Tesla Wall Connector - Type B / Type A-EV RCD

[arg]

It was suggested to use 64A cabling just in case I want a second charger in future (minimal extra hardware cost, same labour) - would be happy at this stage to just load share.

I'm all for safety, but this will be running >7' up.

If it's on the surface (all the way), and high up so no risk of mechanical damage, then no need for armoured. If it's concealed behind plaster etc (less than 50mm behind the surface) then armoured avoids the need for RCD protection of the cable. OTOH, armoured is fairly cheap because it's widely used and the expensive bit is the copper which is the same whether armoured or not, so there's not a great saving to be had.

Not quite sure which sizes you are comparing; the normal choice for just a chargepoint is between 4mm² and 6mm², where the 4mm² is only just barely sufficient. In that case, I strongly recommend the 6mm² as it will run cooler and therefore pay back the (small) difference in cost within a year or two by not wasting energy in heating the cable. Going to a still larger size the same effect will be there but much smaller so unlikely to pay back.

Run on the surface, normal ratings are 38A (4mm²), 49A (6mm²), 67A (10mm²), 89A (16mm²). That's at 70C temperature rating; people often use 90C rated armoured cable, but you can't normally use it at the full 90C rating because the equipment you are terminating it to can't take the higher temperature (the place where it is useful is if you have to go through an attic or similar at high ambient temperature - there you can take advantage of the 90C rating in the middle of the cable while still being below 70C at the ends). For reference, the 90C ratings are: 49A (4mm²), 62A (6mm²), 85A (10mm²), 110A (16mm²). Individual cable manufacturers might quote a slightly different figure for their specific cable; possibly that's the source of your "64A".

In addition to the current rating there are voltage drop considerations if the length of the cable run is very long, which may make the smallest possible size not permitted rather than merely inadvisable.

So I'd normally be recommending 6mm² for a single chargepoint; that's got enough slack for some garage lighting/occasional use sockets if applicable, going up to 10mm² if two chargepoints or a lot of other stuff in the garage likely to be used at the same time as charging.

 

[Sirricardo]

TWC in garage charging outside:
I asked my electrician if I could have the tesla charger in the garage, but charge outside by running the cable under the door.
He said that he was not sure this is possible as the earthing scheme required for an outdoor installation (using an earth rod for ground) is different from an inside install (using the houses earth).
Has anyone been told not to charge outside for a garage installation?
He is going to have a chat with tesla about it.

TWC Outside Install:
Also, for the outside install, I think he was saying that to protect the supply cable running outside, an additional box containing the breaker for the tesla charger needs to be outside next to the charger (sounds like an ugly install to me).
Can anyone confirm this has been done on their Tesla charger installs.

Cheers, S.

 

[MrBadger]

If it's on the surface (all the way), and high up so no risk of mechanical damage, then no need for armoured. If it's concealed behind plaster etc (less than 50mm behind the surface) then armoured avoids the need for RCD protection of the cable. OTOH, armoured is fairly cheap because it's widely used and the expensive bit is the copper which is the same whether armoured or not, so there's not a great saving to be had.

So this would save any RCD protection between Henley block at rear of garage and RCD/MCB at front of garage ?

I've asked for a Meter to be installed. Can this be safely installed between (close to) Henley and (remote)RCD - I've seen no mention of MCB or otherwise to protect this, although there is the DNO fuse which would make it exactly the same as the main meter unit.

Do you have a typical price for a Meter? I'm sure the one supplied for my PV was not £100 or so.

I guess the cost of my quote comes down to the cost of the RCD - during visit, the 6mA DC was mentioned, but no mention on quote - just Type A.

 

[arg]

He said that he was not sure this is possible as the earthing scheme required for an outdoor installation (using an earth rod for ground) is different from an inside install (using the houses earth).

The indoor installation can use the PME earth (but is not required to), any case where the chargepoint is likely to be used outdoors is not allowed to. So in principle the case just inside the garage door is just like having it outdoors, and lots of people do that.

The problem comes if the car fits in the garage so you might charge it in there as well as outside, and you have other stuff in the garage (freezers etc.). If there is a reasonable chance of being able to touch both the car bodywork and some other earthed metalwork (that washing machine) on a different earthing system then the separate earth rod for the chargepoint doesn't work. Sometimes that can be resolved by simply switching those 13A sockets to the same earth as the chargepoint. Problem gets really hard with things like washing machines which have plumbing bonded to the house earth, or if the garage has a door into the house so there's nowhere you can put a dividing line between "indoors" and "outdoors".

In that extreme case, you can consider switching the whole house to a TT earth (ie. earth from an earth rod rather than the supplier's earth terminal). That normally needs at least an additional S-type RCD in front of the consumer unit, and needs the whole installation looking at to see that there are no other special cases to be taken care of.

Alternatively, you can use one of the 'magic' chargepoints sold by PodPoint or Zappi which claim to get round the prohibition in the regulations of taking the PME earth outdoors. IMO, those are currently not complying with BS7671 and hence not permitted under the OLEV grant terms (and very marginal under Building Regulations). However, I wouldn't be surprised if their lobbying leads to the regulations being changed.

 

[arg]

So this would save any RCD protection between Henley block at rear of garage and RCD/MCB at front of garage ?

Yes. A normal arrangement for a supply to a detached garage would be just MCB (or, better, fuse) close to the meter, armoured cable with the armour connected to the PME earth at the source end (and insulated at the garage end), then RCD where it enters the garage and mini consumer unit to feed the various circuits in the garage (chargepoint, lighting, sockets), with earth for all those circuits from a rod.

Advantage of arranging the RCD like that (rather than putting it at the source end) is that if you do something in the garage to trip the RCD, you have immediate access to reset it rather than having to walk back to the house and access the meter cupboard. Also avoids having two similar RCDs in series where confusingly both or either may trip on a fault, unpredictably.

However, if the cable is all in view, you are still allowed to do that without the need for armour - it's assumed that people won't drill/nail into cables they can see (though I did once witness some idiot gas fitters where there was a huge armoured cable running along the wall right by the door into the building; gas fitters entered through that door, turned round and drilled a hole through the wall for their pipe right into the cable! Big bang, but the armouring and/or insulated tools saved their lives).

But it sounds like in your case the meter etc. is already in the garage, so I'd expect to put all the switchgear (RCD etc) there and just run the cable down to the chargepoint at the front.

I've asked for a Meter to be installed. Can this be safely installed between (close to) Henley and (remote)RCD - I've seen no mention of MCB or otherwise to protect this, although there is the DNO fuse which would make it exactly the same as the main meter unit.

Do you have a typical price for a Meter? I'm sure the one supplied for my PV was not £100 or so.

Depends on the type of the meter; the little DIN-rail ones that fit in the space of one breaker in a consumer unit won't be rated for high fault current and so must sit behind a fuse/breaker. But even big ones equivalent to the supplier's meter aren't expensive:

Credit Check Meters | Consumer Units Circuit Protection | Page 1 | ElectricalDirect

 

[MrBadger]

But it sounds like in your case the meter etc. is already in the garage, so I'd expect to put all the switchgear (RCD etc) there and just run the cable down to the chargepoint at the front.

The meter is not accessible from the garage (both physically same building as house) as both are only separately accessible from outside - meter cupboard is at rear, garage front and rear but externally locked. So it’s a pain to have to access meter if something trips. Which is why I have asked for mini consumer unit at front of garage but would like meter with the other meters at rear.

That £25 L&G meter is what I have for my PV and was ballpark what I was thinking. But quote says just over £100 inc VAT for meter, and £60 for a IP rated socket. Thought these expensive even if it includes additional labour unless they are special ones. I’m going to go back to them to clarify what bits are going to be fitted.

 

[pow216]

Another good video:-

Features the ”magic” disconnect device!
No Earth rod needed

 

[EVchargersDir.]

This is what I had fitted:

IMG_20190702_121405

• Yev000
• Jul 26, 2019

RCB

that's a type AC RCD, type B MCB, NOT a type B RCD. the B refers to the MCB. Type B RCBO's are a completely different thing thatn a Type B RCD, there is a lot of people making this mistake.

 

[jimbo_hippo]

This surely is the thread of doom I really struggled to get my head around this. However, I believe I have had a breakthrough.

My conclusion is that the regular RCDs we use aren't fit for purpose as they assume the world is AC, there are no particular issue with EVs that make them particularly dangerous.

I half expect type B will be demanded in every installation regardless of EVs or not.

The battery & charger are in the car, the power from the EVSE is AC, rectification happens in the car. There might be a tiny amount of DC in the electronics in the EVSE, but the elephant in the room is 70+kWh of 400V+ DC in the car. If we are worried about DC in the EVSE then we should worry about laptop PSUs, phone chargers etc. the issue of a tiny DC leak saturating an AC RCD would surely confirm that globally all AC RCDs aren't fit for purpose and should be replaced with something new

I have lost 32 minutes of my life to this and won't get it back. The last few minutes are a preview of a clip that hasn't been uploaded

The most staggering thing is this appears to be the last video sparkyninja made on that channel - I sincerely hope he wasn't injured due to a lack of RCD or similar.

Followed by another slating of the "normal" RCDs "The Hazards of AC RCDs" Hilariously it appears the IET have only just noticed we are using electronics in our homes.

23 minutes I won't get back from here:

As far as I am concerned the regulators are late to the party and it looks like EVs are being unfairly framed for an issue that is due to the regulators failing to keep pace with the world.

fullerene..... I had a couple of genuine laugh out loud moments with your post. Just spent 10 mins biting my arm to stop me waking the house with reflex laughter at 2am.

“This really is the thread of doom....” a pie moment of joy in 932 paragraphs of unfathomable electrickery.

 

[smackshaw]

cheapest I found for a Type B RCD, was from EV chargers direct, £114

This is what I've just purchased. Final piece which my electrician will be putting in on Monday. I'll report back.

 

[MrBadger]

cheapest I found for a Type B RCD, was from EV chargers direct, £114

Thanks. Found it here Accessories

The consumer unit looks good - great work btw. Shame about the case though - I think I would have preferred plastic (not sure if it would corrode in garage over a period of time) with a transparent lid so if I got a problem, I could see immediately if something had tripped without having to juggle with a flap and potentially wet hands. But it gives a ballpark price indicator a sparkie should be charging.

Seeing how price of type B's seemed to have dropped, I think I will be insisting on a type B - it sounds better than a type-A + 6mA DC?

I went back to one installer as whilst he spoke of Type-A + 6mA RCD, his quote only mentioned Type-A. Not heard a peep out of him since I queried this. The above pricing makes his quote look even more expensive.

 

[EVchargersDir.]

thanks for your reply, new consumer units fitted in the UK now have to be metal not plastic, for fire safety. its included in the wiring regulations.

 

[arg]

thanks for your reply, new consumer units fitted in the UK now have to be metal not plastic, for fire safety. its included in the wiring regulations.

Only in houses. In a detached garage for example, plastic is still permitted. It is also permitted to enclose a plastic one in a non-combustible enclosure, which is not normally cost-effective but could be if corrosion is likely to be an issue.

 

[smackshaw]

This is what I've just purchased. Final piece which my electrician will be putting in on Monday. I'll report back.

It's been in a week and I'm happy to report everything is great. Car charges at 32A without fault. The only downside is it's width as it's designed for 1 Phase and 3 Phase electricity. Still, just squeezed in my consumer unit but no spare slots now.

 

[MrBadger]

If having a new dedicated consumer unit in garage added, does this need to be 'surge protected'? I've had two sparky's mention this now.

Personally I don't like the sound of the surge protection - seems like it would be activating very often and blowing the fuse if it works as described.

Sounds like its a separate unit to the consumer unit. Im planning on going with this CU from EV Chargers Direct.

Also, latest sparky talked about XLPE SWA cable as he may be able to go down a size.

 

[Glan gluaisne]

Surge protection is probably a good idea, IMHO, as we seem to have more and more kit that's susceptible to voltage spikes. A friend had their heat pump controller knocked out a week ago, following a power cut, and I strongly suspect the cause was a spike, that may well have been mitigated by a SPD.

A stand-alone surge protection board is around £70, but has to go right at the incoming supply, as cable length is critical. If my friend had one of these she'd probably not have incurred the bill for ~£600 for a new controller board for her heat pump. Needless to say, her installation now has an SPD fitted.

As for going down in size when using XLPE SWA, I'd not do it, because of the power loss. In theory, I could run one of my 32 A charge points on 2.5mm² SWA, as the cable is buried and only about 4m long. It would be a daft thing to do, though, as the cable would lose ~100 W, so although it might not overheat, it would get pretty toasty, too toasty for the terminations, I suspect.

Cable is pretty cheap, and a heavier gauge cable will soon pay for itself in reduced power loss.

 

[MrBadger]

But is surge protector needed in the regs?

Its 63A over ~10m so its either 25mm or 16mm. The concern seems to be more the workability than the cost.

 

[Glan gluaisne]

But is surge protector needed in the regs?

Its 63A over ~10m so its either 25mm or 16mm. The concern seems to be more the workability than the cost.

No requirement to fit an SPD AFAICS, they are primarily a "nice to have" device to prevent damage to stuff in the event of a fault, lightning strike etc.

As for power lost in the cable, then 16mm² has a voltage drop of about 3 mV/A/m, 25mm² is about 2 mV/A/m. Not enough to be worth worrying about in power loss terms.

 

[arg]

Surge suppressors are now in the regs, though you can usually do a kind of risk assessment to show they aren't mandatory.
I'm rather unconvinced by this philosophically - BS7671 is normally cited as a safety specification, while this is purely a matter of economic impact. Poorly-designed surge arrangements are often ineffective or in extreme cases actually make things worse. And also, CE-marked equipment ought to have on-board surge protection to comply with the EMC directive (though of course no-name imports might not). So IMO if you are out in the sticks with supply on overhead cables then whole-house surge protection is worth thinking about; otherwise I'd aim to avoid it.

On the SWA ratings issue, usually you can't take advantage of the extra rating of the XPLE cable for the whole length, because the higher rating is down to running at higher temperature (90C vs 70C) and if you are rating the cable for 90C the equipment at each end you are terminating it on also needs to be rated for 90C, which it usually isn't. The one case where XPLE is particularly useful is if you have somewhere on the middle of the run with more restriction - like it has to go through an attic with high ambient temp or behind insulation etc. - so you can use the 90C rating in the middle to avoid de-rating and just the 70C rating on the ends where it's in open air.

Still, for your case 16mm² already has a 78A rating (buried) or 89A (on a wall) even in the 70C table, so it's hard to see why 25mm² would be needed.

 

[SickJim]

What about £232.88
Schneider Electric A9Z51240 40A Single Phase 2 Pole 30mA Type B RCD
Schneider Electric A9Z51240 40A Single Phase 2 Pole 30mA Type B RCD

Or £145
Type B RCD / RCCB 80amp for EV Charge Point Installations. 4 pole, 3 phase or single phase, 30ma

Type B RCD / RCCB 80amp for EV Charge Point Installations. 4 pole, 3 phase or single phase, 30ma.