Upgrade of house main fuse

Timdevnewbie said:
I contact my DNO (UK Power Networks) regarding my setup (6.5kw solar plus electric shower, immersion heater and maybe an EV point in the future, just granny charging for now... ) and they said I needed a new 100A fuse setup and also as I am on a looped supply with my neighbour they need to come along and dig up the road as well. They are booked in to do this in October. I'll let you know how it goes. The guys that came for an initial survey said best to book it in while it's still free as they could definitely see it becoming a paid for service in the future once everyone has EVs and solar..
(I had to jump through a few hoops about size of meter tails etc before they would come out. But we'd had a SMETS2 meter installed only a couple of years back so I knew this should be up to spec)
Hope this is helpful.
Tim
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I had the same problem. Looped supply. They came dug up 30m of road relaid cable. Sorted it out. No cost. Brilliant service. Couldn’t believe it. Mind you I’m in Wales !!!
 
This may be obvious, but for others reading who don't have their charger yet: When ours was installed it had a sense wire separate and parallel to the main current carrying cable. The sensor measures the total house consumption allowing the charge point to throttle back if the total consumption reaches the limit. The limit in our case is set, using the charger app, to 60A to match our main fuse. It's most unlikely to have to operate because we'd have to be unlucky to operate all the high current stuff at once (I charge at night) but it's reassuring to know I'm never going to blow the main fuse. I did not know about this feature ( which probably has an official name) when I ordered the charger. I lucked out and would have been happier if I'd known beforehand. Hence this post
 
Richard P said:
I thought my upgrade would be free too but our DNO charged over £100 simply to switch the existing 60A fuse for a 100A one, which took less than 5 minutes ☹️
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Given the job had only taken five minutes and you had a 60 Amp fuse before, then I have a strange feeling that you now have a 80 Amp fuse installed in its place.
Why ?.
Because generally the service head is the same size for a 60 and 80 Amp fuse, hence the really quick replacement time.
The 100 Amp fuse itself is physically larger in its actual size and is not interchangeable into the smaller service head.
Therefore the service head upgrade takes longer to perform.
As a rule, the DNO does not charge for this upgrade, but if I was being charged for the service, I would want the 100 Amp upgrade for sure !.
 
SteveM said:
This may be obvious, but for others reading who don't have their charger yet: When ours was installed it had a sense wire separate and parallel to the main current carrying cable. The sensor measures the total house consumption allowing the charge point to throttle back if the total consumption reaches the limit. The limit in our case is set, using the charger app, to 60A to match our main fuse. It's most unlikely to have to operate because we'd have to be unlucky to operate all the high current stuff at once (I charge at night) but it's reassuring to know I'm never going to blow the main fuse. I did not know about this feature ( which probably has an official name) when I ordered the charger. I lucked out and would have been happier if I'd known beforehand. Hence this post
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It may depend on the DNO but mine had an information page that specified for a EV charge point the minimum rating was to be 80A with 25mm² tails.
 
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We should be getting an ev charger installed in the next week or two. I’ve had quotes from electricians. The house is on its own supply but has a 60A cut out fuse.

The first said he would switch the 60A cut out fuse for 100A himself. I questioned him and he said he always has, he never bothers speaking to the DNO.

The second said 60A would be more than enough and it can be left alone.

Do either of those sound right?
 
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I had exactly the same situation. I’m not sure where you are but my installer contacted the board and they upgraded my 60amp fuse. As my house was part of a looped connection. To upgrade they had to dig up the road for about 30ms back to the mains. Lay a new cable and connect my house direct. This was done AT NO COST TO ME WHATSOVER!!! I was gobsmacked but they apparently are duty bound. You may just need a simple fuse change mind!!! I’m in Wales
 
I’m dubious about 60amp as overnight we will have the car charging, and washing machine and dishwasher going, at a minimum. The guy was adamant we had plenty of headroom though. And the other guy, well he would just change it without approval. They both said if I go down the DNO route I’ll be waiting for a very long time.
 
bobbarley said:
We should be getting an ev charger installed in the next week or two. I’ve had quotes from electricians. The house is on its own supply but has a 60a cut out fuse.

The first said he would switch the 60a cut out fuse for 100a himself. I questioned him and he said he always has, he never bothers speaking to the DNO.

The second said 60a would be more than enough and it can be left alone.

Do either of those sound right?
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You should avoid the first one. In most cases it is illegal for an electrician to remove/change the main fuse. It is also a requirement to notify the DNO of any significant change to the potential load. The second electrician is correct provided the charger has a load balancer and a current transformer (CT) is fitted to monitor the load.
 
It may depend on your DNO but it should be 80A on an exclusive supply.

It's not unusual for a sparks to pull the fuse carrier to carry out work on consumer units/meters safely. In principal it is hardly a huge leap to replace the cartridge but ONLY the DNO can say the upstream service is good enough for that increase in load.
 
bobbarley said:
We should be getting an ev charger installed in the next week or two. I’ve had quotes from electricians. The house is on its own supply but has a 60A cut out fuse.

The first said he would switch the 60A cut out fuse for 100A himself. I questioned him and he said he always has, he never bothers speaking to the DNO.

The second said 60A would be more than enough and it can be left alone.

Do either of those sound right?
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A 60amp fuse with 120 amp load takes 10 minutes to blow, it will depend on what other loads you are likely to run at the same time as charging your car. The chargers can usually be configured to reduce the car charging current if the demand on your grid supply approaches maximum. Final point, if you do manage to pop the fuse your DNO will be round in very quick time to replace it and probably upgrade it at the same time.
Did either electrician say they would contact the DNO to inform them of EVSE installation? Many dont bother but they should.
 
I did read on the site that Octopus sparkies are qualified to upgrade the fuse when installing charger?
 
johnb80 said:
A 60amp fuse with 120 amp load takes 10 minutes to blow, it will depend on what other loads you are likely to run at the same time as charging your car. The chargers can usually be configured to reduce the car charging current if the demand on your grid supply approaches maximum. Final point, if you do manage to pop the fuse your DNO will be round in very quick time to replace it and probably upgrade it at the same time.
Did either electrician say they would contact the DNO to inform them of EVSE installation? Many dont bother but they should.
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No neither mentioned it. I get the impression that a lot of electricians must see it as an annoying administrative task.
 
Like @Hairyfool said. The DNO needs to approve that the street supply can provide the extra load and next time the meter reader calls they will report back that the main fuse has been tampered with as the seal will be broken.
Why not give them a call and ask how long you would need to wait for them to upgrade the fuse?
 
I contacted them and they said an application form needs to be completed. I had a look at it, but it’s extremely complicated, I imagine they only intend for electricians to ever complete it.
 
I think most people have theirs upgraded to 80A or 100A, but it isn't necessarily required depending on what else you run in the house.

Informing the DNO is supposed to be done, but I don't think many independent sparkies do. Not sure mine did. I don't know. My fuse didn't need upgrading.
 
Before we had the fuse / cutout upgraded (the 60A holder is too small to take a 100A fuse) I used to regularly run 7KW charger + Washing machine + dishwasher + immersion heater in the 4hr Octopus Go window. It never blew the fuse, so you will probably be OK without the upgrade. However the rules have changed since my charger was put in so they will likely need to do a fuse upgrade anyway.
 
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