We recently had our main cut out fuse upgraded by our local DNO from 60 to 100 Amps.
Prior to this upgrade, we have charged using a dumb 7 Kw Rolec unit ( yeah I know
) installed in 2015.
We charged our VW PHEV ( 3.5 kw’s ) most nights on a cheap rate Off Peak tariff.
We did this without any problems for about four years.
Then we went full EV with the first Gen ZS EV.
Off Peak still on the 60 Amp fuse.
Except for the crap internals of the Rolec everything was fine.
Then we upgraded to the LR ZS EV with larger pack.
This happened just about the time when energy prices where going through the ceiling.
Naturally, we wanted to slide as much of our usage as possible, onto our 5 hour window of cheaper 4.5p / Kw Off Peak.
Quick bit of “Man Maths” told us that our 60 Amp rating could be compromised by the extra demands placed on it, hence the request fuse upgrade.
The dumb wall box does not have load balancing of course and to be honest, this was not going to very practical if it had !.
Running other high load electrical items, would have resulted in the wall box throttling back to protect the fuse ( which is the whole idea ) but then you could coming up short, on receiving a longer charge cycle at the cheaper rate.
Even if you are on a standard tariff, which means the cost to charge is the same, regardless of the time of day.
You can be restricted on the amount of items you are running at the same time.
E.G. - You arrive home from work and instantly put the car on charge ( 7 Kw’s ) you then put on the kettle ( 2.5 Kw’s ) and then decide to take a quick shower
( which is an electric unit pulling another 11 Kw’s ).
You are already over the limit on that 60 Amp protection fuse, before you even consider turning on the washing machine ( 2.5 Kw’s ) and the electric oven ( 3.0 Kw’s ) etc etc.
Houses of a certain age ( ours was built in 1982 ) it was normal practice to install a 60 Amp protection fuse.
This was more than enough to satisfy the demands back then !.
Today, this is a completely different story.
Having an EV and a cheaper Off Peak tariff helps everybody, including the national grid.
Sliding your usage into that Off Peak window is a good way of keeping your costs down.
But you do have to consider how much load you intend to pass through that fuse !.
It is surprising just how quickly you can creep up on that smaller rating !.
Yes - The fail rate on a 60 Amp fuse will be higher than 60 Amps rated on the fuse of course, but pushing it hard on a continual basis is not advisable to be honest.
The game has changed a lot now, from back in 2015 when we first started on our electric journey.
Load demand safety and huge increase in energy costs are the primary reason for our request to upgrade our protection fuse.
There is reported to be another 50% ( ish ) energy price increase due in Oct / Nov 2022.
Sliding your usage has never been so important if you are on a time of day ( Off Peak ) tariff.
My DNO said that they had seen a huge increase in the request for fuse upgrades in the last few months.
I think we all understand why !.
!.
