Provision for Electric vehicle (plus Induction oven)

[Mr.B]

^^^^

I admit that, if the run was through the house rather than through the loft, I was hoping to use twin and earth. SWA would be awkward ... and T&E would be bad enough. But if that's what it has to be then so be it (can I just ask why it has to be SDWA for the entire run and cant just be SWA for the final couple of metres as it goes outside on to the driveway?)

 

[AndyPRK]

T&E cable though the house these days must be RCD protected. (unless surface mounted? or buried greater than 5cm)
And you don't really want multiple RCDs on a circuit. Better to have it at the charger end

 

[Mr.B]

Ah, all is explained. Most certainly didn't realise that to be the case. Ta.

 

[Mr.B]

Andy PRK ... you asked me to post photos of my consumer unit, which I did, straight away .... and haven't had a response to that. I'm wondering why you asked for them?

Have contacted Western Power - they're sending someone to check the size of the main fuse.

 

[AndyPRK]

Sorry. Flameports reply covered it.

As I suspected an electrician may want to upgrade it.
Unsurprisingly its not upto current regulations.
Not all circuits have RCD coverage. It's not metal.

You don't have to upgrade it, but it's probably worth having an all RCBO board fitted.
And before AFDDs become a requirement, which would add another £1000

 

[Mr.B]

^^^^ Thanks for that.

I'm not remotely surprised to learn that, 25 years after it was installed, the CU doesn't meet the standards that a new one requires. The only point in its favour is that it hasn't been interfered with since it was installed (when the house was built in 1996).

I'm old enough to remember fitting consumer units with wired fuses .... they, I'm sure, would warrant an even bigger thumbs down . That was in the day when, after doing the work you would ring the London Electricity Board and they'd send a bloke round on a push bike who would connect your tails and do a 'test and connect' ... and that was that ... no certificates, no nothing.

But moving on from 1969 to the present day, you won't be surprised to know that I had to Google AFDD. I'll let that particular topic remain in abeyance for the time being.

A little bit more head scratching has gone on and I'm still looking to see if I've missed anything regarding where the supply could run - it's not all that straight forward but I'll continue to ponder.

Further thanks.

EDIT. Incidentally, what size are the tails supplying the CU ? I'm rather hoping someone doesn't say they need to be bigger.

 

[AndyPRK]

I would have thought tails would have been ok at that age. But they do appear small in the picture. (To me anyway)

I guess the meter to Cu is quite a distance.

another good reason to take an EV supply from the meter

 

[Mr.B]

Meter to CU is about 2 metres (possibly three ... it's concealed in wall but both are almost back to back on the same wall).

The local office of the DNO just rang - nice bloke, very helpful ... an ex sparks. He could see from the details available to him that it would be an 80 amp main fuse. Same as all the others on the estate, he said.

He reiterated the inadvisability of trying to squeeze a mini CU in a meter cabinet for all the reason mentioned above. He didn't say it was strictly forbidden - just not a great idea in the event that a replacement meter/smart meter was required at some point in the future and, of course, the mini CU might not leave enough space.

If I understood correctly he said an installer of an EV circuit might want to see an RCD in the CU but he said there would be "ways round it" if it were not possible/practical.

That's about it then. Ta.

 

[AndyPRK]

If it’s an 80A fuse the tails should be adequate.

You shouldn’t need the fuse upgrading.

They may want to do something with the earth and bond wires.

I think he was probably wrong about the rcd.

 

[Mr.B]

He did say if I wanted the fuse upgrading to 100 amp it would require an upgrade to the underground cable (at my expense) - but he said it would require exceptional circumstances to want to have 100amp.

Re. the RCD when I look online I can see a variety of references to the need or desirablity or advisability to fit :-
(a) a Type A RCD at the CU end of the run ... or
(b) a type B RCD at the CU end of the run ... or
(c)) No RCD at the CU at all ... or
(d) an RCD of one type or another just at the EV charger unit end of the run.

So that's pretty straightforward then


I did mention that I believed my earth bonding looked like 10mm and he didn't sound alarm bells. But if the earth conductor between gas and electric meter boxes needed increasing it wouldn't be too much of a job as they are next to each other. But I won't volunteer to have it done unless someone tells me it must be done.

EDIT. Having said that I realise I was probably over simplifying the point about the meters being next to each other and it not being difficult to increase the size of the earth conductor :- I should, instead, have assumed that the earth from the DNO's block (see my photo in post #29) goes straight to the CU and then another conductor taken from the CU to the gas meter. A silly mistake. In consequence it wouldn't be quite as simple as I stated .... but IF it HAD to be done it's not a total nightmare. But I'd far sooner it didn't need doing.

In my ignorance I asked what the earthing arrangement was here and he said the property gets its earthing from their cable - i.e. no earth spike. But, as mentioned, I may be showing my ignorance here.

The upshot of all this seems to be that there's considerable room for debate, discretion, divergance and disagreement when deciding exactly what approach to make.

But this discussion has served to enlighten and further inform me (and maybe others who may view the topic) when it comes to asking the right questions of the installer's representatives I encounter - and not to be surprised if, say, I happen to get three companies round to look at the job - and get three very different lots of advice.

 

[AndyPRK]

Supplier provides earth.
Can see PME label near fuse