Why did your dno limit you to 80A.  Was it a supply problem or because of inadequate meter tails (which they won't change). 

I ask because mine did this but also told me that if I had the meter tails changed I could ask them to come out again and upgrade to 100A.

To answer the question you asked an electrician should do a calculation of your load making some assumptions about 'diversity' (basically an allowance for the fact that not everything will be on simultaneously).  This tells them what capacity incoming you need.  They will also make some assumptions about the load on each socket circuit which may well be much higher than you actually need. 

It might be possible to adjust these assumptions by persuasion, or by reducing the capacity of the breakers on the circuits.  Many ring mains have 32A breakers from the days when we had electric fires.  These days the circuits are used predominantly for low wattage tech and the odd cooking appliance.  In many cases 20A would cover the load.  (As a matter of fact some electricians will exploit this by replacing the 32A breaker with a 20A one, which means that the restriction on numbers of sockets on a spur can be lifted. making for easier wiring if you need more sockets.)

I would try arguing the point particularly as presumably your heat pump is 8kW or less so only 16A?

@jamespa 

Thanks JamesPa,

Our DNO won't install anything more than 80A, in fact while they were changing our fuse, the neighbours came out and said can you update ours to 80A too please, assuming it was like ours 60A

Unfortunately theirs was already 100A and they dropped it back down to 80A.

I've just read up on diversity thanks, but unsure if octopus calculated using that.

Heat pump is 8kw, on the DNO form they put down 24A.

Hopefully octopus reply with a solution today.

Posted by: @njt

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Heat pump is 8kw, on the DNO form they put down 24A.

Would have thought looking at a data sheet that would be nearer 17A and that allows for an immersion to be driven directly from the heat pump. Have a look at you make model datasheet it will be on there.

@johnmo 

Hi Johnmo,

I've looked on the data sheet and it does say 24A,  recommended fuse 25A, so looks like it's the correct figures given to the DNO.

Posted by: @jamespa

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Why did your dno limit you to 80A.  Was it a supply problem or because of inadequate meter tails (which they won't change). 

@jamespa National Grid (Western Power) are on a mission to reduce to 80A on opportunity. If you want more you have to pay for 3-phase. 

That doesn't bode well for climate change mitigation, much of which, at a household level, depends on power electrification (car, heat pump, hob).

I had a similar pantomime with my DNO. My incoming fuse is 80A with 25mm2 meter tail L&N incomers from external fuse and meter box to internal consumer unit. DNO wanted £800 & 8 week lead time (not a typo) to upgrade the fuse to 100A. I would have to then replace L&N tail incomers between meter and my consumer unit. Both were a non-starter, fuse upgrade due to price & lead time, and incomers due to them being under a hard tiled floor in 3 rooms. So I remain with an 80A fuse and have a very slightly undersized 10kW ASHP with 17.5A max FLC and recommended breaker rating 20A. Next size up 13kW ASHP, which I was planning to fit, was not then not connect and notify and requires a 32A breaker. DNO would not accept that additional load onto the consumer unit with an 80A fuse.

@allyfish 

I rang our DNO on Friday they did the 60A to 80A swap on the Monday free. 

Did your heat pump require an electrical amp test?

I don't think I'm extreme by having solar, a shower, induction hob etc but I'm way over 100A according to octopus.

I’m a bit confused by the comments above. Why are DNOs reducing this when the UK’s goal is the electrification of everything: cars, heating, cookers, etc.

Can you please pop who your DNO is and which ones have been involved in these incoming fuse “downgrades”?

@editor 

Hi, 

My DNO is National Grid (West Midlands area).

I had a 60A fuse, they came out but would only replace it with an 80A fuse. All at no cost.

Our neighbours with same house who have lived there since new asked if at the same time as changing ours would increase theirs thinking 60A to 80A, but for some reason there's already had a 100A fuse installed.

They said they couldn't leave the 100A in and they replaced it with an 80A. 

Found this which may explain what is going on:

CONNECTIONS.NATIONALGRID.CO.UK "https://connections.nationalgrid.co.uk/news-and-events/latest-news/standardisation-of-fusing-to-80a#:~:text=National+Grid+Electricity+Distribution+(NGED,a+cutout+fused+at+100A"

National Grid - News

I read that UKPN is still doing 100A fuses.