which is paid by a levy from all of our electricity bills.

What staggers me is choosing the car is really simple, choosing the EVSE was the hardest part.

 

[MrBadger]

I looked in the document posted and the calculation can be done on known usage (I think it is total usage rather than individual loads) or using a diversity calculation. So going around and turning everything on and measuring the output is probably not the most sympathetic method to do it.

I have 5 minute load readings going back quite a few years which would hopefully satisfy the final paragraph.

8. What is Maximum Demand (MD)?
The Maximum Demand of a circuit, property, section of network, or network that considers that all loads associated with that network will not be drawn at the same time.

9. How do I calculate the MD of a premises?
There is guidance in the IET Code of Practice for EV Charging Equipment Installation on supply adequacy (Maximum Demand) assessment. This information is critical to understanding if the EV charge point or Heat Pump can be supported by the network. There are different approaches to determining a site’s MD, including:

• Use existing information – this is the best approach when there is available data on the specific loads in the house. However, this may not always be the case.
• Determine loads installed – this approach takes diversity into consideration where appropriate. For this purpose there are different guidelines to assist installers, including:
  • Electrical installation design guide – calculations for electricians and designers
  • On-site guide BS 7671:2018 – IET wiring regulations, 18th Edition

Please contact the IET if you have further questions on the guidance.

Some installers chose to post their customers an internet connected monitoring device which connects to the customer’s internet router and clamps a split Current Transformer (CT) around the supply meter tail. Data is then remotely collected over two weeks at ten minute intervals, before being analysed to arrive at an accurate MD without the need for a site visit.