We had a Zappi installed in October 2024, we only had a 60 Amp fuse but Northern Powergrid wouldn't upgrade us. They said because we didn't have any other power intensive equipment e.g. Heat pump etc. that 60 A was enough.
What I have noticed is that on some modest properties you have the scenario: - Heat pump(s) - Solar and battery setup - Car charger(s) - Cheap tariff takes effect at 23:30 (you know the one) Now if people do anything (and they do) and every device is automated, then bang on schedule each night all of the above switch on full bore to rinse that cheap rate. I have seen these setups easily hit 20-24Kw for a decent chunk of the window on that single phase! I would like to know if there is a genuine reason for DNOs downgrading 100A to 80A, but maybe it is just to suppress some of the more enthusiastic consumers out there. Was going full import every night really what the energy suppliers/DNOs intended/expected? Can they handle more and more people each year doing this? Is it fair for people to take advantage of things in this way? Personally if the grid cannot handle this growing behaviour, I think you will start to see 60A and even 40A limits for some properties imposed... good luck!
I'm with SSE as a dno. I applied to upgrade to 3 phase 3x100 which was granted. On the day the guys said they were only installing 80A fuses everywhere now. I was given the same line of "80A wont actually blow till over 100A flowing". I made them a bacon roll and got 100A fuses... I currently have 2 EV chargers here, 50kWh battery and 20kWp of solar. Im looking to max out G99 next year with 50kW of inverter which has been approved but export limited to 23kW. When I was single phase only I had limits set up to keep current to 90A but I was regularly hitting that. We did actually have a PEN fault which occured when only drawing 73A but which had probably been brewing for a while. We are going to be seeing lots more of those in future and the regs haven't really kept up with how we are going to deal with them. Happily I had rods installed to enable island mode or a lot of stuff in the house would have gone live.
Yep, I had the same thing with Northern Powergrid. When we moved in to our current house it had an ASHP, an air to air HP and hot tub. I got a spark in to fit my car charger and also my battery storage (3kW inverter). I thought I was doing the right thing by notifying NPG of what I had as I was fairly sure the previous owner hadn't let them know about the heat pumps. They sent someone out to check the service head etc... and he replaced the 100A fuse with an 80. I've since done a G99 to replace the 3kW battery inverter with a 4.6kW hybrid which went through without issue or any work/costs. This is on top of an existing 2.5kW string inverter for an older FiT array. I was happy with a low or even zero export limit, but I was granted the full ~7kW of my two inverters combined. In reality although I do absolutely rinse it overnight with batteries charging, hot tub heating, DHW via the heat pump, dishwasher, tumble dryer, air con to boost heating 5-6am, car charging, etc... It's only really when the car is charging that I can routinely exceed 80A. The load curtailment on the Zappi stops that though. The told me the same thing about an 80A fuse being able to support 100A for a few hours. It doesn't seem like something I'd want to routinely test! I enquired about 3 phase just out of interest and they came back with a rough figure of £9k. The main cable is between 5-10m from the house from what they said. I declined to take it any further!
We have solar pv and an ev charger. Having a ASHP fitted and as we were on a looped system Northern Powergrid came to assess our supply. Yes, we were on a 100amp fuse, now we're going down to 80amp and still digging up next doors drive to unloop us.
Exactly what the Octopus meter fitter told me with UK Power Networks. Interestingly he found I had an 80amp fuse though I and the DNO thought it was 60.
UKPN has just upgraded our underground feed from 25mm Ally and 60A cutout fuse to 25mm Copper and 100A cutout fuse, free when we requested earlier this year after fitting solar and battery and said we were looking at aircon and EV.
Experience when getting a smart meter recently : We had a 100A-labelled main fuse. The smart meter guy (working with EOn) fitted the smart meter and said nothing about the main fuse, but I caught that it now had a sticker saying 80A. Conversation went like this... "Why have you changed the main fuse?" "I haven't" "Yes you have. I had a 100A fuse. I KNOW it said 100A. Now it says 80A. Why have you swapped it?" "Oh it's just that.... These fuses... They aren't what they say they are. It might have SAID it was 100A, but it could only really handle 80A. So I haven't changed the fuse. It's just a new label." Checking with some neighbours, a lot of other houses on my street (all circa 2007 newbuilds, all that would have had 100A same as mine) have been swapped for 80A. This seems like a strategy to lower everyone's supply rating sneakily without them knowing. I don't need 100A. I doubt I'll ever use more than 50A. But for people that do need to charge multiple EVs this is a bit cheeky to downgrade the supply ratings and push people into load-limiting at lower load with CT clamps, instead of supplying what was originally rated.
@@zXLuke4efcXz no, I haven't touched it. I was 50/50 on whether he was gaslighting me, or whether it's still the same fuse with just a different label stuck on it. But really it's fhe same either way: Last year if I wanted to use 100A I would have a leg to stand on if the operator had problems supplying what was claimed. I had a 100A supply and would have a valid complaint if their equipment didn't supply what they claimed. But now if I ask an EV charger fitter to fit multiple EV chargers, they would say it has to be clamped down below 80A just because that's what a sticky piece of plastic slapped onto the fuse says on the side. Whether they're actually swapping fuses, or just re-labelling existing fuses to lower values, the net effect is the same : It puts a lower limit on what the consumer is 'allowed' to use. Where the charger fitter would have clamped the chargers down to 80 on a fuse that says 100A, now they'll want to clamp it down to 60 to stay within an 80A-labelled fuse. I left it at that because for my purposes I don't have a lot of large draws, and won't need multiple EV chargers anyway, and not worth the argument. I just see it as something they are bringing in silently without any information to consumers, and seems targeted at forcing consumers to reduce load for the wrong reasons - it's not to protect the cable to the house, as that has not changed.
UK Power Networks upgraded my fuse from 60 Amp to 100 Amp about a year ago for free. The guys that came were going to fit 80 Amp but said they would go to 100 if possible. They replaced the entire head unit as my old fuse was from the 1960s.
Same here, UK Power Networks 1 year ago etc... Really thought I had a 80a fuse, but was a 60a/65a fuse with 16mm tails & they offered to upgrade it 80a max on existing header Or change header & fit a 100a - still on a TNS arrangement head unit 25mm tails etc... Yup, New mains header, 100a fuse, 25mm tails to meter - already had 25mm tails to Consumer Unit Never going to use anything like that, maybe only 50a if managed loads correctly/shifted etc... (I charge EV at reduced rate if I'm charging PV batteries keeping it to about 10 - 12kW max overnight) But good to know there's plenty there or way over spec the cabling where possible throughout, plus some earth rods in case they patch the TNS to TNCS Brilliant service from UKPN at no charge, very pleased with my DNO
At my previous house when I was looking at installing an ASHP, Northern Powergrid seemed happy to offer a free upgrade to 100A. In my new house, also Northern Powergrid, I have 3 phase with different size fuses. I asked about upgrading one of the phases to 100A and got told they don't do this anymore and if they have to visit site they will downgrade any 100A to 80A fuses. To simplify a solar and battery install, I want to put all loads on one phase but to make that possible that phase will need a 100A fuse. I haven't applied for this yet but perhaps the application will trigger a site visit. This change would definitely impact my solar and battery plans, I'd have to change the design which will affect the cost probably negatively. Any idea why this change of policy? They shouldn't be making it harder or more expensive to install all the renewable tech surely.
Seems to be a new policy as we had a lot of customers on 100a fuses. I wonder if they have many people pulling more than 100a on a 100a fuse a bit like people pulling 100a on a 80a fuse
Pretty sure they are doing it to avoid needing to change transformers and overhead lines. I know I am on a 200kva 3 phase transformer and 200A overhead lines which sse told me were rhe biggest pole mount units they do. If all the houses on my street pulled 100a at the same time, as more are likley to do moving forwards, that transformer could only run about 6 houses.
My DNO is doing this. They sent documentation saying we can run at 100A for a few hours at a time... but refused to confirm if they would charge me to replace the fuse if it blew
The chatter on the forums is that other DNOs are doing the same. I'm not clear whether that's on new installations or any time that they encounter one. I understand why DNOs might want to do this, but I'm concerned it will cause a lot of blown fuses in less knowledgeable households.
Northern Powergrid allowed my 100A to remain through the G99 process back in February this year. Is this latest move due to the CU 100A limit artificial worry nonsense that went out for comment recently?
I have 100amp when the smart meter was installed he tried to down grade me to a 80amp.Lucky I am a electrician and managed to keep the 100 amp. I have been to a couple of customer and the smart meter company has down graded them to 80 amp without letting the customer know. Its all because the power network cannot cope with the added load. My house was built is 1960 and still has the same cables feeding it. I have two zappi and 10kw battery.
Sp energy have done just this in midwales. I argued with them on behalf of my customer. Basically with heat pump and your home on all electric and 2 chargers it's not going to happen. You will be asked to use the second charger at half it's rate. We are going backwards not forwards. Net zero is a joke.
When DNO talked to me ref 80A Fuse, (Got 1950s supply Unlooped from next door and new cable fitted due to EV charger being fitted and future plan for solar PV). The new cable / supply can easily handle 100A but fuse was based on the risk that the consumer unit is rated to handle 100A thus they look at the combined power generation of solar and grid to come up with an over all safe working rating, for example 80A grid and 20A from solar. If they fit a 100A fuse and your also generating power from solar then your Consumer unit "potentially" could have more than 100A feeding your EV, Heat pump, kettle, tumble dryer etc. (Thats why 4.6kw Hybrid inverters seem to go through G99 process with ease - 20 amps x 230v = 4.6kw)
There is a train of thought where a house with solar should be on a 80 amp fuse rather than a hundred as generally consumer units are rated at 100 amps so in theory if you have 20 amp of solar and 100 amp main fuse you could have 120 amp load on the board bus bars. I doubt this is a risk as busbar generally are solid copper bar which will most likely have an in built safety factor so can take more than the 120 amps that could be drawn. But you know what these regulation setter type people are like. My point is perhaps the DNO are thinking about that bit I doubt it
Who needs 100A?. In Denmark where I'm living we have a 3 phase supply with 3x25A as standard. For most people even with a heat pump and ev charger it works fine with load sharing.
Yep. My house was built as 'all electric' in 1969 with 3-phase x 100A ! 2 phases were used for an old-fashioned warm air blower system & storage heaters, all on a "White meter" ( predated "Economy 7 ) - with mechanical timer for the cheap-rate overnight heating period. . . But, about 25 years ago I had gas connected to the house & gas central heating put in, with combi boiler, and the fuses on 2 of the phases were removed . . . It was marvellous. . . got rid of my immersion tank & header tank in the loft + hot water was almost instant & the heating system with radiators in place of the storage heaters was so much better !. . . But now we are looking at getting rid of gas & returning to an all electric house, with heat-pump, EVs , solar & batteries. . . We have already had the solar inverter & batteries installed. . . But before that, I got in touch with National Grid (our DNO) who said that they would gladly re-install the 3 phases as we already had it wired to the house. . I was expecting they would turn up and just add 2 more 100A fuses as it used to be. . but no. They removed the existing 100A fuse & added 3x80A fuses. In the meantime I got a 3-phase inverter installed & 2x 3-phase EV chargers ! . . but when I add everything up, I think we are going to have to be very careful about staggering EV charging & battery-charging (maybe using Home Assistant). . as if everything is going flat out at the same time + normal house load + potential induction hob + potential heat pumps . . . we'll be well over the 80A per phase !!
We had a Zappi installed in October 2024, we only had a 60 Amp fuse but Northern Powergrid wouldn't upgrade us. They said because we didn't have any other power intensive equipment e.g. Heat pump etc. that 60 A was enough.
Built a house in 2019 and they allowed a 100A fuse. Building a few houses now, 5 years later, and they only allow 80A.
What I have noticed is that on some modest properties you have the scenario:
- Heat pump(s)
- Solar and battery setup
- Car charger(s)
- Cheap tariff takes effect at 23:30 (you know the one)
Now if people do anything (and they do) and every device is automated, then bang on schedule each night all of the above switch on full bore to rinse that cheap rate. I have seen these setups easily hit 20-24Kw for a decent chunk of the window on that single phase!
I would like to know if there is a genuine reason for DNOs downgrading 100A to 80A, but maybe it is just to suppress some of the more enthusiastic consumers out there.
Was going full import every night really what the energy suppliers/DNOs intended/expected?
Can they handle more and more people each year doing this?
Is it fair for people to take advantage of things in this way?
Personally if the grid cannot handle this growing behaviour, I think you will start to see 60A and even 40A limits for some properties imposed... good luck!
… but that one also gives us an early slot almost everytime.
I'm with SSE as a dno. I applied to upgrade to 3 phase 3x100 which was granted. On the day the guys said they were only installing 80A fuses everywhere now. I was given the same line of "80A wont actually blow till over 100A flowing". I made them a bacon roll and got 100A fuses...
I currently have 2 EV chargers here, 50kWh battery and 20kWp of solar. Im looking to max out G99 next year with 50kW of inverter which has been approved but export limited to 23kW.
When I was single phase only I had limits set up to keep current to 90A but I was regularly hitting that. We did actually have a PEN fault which occured when only drawing 73A but which had probably been brewing for a while. We are going to be seeing lots more of those in future and the regs haven't really kept up with how we are going to deal with them. Happily I had rods installed to enable island mode or a lot of stuff in the house would have gone live.
Really interesting. Thanks for sharing 🙏
Recently upgraded from single to three phase and DNO fitted three 80A.
We had a DNO drop a 3 phase supply from 100a to 80a, on a light industrial unit, after we applied to install two 22kw chargers
Yep, I had the same thing with Northern Powergrid. When we moved in to our current house it had an ASHP, an air to air HP and hot tub. I got a spark in to fit my car charger and also my battery storage (3kW inverter). I thought I was doing the right thing by notifying NPG of what I had as I was fairly sure the previous owner hadn't let them know about the heat pumps. They sent someone out to check the service head etc... and he replaced the 100A fuse with an 80.
I've since done a G99 to replace the 3kW battery inverter with a 4.6kW hybrid which went through without issue or any work/costs. This is on top of an existing 2.5kW string inverter for an older FiT array. I was happy with a low or even zero export limit, but I was granted the full ~7kW of my two inverters combined.
In reality although I do absolutely rinse it overnight with batteries charging, hot tub heating, DHW via the heat pump, dishwasher, tumble dryer, air con to boost heating 5-6am, car charging, etc... It's only really when the car is charging that I can routinely exceed 80A. The load curtailment on the Zappi stops that though.
The told me the same thing about an 80A fuse being able to support 100A for a few hours. It doesn't seem like something I'd want to routinely test! I enquired about 3 phase just out of interest and they came back with a rough figure of £9k. The main cable is between 5-10m from the house from what they said. I declined to take it any further!
We have solar pv and an ev charger. Having a ASHP fitted and as we were on a looped system Northern Powergrid came to assess our supply. Yes, we were on a 100amp fuse, now we're going down to 80amp and still digging up next doors drive to unloop us.
Dno just swapped cut out for a customer and they have put 100 in.
Just pull the carriage and put your own 100a in 😂
Exactly what the Octopus meter fitter told me with UK Power Networks. Interestingly he found I had an 80amp fuse though I and the DNO thought it was 60.
UKPN has just upgraded our underground feed from 25mm Ally and 60A cutout fuse to 25mm Copper and 100A cutout fuse, free when we requested earlier this year after fitting solar and battery and said we were looking at aircon and EV.
Experience when getting a smart meter recently : We had a 100A-labelled main fuse. The smart meter guy (working with EOn) fitted the smart meter and said nothing about the main fuse, but I caught that it now had a sticker saying 80A. Conversation went like this...
"Why have you changed the main fuse?"
"I haven't"
"Yes you have. I had a 100A fuse. I KNOW it said 100A. Now it says 80A. Why have you swapped it?"
"Oh it's just that.... These fuses... They aren't what they say they are. It might have SAID it was 100A, but it could only really handle 80A. So I haven't changed the fuse. It's just a new label."
Checking with some neighbours, a lot of other houses on my street (all circa 2007 newbuilds, all that would have had 100A same as mine) have been swapped for 80A.
This seems like a strategy to lower everyone's supply rating sneakily without them knowing.
I don't need 100A. I doubt I'll ever use more than 50A. But for people that do need to charge multiple EVs this is a bit cheeky to downgrade the supply ratings and push people into load-limiting at lower load with CT clamps, instead of supplying what was originally rated.
Did you remove the fuse yourself to check it? It's pretty common to see them labelled as 100A, but actually have an 80A/60A fitted.
@@zXLuke4efcXz no, I haven't touched it. I was 50/50 on whether he was gaslighting me, or whether it's still the same fuse with just a different label stuck on it. But really it's fhe same either way: Last year if I wanted to use 100A I would have a leg to stand on if the operator had problems supplying what was claimed. I had a 100A supply and would have a valid complaint if their equipment didn't supply what they claimed. But now if I ask an EV charger fitter to fit multiple EV chargers, they would say it has to be clamped down below 80A just because that's what a sticky piece of plastic slapped onto the fuse says on the side. Whether they're actually swapping fuses, or just re-labelling existing fuses to lower values, the net effect is the same : It puts a lower limit on what the consumer is 'allowed' to use. Where the charger fitter would have clamped the chargers down to 80 on a fuse that says 100A, now they'll want to clamp it down to 60 to stay within an 80A-labelled fuse.
I left it at that because for my purposes I don't have a lot of large draws, and won't need multiple EV chargers anyway, and not worth the argument. I just see it as something they are bringing in silently without any information to consumers, and seems targeted at forcing consumers to reduce load for the wrong reasons - it's not to protect the cable to the house, as that has not changed.
Alot of jobs been to there definitely fitting 80amps as standard.
To do with local load planning 🤔
UK Power Networks upgraded my fuse from 60 Amp to 100 Amp about a year ago for free. The guys that came were going to fit 80 Amp but said they would go to 100 if possible. They replaced the entire head unit as my old fuse was from the 1960s.
Same here, UK Power Networks 1 year ago etc...
Really thought I had a 80a fuse, but was a 60a/65a fuse with 16mm tails
& they offered to upgrade it 80a max on existing header
Or change header & fit a 100a - still on a TNS arrangement head unit 25mm tails etc...
Yup, New mains header, 100a fuse, 25mm tails to meter - already had 25mm tails to Consumer Unit
Never going to use anything like that, maybe only 50a if managed loads correctly/shifted etc...
(I charge EV at reduced rate if I'm charging PV batteries keeping it to about 10 - 12kW max overnight)
But good to know there's plenty there or way over spec the cabling where possible throughout, plus some earth rods in case they patch the TNS to TNCS
Brilliant service from UKPN at no charge, very pleased with my DNO
80 amps is still 19,200 watts, so still plenty for a couple of car chargers if you are sensible with your load shifting and battery charging...
At my previous house when I was looking at installing an ASHP, Northern Powergrid seemed happy to offer a free upgrade to 100A.
In my new house, also Northern Powergrid, I have 3 phase with different size fuses. I asked about upgrading one of the phases to 100A and got told they don't do this anymore and if they have to visit site they will downgrade any 100A to 80A fuses.
To simplify a solar and battery install, I want to put all loads on one phase but to make that possible that phase will need a 100A fuse. I haven't applied for this yet but perhaps the application will trigger a site visit. This change would definitely impact my solar and battery plans, I'd have to change the design which will affect the cost probably negatively.
Any idea why this change of policy? They shouldn't be making it harder or more expensive to install all the renewable tech surely.
Seems to be a new policy as we had a lot of customers on 100a fuses. I wonder if they have many people pulling more than 100a on a 100a fuse a bit like people pulling 100a on a 80a fuse
Pretty sure they are doing it to avoid needing to change transformers and overhead lines. I know I am on a 200kva 3 phase transformer and 200A overhead lines which sse told me were rhe biggest pole mount units they do. If all the houses on my street pulled 100a at the same time, as more are likley to do moving forwards, that transformer could only run about 6 houses.
Mines been reduced to 60A in Summer without my knowledge
Northern powergrid
My DNO is doing this. They sent documentation saying we can run at 100A for a few hours at a time... but refused to confirm if they would charge me to replace the fuse if it blew
Hmmmm interesting!
The chatter on the forums is that other DNOs are doing the same. I'm not clear whether that's on new installations or any time that they encounter one.
I understand why DNOs might want to do this, but I'm concerned it will cause a lot of blown fuses in less knowledgeable households.
Northern Powergrid allowed my 100A to remain through the G99 process back in February this year. Is this latest move due to the CU 100A limit artificial worry nonsense that went out for comment recently?
I have 100amp when the smart meter was installed he tried to down grade me to a 80amp.Lucky I am a electrician and managed to keep the 100 amp. I have been to a couple of customer and the smart meter company has down graded them to 80 amp without letting the customer know. Its all because the power network cannot cope with the added load. My house was built is 1960 and still has the same cables feeding it. I have two zappi and 10kw battery.
Most in my area are 80amp unless they pay for 100 amp service
Seems like they may be refusing that 100a service going forward
Going backwards @@OvalRenewables
Been putting 80 A for years
Wonder if Northern Power would refund what he paid to go to 100amp?
Don't be silly
Sp energy have done just this in midwales. I argued with them on behalf of my customer. Basically with heat pump and your home on all electric and 2 chargers it's not going to happen. You will be asked to use the second charger at half it's rate. We are going backwards not forwards. Net zero is a joke.
When DNO talked to me ref 80A Fuse, (Got 1950s supply Unlooped from next door and new cable fitted due to EV charger being fitted and future plan for solar PV). The new cable / supply can easily handle 100A but fuse was based on the risk that the consumer unit is rated to handle 100A thus they look at the combined power generation of solar and grid to come up with an over all safe working rating, for example 80A grid and 20A from solar. If they fit a 100A fuse and your also generating power from solar then your Consumer unit "potentially" could have more than 100A feeding your EV, Heat pump, kettle, tumble dryer etc. (Thats why 4.6kw Hybrid inverters seem to go through G99 process with ease - 20 amps x 230v = 4.6kw)
There is a train of thought where a house with solar should be on a 80 amp fuse rather than a hundred as generally consumer units are rated at 100 amps so in theory if you have 20 amp of solar and 100 amp main fuse you could have 120 amp load on the board bus bars. I doubt this is a risk as busbar generally are solid copper bar which will most likely have an in built safety factor so can take more than the 120 amps that could be drawn. But you know what these regulation setter type people are like. My point is perhaps the DNO are thinking about that bit I doubt it
Im not sure my electrician told northern powergrid about my EV charger....
😅😅
Who needs 100A?. In Denmark where I'm living we have a 3 phase supply with 3x25A as standard. For most people even with a heat pump and ev charger it works fine with load sharing.
Majority of UK homes are single phase. Although that should change in time
@zjzozn I know, but the amps are the same. If I have 3x25A=75A it's almost the same as your 80A.
stick to diesel much less amperage
I think my "Diesel" has 140amp charger! And ford call it smart regenerative charging!
800kwh battery.
92kw motor.
550mile range.
Full charge in 4mins.
Yep. My house was built as 'all electric' in 1969 with 3-phase x 100A ! 2 phases were used for an old-fashioned warm air blower system & storage heaters, all on a "White meter" ( predated "Economy 7 ) - with mechanical timer for the cheap-rate overnight heating period. . . But, about 25 years ago I had gas connected to the house & gas central heating put in, with combi boiler, and the fuses on 2 of the phases were removed . . . It was marvellous. . . got rid of my immersion tank & header tank in the loft + hot water was almost instant & the heating system with radiators in place of the storage heaters was so much better !. . . But now we are looking at getting rid of gas & returning to an all electric house, with heat-pump, EVs , solar & batteries. . .
We have already had the solar inverter & batteries installed. . .
But before that, I got in touch with National Grid (our DNO) who said that they would gladly re-install the 3 phases as we already had it wired to the house. . I was expecting they would turn up and just add 2 more 100A fuses as it used to be. . but no. They removed the existing 100A fuse & added 3x80A fuses. In the meantime I got a 3-phase inverter installed & 2x 3-phase EV chargers ! . . but when I add everything up, I think we are going to have to be very careful about staggering EV charging & battery-charging (maybe using Home Assistant). . as if everything is going flat out at the same time + normal house load + potential induction hob + potential heat pumps . . . we'll be well over the 80A per phase !!