60 to 100amp fuse upgrade

[Jibjab]

Hi All

I’ve placed my order and am awaiting an delivery date. In preparation I’ve had my meters upgraded to SMETS 2. Whilst the engineer completed this he logged a fault that I might not be able to have an electric charging point installed due to having a 60amp fuse. I’ve contacted the power grid and they are hopefully going to replace the fuse pending a survey.

Has anyone else had this upgrade completed? Simple as a swap out, or more extensive ground works required? Is it actually a requirement to have a 100 amp fuse?

Any help and sharing of experiences appreciated.

James.

 

[MOBB]

Mine was also 60 amp - the guy from the DNO upgraded it to 100 amp free of charge, I wasnt there when he did it, but he wasnt there long at all.

 

[Jibjab]

Mine was also 60 amp - the guy from the DNO upgraded it to 100 amp free of charge, I wasnt there when he did it, but he wasnt there long at all.

Thanks for the response. I’m assuming/hoping it won’t be too obtrusive!

 

[NorfolkMustard]

Depends what the cable from the street to your house is, and the main tails into your meter & consumer unit. If they can handle 100amp then should be a quick swap.

 

[twlr]

Currently going through the process. It really depends on how good your wiring in to the property is. It sounds like an upgrade to 80a is easy enough, but 100a involves having a suitable cable going in to the house, as well as the tails (cables) between the main fuse and meter, and meter and fuse board, oh and the fuse board too, all being upgraded to support it.

We're currently looking at having to upgrade everything!

Conveniently it's different people who look after the different parts:
DNO - main fuse
your electricity provider - tails from main fuse to meter and the meter itself
electrician - tails from meter to fuse board and the fuse board itself

We're currently coordinating between all 3 to get everything upgraded!

 

[Jibjab]

Currently going through the process. It really depends on how good your wiring in to the property is. It sounds like an upgrade to 80a is easy enough, but 100a involves having a suitable cable going in to the house, as well as the tails (cables) between the main fuse and meter, and meter and fuse board, oh and the fuse board too, all being upgraded to support it.

We're currently looking at having to upgrade everything!

Conveniently it's different people who look after the different parts:
DNO - main fuse
your electricity provider - tails from main fuse to meter and the meter itself
electrician - tails from meter to fuse board and the fuse board itself

We're currently coordinating between all 3 to get everything upgraded!

Thanks for the response. So is it an actual requirement to have 100 amp for a charging point? I was looking at the Anderson and it mentions 100amp, but wasn’t sure if that was just for the Anderson or a preference rather than requirement. The lady I spoke to at the power grid asked if I wanted 80 or 100, I believed I needed 100, but 80 would, potentially, be an easier easier install?

 

[MrBadger]

No requirement. You could get away with 60A. But...

On installation of the charge point, the installer should do calcs on the existing home power usage and what effect the new charging load will add. If its above a certain level compared to the fuse, then DNO approval cannot be done retrospectively after install and you will not get full power that you want until the problem is resolved by the DNO. There should be no issue in this for first charge point, but it adds to inconvenience and may require a second trip for installer to then up the amps in the charge point.

 

[Dilly]

I had my two Zappi’s and single Powerwall on a 60amp fuse
Before the second Powerwall and extra PV went in I had it upgraded to 100amp.
The incoming power lines were capable of supporting 100 amp so just a 5 minute job for the DNO to swap out the fuse

 

[LukeUK]

A typical charging point allows the car's chargers to draw up to 32A. On top of this, you've also got to consider all of your other house loads, though these won't all be on at the same time.

Other significant loads;

- Electric oven
- Electric hob
- Shower
- Immersion heater
- Kettle
- Other household items

The issue is if you have a total load that exceeds the fuse rating for any period of time.

In addition, your local infrastructure, and the capacity of the local step-down transformer, have to be able to accommodate the (potential for) increased load.

Of course, you don't have to charge at 32A. It's possible, but slow, to charge at anything down to 6A.

 

[Glan gluaisne]

As above. To go up to a 100 A main fuse requires that both the incoming cable to the house and the tails, are OK for that supply current. Most houses built earlier than about 25 years ago may well only have 16mm² tails, and that will limit the fuse that can be fitted to 80 A (or should do, if they notice).

If the incoming cable is 35mm², as the majority of those installed in the last few decades will be, then there shouldn't be a problem on that side, although this does depends a bit on what the local LV network load is. Sometimes supplies were restricted to 60 A because the local LV network wasn't able to provide any more than this safely.

If you do have 16mm² tails, then having these upgraded to 25mm² at the same time as the charge point is installed isn't a big job, maybe half an hours additional work and about £10 in materials. If you post a photo of the installation (incoming cable, fuse, meter and tails) it might be possible to tell what size the tails are. If the tails do need upgrading, it's a very good idea to have an isolating switch fitted at the same time, as they make working on the installation downstream of the meter a lot easier.

If you are stuck with not being able to go above 60 A, then there are solutions available to still allow a charge point to be installed. One solution is to install a priority board in place of the box for the charge point connection etc, that will ensure the total house load never exceeds 60 A, by shutting the charge point down if there are heavy loads on in the house. A simpler way still is to get your electrician to put a peak current monitor on the incoming supply and leave it there for a couple of days of normal use. If the peak current demand is below about 28 A, then there shouldn't be a problem installing a 32 A charge point. Also, some charge points (perhaps only the Zappi at the moment) can sense the total demand on the house supply, and just reduce the signalled charge current a bit if needed. This needs the Harvi add on, but is another potential solution if you do end up supply current limited.

 

[MOBB]

As I said mine is now 100 amp after the DNO upgraded it, but I have 2 EO mini chargers fitted.

The installer recommended I set one at 32 amp and the other at 16 amp to be on the safe side usage wise, but its only the 2 of us that live there so we've never had an issue.

Our house is a 1960's build and the electrics looked a little "old" when we moved in last year, we have since changed the RCD fuse box, all is good. I believe the tails were changed by someone, cant remember who lol

 

[Plagued]

When we had our meter replaced 3 years ago, they noted the 60A fuse and said they had booked in an upgrade to allow for a charger. 3 years on and I've still not had the work done, I've had two visits from smart meter installers that can't get a mobile signal in the house and abandoned the install. luckily (or unluckily) the tesla is too low/long to get over the lip of our sloped drive so I can't home charge it anyway, and a 3 pin plug is fast enough for a leaf so I've not bothered chasing them.

 

[Jibjab]

Thanks for all the responses, really useful. The house is a 5 bed 4 bath detached but with no electric showers. We do have air conditioning, an induction hob and two ovens as the main power hungry consumers though I guess. It was extensively (approximately doubled in size) in 2008, existing house is 60’s, and I think rewired. We have an upstairs and downstairs circuit, two separate fuse boards both with RCDs. It seems everything apart from the ancient looking 60amp has been upgraded. If it’s minimal work/cost it makes sense to get 100amp done. Will see what they say

 

[Cnixon]

Tails may not be loaded by your charger if the charger supply comes directly off the meter. Zappi + the incomer load measuring thingy (sorry) will work.

 

[Glan gluaisne]

If the wiring was upgraded in 2008 then you should have 25mm² tails, as they were mandatory by then. The chances are the incoming cable may well be 35mm², as that's been pretty standard for a long time now. Provided the DNO are OK that the local LV network can handle the load there shouldn't be an issue with swapping the fuse, although if the head is old then they will most probably change the whole cutout as the older ones do degrade with age, sometimes quite badly, with the fuse holder becoming so brittle it almost falls apart when removed.

 

[Jibjab]

If the wiring was upgraded in 2008 then you should have 25mm² tails, as they were mandatory by then. The chances are the incoming cable may well be 35mm², as that's been pretty standard for a long time now. Provided the DNO are OK that the local LV network can handle the load there shouldn't be an issue with swapping the fuse, although if the head is old then they will most probably change the whole cutout as the older ones do degrade with age, sometimes quite badly, with the fuse holder becoming so brittle it almost falls apart when removed.

Brilliant, thanks for that. It’s all new to me this, and the “we can save some money” line I keep trotting out to the other half is getting harder to keep to if I end up having to dig the drive up etc

 

[Jason71]

I have had a 32amp charge point for 9 months with a 60amp fuse. Electrician said it was marginal and recommended an upgrade. DNO said it was OK to install anyway. 9 months later I am finally getting an 80amp and a new cut-out next week. If they actually turn up this time.

 

[Jibjab]

I have had a 32amp charge point for 9 months with a 60amp fuse. Electrician said it was marginal and recommended an upgrade. DNO said it was OK to install anyway. 9 months later I am finally getting an 80amp and a new cut-out next week. If they actually turn up this time.

I wonder if it’s Anderson being particularly cautious about 100amp? It seems clear that they won’t install unless you have 100 amp already though: Your Guide to EV Charger Installation | Andersen EV

 

[Glan gluaisne]

I have had a 32amp charge point for 9 months with a 60amp fuse. Electrician said it was marginal and recommended an upgrade. DNO said it was OK to install anyway. 9 months later I am finally getting an 80amp and a new cut-out next week. If they actually turn up this time.

TBH, we'd be fine on a 60 A fuse, too. Due largely to the increasing number of low energy appliances in use, and the gradual binning of older stuff that used way more power than it needed to, electricity demand had dropped a lot over the past 10 years or so. Despite electricity being our only energy supply, I've not seen the total house load exceed about 20 A when the car's not charging. The house idles at around 300 W, and that's a bit high, because we have an air pump for the sewage treatment plant, a UV disinfection unit for our drinking water supply, plus the fans in the house ventilation system all of which run 24/7.

Looking at the pattern of demand, we get a peak of around 3.5 kW to 4 kW when cooking, but only for short periods of time, a peak when the water heating comes on overnight, which adds about 3 kW to the demand, and maybe another kW or two peak when the heating it on overnight. The biggest load is car charging, but that's also only on overnight, so may be at the same time as the water and house heating, but won't coincide with cooking. The highest peak demand I've seen has been just under 12 kW (roughly 52 A at 230 VAC), and that was unusual, as the car was charging, the hot water was heating, the ASHP was heating the house and the borehole pump was on for a few minutes because the filtration system was backwashing.

 

[Glan gluaisne]

I wonder if it’s Anderson being particularly cautious about 100amp? It seems clear that they won’t install unless you have 100 amp already though: Your Guide to EV Charger Installation | Andersen EV

It's just up to the installer's assessment of the installation and the likely total load. The charge point manufacturer won't know anything about that, as it's up to the installing electrician to assess the existing installation and ensure that anything he installs doesn't take the load current over that which can be safely handled by the installation.

As mentioned above, it's acceptable to put a peak reading clamp meter on the supply, leave it there for a day or two of normal household operation and use that as the basis for establishing whether or not it's safe to install a 32 A charge point. That's not information that any charge point manufacturer would know, as it varies a great deal from one house to another.

For example, as outlined above, a 60 A supply could be fine with a 32 A charge point for a house that doesn't present high normal loads on the supply. On the other hand, the same 60 A supply would definitely not be OK if the house had an electric shower that was in regular use, as that would probably draw over 40 A all the time it was on.