National Grid fuse upgrade to 80A

NedS

I have read a few related threads here, and note some have some first hand experience, so hoping for a little advice.

We have recently had an ASHP and solar panels installed. NG (our DNO) have been notified of the solar installation (3.6kW) for SEG purposes , but I do not know whether the installer has notified NG of the ASHP install (as they are required to do within 28 days of installation under connect and notify arrangements). I can call NG to find out now the 28 day period has elapsed.

We currently have a 60A fuse, and I would like this upgraded to 80A. I understand this can be completed for free by National Grid where it relates to installation of energy saving / green measures as in this case. The installers did not appear to do much by way of an assessment as to whether 60A was sufficient. We have a 9kW electric shower, 2 x 2.5kW dual electric ovens and an electric oil filled radiator used for space heating in winter plus the usual fridge freezer and chest freezer etc. The new equipment includes a 12kW ASHP (rated at 6.44kW input on the ENA Heat Pump database) and an external 3kW immersion heater to supplement DHW. Solar is on a 3.6kW inverter with export capability (not sure how this factors in)

In winter, with heating/DHW in full use, we could easily exceed our 60A rating.

I have looked at the application process on NG's website, and it looks onerous to say the least. Is there an easier process? Could I phone NG, inquire if the installers have notified of the ASHP, and assuming not, request a fuse upgrade to 80A (18.4kW supply)?

https://connections.nationalgrid.co.uk/make-a-change/fuse-upgrade/

Any advice on how best to proceed much appreciated.

matelodave

we already had a big juicy 100A fuse when we changed from storage heaters to an ASHP

mnewtonuk

I had my fuse upgraded to 80A by National Grid a couple of months ago. Like you I was put off by the application process when I started filling in the form.

I ended up just filling in their general enquiry form - https://www.nationalgrid.co.uk/contact-us/contacting-national-grid-electricity-distribution/general-contact-enquiries saying that I was advised by my electrician to request a fuse upgrade due to some new installations.

I received an email response the next day saying that it had been referred to my local team, they called me up the next day and arranged an install the following week.

It ended up being surprisingly painless, I hope you have the same outcome.

doodling

Hi,

There should be a "contact us" email on their new supplies page - send them an email saying where you live and that you want to upgrade to 80A for an ASHP and I would ezpect that they will put you in touch with someone to get it booked in.

It might be helpful to add a picture of your supply to that email for their information.

National Grid have a policy of not installing 100A domestic supply fuses any more so 80A will be the biggest you get.

Netexporter

I had mine upgraded by NG. I just rang up and it was done within a week or two. They changed the service head whilst they were about it.

Scot_39

doodling said:

Hi,

There should be a "contact us" email on their new supplies page - send them an email saying where you live and that you want to upgrade to 80A for an ASHP and I would ezpect that they will put you in touch with someone to get it booked in.

It might be helpful to add a picture of your supply to that email for their information.

National Grid have a policy of not installing 100A domestic supply fuses any more so 80A will be the biggest you get.

Why ?

If I have hw immersion 3kW, storage heaters 7kW on E10 meter ALCS and electric shower (9or 9.5kW ?) all active for c10m some days - as i do try to time showers to my e10 off peak.

I can easily and even seen the ihd saying pulling over 20kW - 87A at 230V.

And that's only a fraction of theoretical max demand in a small 2 bed with conventional electric.

I have 2 fan and 2 panel heaters with timers in other rooms - about another 5-6kW max - not to mention cooker, washing machine - both 2-2.5 kW etc.

I could probably quite easily attempt to pull 100A.

But as an old all electric build I have the 100A rated fuse - are you saying they might really derate to 80A if needed repaired ?

NedS

Thanks for the replies everyone.

Scot_39 said:

doodling said:

Hi,

There should be a "contact us" email on their new supplies page - send them an email saying where you live and that you want to upgrade to 80A for an ASHP and I would ezpect that they will put you in touch with someone to get it booked in.

It might be helpful to add a picture of your supply to that email for their information.

National Grid have a policy of not installing 100A domestic supply fuses any more so 80A will be the biggest you get.

Why ?

If I have hw immersion 3kW, storage heaters 7kW on E10 meter ALCS and electric shower (9or 9.5kW ?) all active for c10m some days - as i do try to time showers to my e10 off peak.

I can easily and even seen the ihd saying pulling over 20kW - 87A at 230V.

And that's only a fraction of theoretical max demand in a small 2 bed with conventional electric.

I have 2 fan and 2 panel heaters with timers in other rooms - about another 5-6kW max - not to mention cooker, washing machine - both 2-2.5 kW etc.

I could probably quite easily attempt to pull 100A.

But as an old all electric build I have the 100A rated fuse - are you saying they might really derate to 80A if needed repaired ?

Their rationale for standardising on 80A is that a slow blow 80A fuse can withstand 100A load for 4 hours before blowing:

https://www.nationalgrid.co.uk/downloads-view-reciteme/633928

Netexporter

I tried for a 100A fuse, but got an 80A, because the new consumer unit has 100A breaker, but I now realise that it isn't necessary. If the transient load did exceed 100A then the breaker would deal with it, long before the company fuse was in any danger.

Reed_Richards

When I got my ASHP, my installer made the arrangements for the mains fuse upgrade.  Although the cover to the fuse was clearly labelled 60 A, when the DNO installer came and removed the cover it turned out there was an 80 A fuse already inside!  Since an 80 A fuse upgrade was all the DNO wanted to give me, I just kept the fuse I already had.  

Ectophile

Scot_39 said:

doodling said:

Hi,

There should be a "contact us" email on their new supplies page - send them an email saying where you live and that you want to upgrade to 80A for an ASHP and I would ezpect that they will put you in touch with someone to get it booked in.

It might be helpful to add a picture of your supply to that email for their information.

National Grid have a policy of not installing 100A domestic supply fuses any more so 80A will be the biggest you get.

Why ?

If I have hw immersion 3kW, storage heaters 7kW on E10 meter ALCS and electric shower (9or 9.5kW ?) all active for c10m some days - as i do try to time showers to my e10 off peak.

I can easily and even seen the ihd saying pulling over 20kW - 87A at 230V.

And that's only a fraction of theoretical max demand in a small 2 bed with conventional electric.

I have 2 fan and 2 panel heaters with timers in other rooms - about another 5-6kW max - not to mention cooker, washing machine - both 2-2.5 kW etc.

I could probably quite easily attempt to pull 100A.

But as an old all electric build I have the 100A rated fuse - are you saying they might really derate to 80A if needed repaired ?

It's not unknown for 100A fuses to be down-rated to 80A if work is done.  Many of the "100A" supply cut-outs weren't really up to the job and would over heat if run at 100A for more than a short while.

If you actually draw 100A, your electricity bills will be frightening.  It works out around £6.20 per hour.

Scot_39

Never quite seen the full 23 kW - for 100A at 230V - and the 20 kW - possibly only for 5-10 min if shower in use at same time as heaters charging and HW immersion (itself only typically 15-20 min 3 times a day).

It's just if I add the power of all the things that I might want to coordinate with my off-peak - and in my region and with E10 - that includes an early afternoon (1-4pm GMT) and late evening slot (8-10pm GMT) which some days I will use for cooking, washing machine and even showering when suits daily plans - the 100A let alone the 80A - is not as generous as it might seem.

But the article says it has considered EV and ASHP roll out - and in fact change driven (at least in part) as worried about thermals as expecting high loads becoming more common in summer.

It's also interesting they are also then suggesting the default 3 phase will be with 60A - or about 13.8kW at 230V (more strictly 13.8 kVA) per phase - some domestic cold fed electric showers are 10.8kW = approx 47A.

Wonder how many normal electric suppliers support 3 phase meters these days ?