Home charger on a 5amp house?

[ukslim]

I probably ought to ask on a non-brand-specific EV forum, or just an electrician's forum, but hey, I've got an account here

My sister-in-law is considering a salary-sacrifice lease, which would be great for her I think. But she said "I'd have to get a hybrid, because I can't charge here and there's nowhere I could charge nearby". Tut.

Well, she parks off the street next to her house. There's certainly an obvious place to put a home charger.

BUT, it's her mum's old house, and it has ancient wiring. 5amp sockets in most rooms. I checked the consumer unit, and it's pretty spartan. There's a modern-looking meter (don't think it's smart, but it has a digital display), but other than that it's a bakelite fusebox, no RCDs, and I couldn't find a main fuse to read its rating.

Does anyone have an idea how much of a problem this is likely to be for installing a wall box?

Looking at my own charger install, I think the charger's supply comes directly from the meter, independently of the rest of the house's RCD panel. It has its own separate RCD. So maybe none of this is a problem, except the main fuse rating for the house perhaps?

(If you have professional expertise, please say so in your answers!)

 

[Gadget Geek]

No expert, but I believe the DNO will change any main fuse that needs upgrading, free of charge (well, it's in the standing charge). My wall charger has it's own RCD and isolator switch.

 

[siteguru]

What matters (in respect of a wall box) is not the rating of the house sockets, but the rating of the main incoming fuse. (Usually located as the first item on the incoming mains line ... Mains --> Fuse --> Isolator --> Meter --> Consumer Unit).

If you have a 100A fuse then there's usually no issue with installing a 7kW wall box. 80A is usually OK too - anything below that then needs special considerations; either increasing the fuse size (if possible) or installing CT clamps to prevent the whole system being overloaded.

(I've no specific qualifications but have a general understanding).

 

[Grriff]

I'm not a qualified electrician but have rewired two houses. Apart from the general recommendation that the house needs rewiring especially if it has old rubber covered cables, you will need to check the earthing available. I'd get an electrician to check the installation, which they will need to do in order to provide a quote.

 

[Lovemyev]

With the house electrics being that old, the DNO are likely to take an interest in the size / handling capacity of the incoming supply cable to the house.
Surely there has to be a main cut out fuse protecting the property somewhere / somehow ?.
Is it in another part of the house ???.
I did not think that any round 5 Amp ( none fused protected ) three pin plugs, were still being used to run electrical equipment anymore !.
That is really old school.
If the consumer unit is THAT old, then it’s a pretty safe bet to say, that the wiring is likely to be well past its sell by date equally.
I would advise caution you could be opening up a can of worms here ?.

 

[ukslim]

I did not think that any round 5 Amp ( none fused protected ) three pin plugs, were still being used to run electrical equipment anymore !.
That is really old school.

Yes it is old school I think it's been like that since the 60s at least -- it's my wife's childhood home.

You're right, there must be a main fuse somewhere - I just couldn't spot it.

They are fused - I know this because we had them in my student accommodation in the 90s. We would all stick a 5amp plug on a 13amp 4-way gang socket, defeat the 5amp fuse with a paper clip or something, and merrily use it in the assumption that a fuse upstream would protect us ?.

Most of the family has observed at one time or another that the whole house should be rewired, but it would be hugely disruptive, and it doesn't generally cause her any grief.

 

[tsedge]

It is a difficult one, I would have thought the whole place needs rewiring and could be a fire risk if it is really dating from the 60s. That is decades past the lifespan of the wiring.

But obviously this would be very disruptive.

It is always possible to run a new consumer unit from the heads and put a charger on new wiring on that, but how comfortable a sparky will be doing that is anyone's guess.

NB: I am not an electrician.

 

[Lovemyev]

They are fused - I know this because we had them in my student accommodation in the 90s.

The circuit(s) will have a main fuse, but of course there is NO provision in the three pin plug to house a fuse, due to it's very small size.
I have seen these round pin plugs still used for bed side lamps in hotels etc.
These are protected of course by very low rated MCB breaker, hence no fuse required at the plug top.

 

[johnb80]

The installation of a wallbox can be completely separate from the existing fusebox and wiring. Henly blocks can be fitted to the meter tails, one pair of tails to the existing fusebox and another pair of tails to a new small consumer unit for the wallbox.
The existing house wiring and fusebox should be put on a must do asap list to be safe but adding a wallbox on it's own consumer unit will not affect the existing wiring at all.
In terms of earthing the wallbox, look for a pen fault protected wallbox and you could always drive an earth rod into the ground to be doubly safe. A half decent sparky will be able to do that at minimal cost.

 

[Lovemyev]

The installation of a wallbox can be completely separate from the existing fusebox and wiring. Henly blocks can be fitted to the meter tails, one pair of tails to the existing fusebox and another pair of tails to a new small consumer unit for the wallbox.
The existing house wiring and fusebox should be put on a must do asap list to be safe but adding a wallbox on it's own consumer unit will not affect the existing wiring at all.
In terms of earthing the wallbox, look for a pen fault protected wallbox and you could always drive an earth rod into the ground to be doubly safe. A half decent sparky will be able to do that at minimal cost.

Agreed, this is how mine is wired.
Upgraded the 60 Amp service head via the DNO after they had done their load and supply cable rating checks in order to carry the increased load and agree the increase to a 100 Amp cut out fuse.
Also, a 100Amp double pole isolation switch, the electrician / EV installer split and upgrade the size of the meter tails, install a stand alone CU just to supply the wall box and CPC / Earth bonding upgraded to confirm with the latest regs at that time.
The original house CU remains untouched / intact as a separate stand alone unit.