100A fuse no longer allowed

[Andy]

I just tried to change my fuse to 100A. I was not allowed to with no real reason given by the load team. However, it's almost certainly because of the link given. I thought it might be an SSE thing but it is National Grid rules.

National Grid has changed the rules and the maximum allowed is 80A. They will even change 100A to 80 if they do some work in your house.

There is a nice graph given current drawn and time before it blows.

https://www.nationalgrid.co.uk/download ... eme/633928

[nowty]

I read that a few weeks back, Nowty Towers is 100A.

But to be honest I very rarely go over 80A, usually stay in the 60A to 70A range.

Unless of course its a free Power Hour and IOG cheap slots have been obtained.

[Andy]

I read that a few weeks back, Nowty Towers is 100A.

But to be honest I very rarely go over 80A, usually stay in the 60A to 70A range.

Unless of course its a free Power Hour and IOG cheap slots have been obtained.

Unfortunately I lost my E10 so in cold weather in Jan, charging the car/batteries and running the heat pump at high load means I struggle to charge all within a 7 hour window on the 80A fuse. I did discover the time to blow graphs so I'll be tweaking my settings on the car and chargers. I've been running at 73A to allow for kettles etc being put on. Turns out I don't really need to worry about that.

[dan_b]

This document says changes to be implemented in 2023, so this isn't a new thing.
Strangely enough was out on a film shoot in a domestic property with some engineers from one of the DNOs we work with last week and I jokingly said to them " might as well upgrade the fuse to 100A while you're here " and they did say "we'll we've got some in the van"...

So, eer. Not sure.

[nowty]

I wasn't sure if that doc is simply the National Grid DNO rather than the nationwide National Grid, now known as NESO. I just lookup up my local DNO and they still allow free fuse upgrades up to 100A (23kVA).

[Fintray]

Just checked on SSEN website and they still say up to 100A, they changed my one from a 60A to 100A last March when we had our heat pump installed.

I wasn't sure if that doc is simply the National Grid DNO rather than the nationwide National Grid, now known as NESO. I just lookup up my local DNO and they still allow free fuse upgrades up to 100A (23kVA).

Of course National Grid doesn't have the transmission network in Scotland as it is SSEN and Scottish Power that is responsible.

[Mart]

I wasn't sure if that doc is simply the National Grid DNO rather than the nationwide National Grid, now known as NESO. I just lookup up my local DNO and they still allow free fuse upgrades up to 100A (23kVA).

Ah, yes, I think it's the DNO. So that would be my area, previously WPD. We actually had our fuse upgraded when we got the car charger installed (or the installers got it done). I recall the conversation with the then WPD staff who told me they'd replaced the 60A fusebox with a 100A, but could only justify giving us an 80A fuse/breaker. But it could be reviewed if necessary later on. That was 2020.

Nice to know about the 100A for 4hrs guestimate, as I think we can get close to 80A if charging the car at 7kW, plus the battery charging at 3.68kW, plus both A2A kicking in, plus my plans for a HW tank at 2 to 4kW, but hopefully HP at ~0.5kW. Oil rads topping up room heat add another max of 1.7kW. It does add up, but not all sustained.

[cojmh]

When I had my incoming electric supply moved summer last year they replaced the 100A one I had with an 80A one.

I did ask for a 100A as I said I would be getting a car charge in the not too distant future but they said they couldn't do it and up until recently they were only allowed to install 63A fuses.

Their opinion (the fitters) was that the whole thing is crazy as the cable they were installing to the meter box was smaller than the meter tails in the house.

But it is interesting just how much current an 80A fuse will take and for how long!

[NoraBatty]

I wonder, cynically if this is a money making scheme.
Restrict to 80A, knowing there is a push for greener energy requiring higher Amperages into properties.
If you are restricted to 80A now, your only choice is to pay extortionate costs to upgrade to 3phase.
Thereby, stopping thw Grid from having to dive into their own pockets to upgrade the system for everyone.

I have seen a few videos on youtube of people getting free 3phase installed if they have a looped supply.
The DNO will upgrade the wiring supplying the looped properties to be 3phase capable, for free apparently and then its a case of proving you need over 80A to get it instaleld in house. The consumer board upgrades are on you though if so.

If you are on a looped supply, it is worth considering a call to get around the 80A that way.

[MrPablo]

Very good timing on this thread as I'm getting unlooped on the 19th Feb.
The project manager came out this week to discuss, confirm cable routes, etc.

My DNO is SP Energy, and in this case the max fuse is indeed 80A.
Saying that, they gave me the option of 3 phase to the property, down to single underground and then new service head in the same location.
The alternative (which I'm taking) was 3 phase to an externally mounted 3 phase head, then use one of the phases into the house.

I'll post pictures on the forum at the time for those who might be interested

Interestingly, DNO records suggest every house in the cul-de-sac have their own supply but at least 4 houses don't.