Help with my power supply

[bogdim]

Hi,

I keep reading that it's recommended to have 100 Amp fuse on your power supply for 7kw home charger, however looking at my setup I can't tell what I have.
Hoping someone here can help me.
I can see on the consumer unit that the maximum load is 100A. Is that it? or is the home charger not even connected to the consumer unit?
Sorry if my questions are dumb.

 

[Lovemyev]

Hi,

I keep reading that it's recommended to have 100 Amp fuse on your power supply for 7kw home charger, however looking at my setup I can't tell what I have.
Hoping someone here can help me.
I can see on the consumer unit that the maximum load is 100A. Is that it? or is the home charger not even connected to the consumer unit?
Sorry if my questions are dumb.

Wow ..... That is a very old MEM service head you have there my friend !.
Somebody with better experience in domestic electrics can offer some advice, but here is my view on what I see.
I would be extremely surprised too see a 100 Amp protection fuse in that service head, given it's age.
If I am reading correctly, the main isolation switch in the CU is rated at 100 Amps ?.
But I somehow doubt the main cartridge will be rated at 100 amps somehow ?.
The rating of the fuse is hidden behind that little door on the head unit.
It can not ( and should not ) be touched by ANYBODY but the DNO.
As you can see, the door is correctly protected by a stiff wire and a crimped lead seal.
Our house was built around 1981 and the DNO commissioned the property with a 60 Amp rated fuse.
Every other house close by, are ALL running on 60 Amp fuse's as well, it was considered MORE than enough back then.
Just to say, that a 7 kw wall box WILL run on a 60 Amp fuse with no problem at all.
I have been doing this for almost seven years now.
You just have to give a bit of thought to what and when, you will be placing a high demand on the system.
I ( like a lot of EV owners ) conduct their charging using cheaper off peak electric.
Charging in the early hours of the morning.
At this time, very little other power is being used, so not much chance of over loading the main fuse then.
But upgrading to 100 Amp fuse is now recommended, due to the increased demand of other electrical appliance we all are running these days !.
They are very likely to upgrade the size of the meter tails and install a 100 amp isolation switch at the same time.
It will depend on your DNO on just how they treat the upgrade process.
Some will upgrade from 60 to 80 FOC but then charge for an upgrade to 100 Amps.
Why ? - Because a 60 - 80 can sometimes be achieved by just switching out the main fuse cartridge in the service head.
To install a 100 Amp protection fuse, the service head needs to totally replaced first.
I think this will be the course of action in your case.
They will also check is you are on a "Shared / Looped" supply.
If so, this will require a LOT more work to split the supply.
Others will upgrade to 100 Amps FOC regardless ?????.
I your situation, I recommend you contact your local DNO - ASAP.

 

[Ozzie1989]

I'm no electrician btw...

I have the same service head as you and my DNO said there is no need to change it unless it's damaged.

I'm ordering a charger that has load balancing (most do now), if set correctly (e.g. for 60a fuse) it will constantly monitor and adjust charging so total house load doesn't exceed it.

Looking at your consumer unit, it's fairly new and those RCBOs are still available and in type A (your spare one is not suitable as it's type AC). Your installer will likely add a new type A RCBO, no need for additional fuse box etc.

I really wouldn't worry about your 60a fuse unless you intend to charge, run washing machine, tumble dryer, dishwasher and want to use an electric shower at the same time!

 

[Jomarkh]

When you get a quote for the 7.5kw charger hopefully they will advise you on Mem unit and possibly advise getting a load check for your DNO to see if you can get an 80or 100a fuse

 

[Alb]

Talk to your DNO regardless as they will inspect the service head and verify the rating of the installed fuse free of charge. Western Power Distribution did this for me and confirmed I had a 100A fuse.

 

[Justin H]

You can very easily keep to a 60 amp supply by charging through the night. Even if you don't have an off peak tariff it evens out your supply use. If you do want to upgrade and you are on a looped supply it will cost you a lot because you have a single cable coming in meaning you are the last house on the looped supply (usually 2 properties looped together). Contact your DNO to see what supply you have. If it is looped talk to your neighbour (first on the loop) and see if they want to upgrade if you go halves. They would only have to pay for a new cut out/fuse upgrade to their house and the DNO would have to pay for the installation of the new supply cable to you. Then you can get an upgraded 100A cut out and fuse at a lower cost overall. You only pay for work to your supply so if the neighbour applies for the upgrade the new cable gets laid free of charge.

 

[Webbo]

Hi,

I keep reading that it's recommended to have 100 Amp fuse on your power supply for 7kw home charger, however looking at my setup I can't tell what I have.
Hoping someone here can help me.
I can see on the consumer unit that the maximum load is 100A. Is that it? or is the home charger not even connected to the consumer unit?
Sorry if my questions are dumb.

I have a 100 amp incoming supply with an 80 amp main fuse, my Podpoint was installed and works fine, it monitors the use on the main cable and reduces the current to the Podpoint if the demand from the house & charger would overload the fuse.

 

[macd2401]

That is one crusty looking supply cable

 

[bogdim]

Thanks everyone, all of my home chargin would happen over night when there is very little electricity being used around the house. Anyway I'll contact UKPN to check with them first as I see quite a lot of you are shocked at how my service head and supply cable looks

 

[bogdim]

Update from UKPN:

Good morning. To install an EV Charger, your fuse would need to be 100amps. Unfortunately, we do not hold records of fuses as properties and would not be able to tell from the photos. An EV installer would be able to do a test on site to see if the fuse needs to be upgraded to 100amps or if it is already compatible. Most properties will be between 60 to 100 amps. If an installer has confirmed you do need to upgrade the fuse, then we can do this through our General Enquiries team, who you can contact on 0800 029 4285. The team are available Monday - Friday 09:00 - 17:00. We can upgrade to 100amps free of charge but anything over this would then become a chargeable job, but 100 amps is the standard for an EV charger anyway. Sorry we cant be more help and give the definitive answer if you would need to upgrade or not, but we just wouldn't be able to tell from the photos, and an installer would be able to confirm if this needs upgrading or not.

Apparently they upgrade to 100amps free of charge in case anyone else wants to do it.

 

[Ron61]

I've just had a quotation to upgrade my supply from 60a to 100a. Scottish and Southern quoted me £219.88. I've got a Henley Series 3 cutout box which apparently will take a 100a fuse but they want to replace it with a newer unit. So in effect they want me to upgrade their equipment at my cost. Told them to forget it.

 

[Lovemyev]

I've just had a quotation to upgrade my supply from 60a to 100a. Scottish and Southern quoted me £219.88. I've got a Henley Series 3 cutout box which apparently will take a 100a fuse but they want to replace it with a newer unit. So in effect they want me to upgrade their equipment at my cost. Told them to forget it.

I don’t blame you.
They are cheeky buggers !.
Our local DNO came out to my next doors neighbours house a few weeks ago.
He was running on a 60 Amp fuse the same as myself.
The EV installer who was going to fit a new Zappi recommended the upgrade.
The DNO replaced the complete service head and left in less that 20 minutes, all done !.
Totally FOC.
Apparently the service head that MANWEB installed back in the early 80’s will take an upgrade from 60 to 80 - but to install the larger 100 Amp fuse, the service head has to be replaced in order to carry the larger cartridge.

 

[Ron61]

They quoted me 3 hours work!

 

[Justin H]

Update from UKPN:

Good morning. To install an EV Charger, your fuse would need to be 100amps. Unfortunately, we do not hold records of fuses as properties and would not be able to tell from the photos. An EV installer would be able to do a test on site to see if the fuse needs to be upgraded to 100amps or if it is already compatible. Most properties will be between 60 to 100 amps. If an installer has confirmed you do need to upgrade the fuse, then we can do this through our General Enquiries team, who you can contact on 0800 029 4285. The team are available Monday - Friday 09:00 - 17:00. We can upgrade to 100amps free of charge but anything over this would then become a chargeable job, but 100 amps is the standard for an EV charger anyway. Sorry we cant be more help and give the definitive answer if you would need to upgrade or not, but we just wouldn't be able to tell from the photos, and an installer would be able to confirm if this needs upgrading or not.

Apparently they upgrade to 100amps free of charge in case anyone else wants to do it.

So they must of confirmed that you don't have a looped supply cable. That's good news. I don't know what test they are referring to. Anyone would have to visually check the fuse for size. If it's free then just upgrade to 100A. Northern Powergrid would charge me £360 for a fuse upgrade but my neighbour would not like his drive digging up so I have to stay at 60A.

 

[Alb]

Update from UKPN:

Good morning. To install an EV Charger, your fuse would need to be 100amps. Unfortunately, we do not hold records of fuses as properties and would not be able to tell from the photos. An EV installer would be able to do a test on site to see if the fuse needs to be upgraded to 100amps or if it is already compatible. Most properties will be between 60 to 100 amps. If an installer has confirmed you do need to upgrade the fuse, then we can do this through our General Enquiries team, who you can contact on 0800 029 4285. The team are available Monday - Friday 09:00 - 17:00. We can upgrade to 100amps free of charge but anything over this would then become a chargeable job, but 100 amps is the standard for an EV charger anyway. Sorry we cant be more help and give the definitive answer if you would need to upgrade or not, but we just wouldn't be able to tell from the photos, and an installer would be able to confirm if this needs upgrading or not.

Apparently they upgrade to 100amps free of charge in case anyone else wants to do it.

That's a confusing reply.
Technically, only the DNO is allowed to break the seal on the fuse carrier to visually confirm its rating. There is no test an EV installer could do that would tell him what the installed fuse size was. In reality of course, electricians break the seals and remove these fuses routinely as this is often the only way the consumer unit can be safely isolated.
It's absolutely not true that a 100A fuse is "standard" for EV charging as many here will attest. It gives you more headroom but you can function at 80 or 60A (particularly so if the charge point does load management).
That said, if 100A is available FOC then go for it. It will present a good opportunity to get an isolator fitted and make sure the tails and earth are correctly sized to the current standard.

 

[macd2401]

Could always ask you supplier to upgrade you to smart meters... that's how I found out all the problems with my supply (fused neutral, looped supply) coming from when the installer pulled the main fuse. Was then passed to the DNO who ended up replacing the cable, and giving me an 80A fuse.

 

[Toby]

7.2kw is 240V X 32amps. So the 100amp is because the ring main is usually 32amp and then the oven is usually on a 32 amp. So put the oven on (30amps) , the kettle (10amps) and a couple of heaters (20amps for 2*2kw) and the 60 amps is used. These days there are phones and TVs and WiFi boxes and loads of other appliances. The installer will do a full check on all these things as each house needs an individual assessment.

 

[mystreet]

Could always ask you supplier to upgrade you to smart meters... that's how I found out all the problems with my supply (fused neutral, looped supply) coming from when the installer pulled the main fuse. Was then passed to the DNO who ended up replacing the cable, and giving me an 80A fuse.

Correct me if I am wrong, but I am sure that it is a smart meter in the photos.

 

[Alb]

No need for correction, it is a smart meter!

 

[biffo]

I’ve got a three phase supply into house (well, certainly got three ‘100 Amp’ fuses installed. Only one phase connected to the meter though.

Turns out that my 100 Amp fuse is really an 80 Amp despite what the external label says. Hypervolt has a load clamp and knows of fuse capacity and will scale back its charge if too much load - was fine charging at same time as 8.5kW shower, was tempted to turn in oven, kettle and tumble drier to see if it scaled back but knowing my luck, the fuse would have popped!