Is RCD protection required on SWA supply cable to EV?

[Brownie91]

Hi all,

I am at odds on whether RCD protection is required on an SWA of 14 metres, clipped direct under flooring direct from CU to an exterior Tesla EV charger.

The Tesla charger is three phase and to be a 22kw supply at 32A.

TESLA SPEC: The wall charger itself features a built in RCD Type A + DC fault protection at 6mA. AC earth fault interruption automatically detects an AC current mismatch between power delivery conductors that would indicate current is flowing through the earth conductor. AC fault protection will trip at 20mA. DC earth fault interruption automatically detects DC leakage through earth.

After looking in the regs book (reg no 722.531.3.101) my understanding is that this would not require an RCD on the supply cable and fed via an MCB at the main house consumer unit (TN-C-S system)

I would love to know your thoughts on this as I have had advice suggesting both. I did speak with NICEIC as they implied it was a grey area much to my surprise!

Any feedback would be greatly appreciated

Ryan

 

[James]

I don’t see why it’s a grey area.
Assuming disconnect time can be satisfied without an rcd, swa would not require rcd protection.
The device has an rcd device so the load is protected

This is not much different to an rcd socket supplied by swa from an Mcb.

 

[Brownie91]

I don’t see why it’s a grey area.
Assuming disconnect time can be satisfied without an rcd, swa would not require rcd protection.
The device has an rcd device so the load is protected

This is not much different to an rcd socket supplied by swa from an Mcb.

Agreed. They seemed to suggest as the Tesla unit doesn't have an RCD test button it may require RCD on the supply cable but didn't really give me a definitive answer on it. Although Tesla states unplugging clears any faults the internal RCD protection.

 

[westward10]

Is ADS satisfied without an RCD.
As above it is not a grey area.

 

[Julie.]

There is a bit of a grey area.

Providing the EVCP has an integral rcd to BS EN 61009 then a mcb should be acceptable upstream with armoured cable.

However, some EVCPs have a proprietary rcd, not compliant/proven with/to BS EN 61009, in which case a compliant rcd will need to be fitted.

The issue is the wording of 722.531.3.101 which appears to mandate a rcd on the circuit - but it actually does allow for a rcd within the EVCP but before the socket outlet or bs 62196 connection

 

[Markyd]

Worth a watch

 

[Julie.]

Worth a watch

Yeah I can't understand why it's necessary to fit one here - and said as much in the comments to the video, quoting the same reg as I stated above.

The regs haven't changed that much at all in the respect of the rcd, just different wording for essentially the same thing.

I think they may be trying to pull a fast one on the customer and therefore whoever fitted their EVCP

Perhaps they changed their product to no longer have an rcd, or just B.S. their way into a free install of their warranty replacement.

 

[Brownie91]

There is a bit of a grey area.

Providing the EVCP has an integral rcd to BS EN 61009 then a mcb should be acceptable upstream with armoured cable.

However, some EVCPs have a proprietary rcd, not compliant/proven with/to BS EN 61009, in which case a compliant rcd will need to be fitted.

The issue is the wording of 722.531.3.101 which appears to mandate a rcd on the circuit - but it actually does allow for a rcd within the EVCP but before the socket outlet or bs 62196 connection

Thanks for the reply Julie.

Its grey indeed. I have been going through my old notes from an EV course and almost certain the upstream RCD would be required on a PME system. Not a TNS (which is the system I am installing on). ANOTHER grey area being a TNS should be treated as a PME as its possible there could be a join elsewhere from the PME-TNS before the dwelling entry & also if it could change over in the future. I personally don't see an issue, after verifying the system is indeed TNS, not installing an RCD and issuing a note on the consumer unit/certification that any changes to the earthing supply the EV supply would need to be reviewed.

But again, maybe its just worth putting it in to be sure. It's going to cost a lot more than expected as fitting the RCD somewhere is not simple. If it was straight forward I would no doubt be putting one straight in.

 

[Julie.]

Thanks for the reply Julie.

Its grey indeed. I have been going through my old notes from an EV course and almost certain the upstream RCD would be required on a PME system. Not a TNS (which is the system I am installing on). ANOTHER grey area being a TNS should be treated as a PME as its possible there could be a join elsewhere from the PME-TNS before the dwelling entry & also if it could change over in the future. I personally don't see an issue, after verifying the system is indeed TNS, not installing an RCD and issuing a note on the consumer unit/certification that any changes to the earthing supply the EV supply would need to be reviewed.

But again, maybe its just worth putting it in to be sure. It's going to cost a lot more than expected as fitting the RCD somewhere is not simple. If it was straight forward I would no doubt be putting one straight in.

Well some aspects of the "grey" area are actually very clear, 722.531.3.101 in simple terms mandates that a compliant RCD is fitted before the connection to the vehicle.

It is irrelevant as to TT, TN-S, TN-C-S or PME, so the earthing arrangements have no bearing on the need for a RCD. (Although do impact other areas)

The real grey area is, if the EVCP does have a RCD - is this actually a compliant one?

For example the (old) rolec ones have a standard type A RCD to bs 61008 with the reset/test available to the user. Therefore an upstream RCD is not required. (But overcurrent is.)

But, is the one in the zappi/podpoint/whatever EVCP compliant? - do we know? - do the manufacturers actually state "this EVCP contains a RCD which does not meet acceptable standards....." - err no!

That's the grey area, to me it's appalling - they all advertise their kit as compliant, yet some require additional protection externally as their included protection isn't actually compliant - and they don't tell us!

Worse still, if we add an additional RCD upstream of their integral RCD; we now have two in series, with likely both tripping, how can a user reset this?

After all, the fault is likely to be within the vehicle charger itself, another vehicle won't have this same fault, so we should be able to reset the EVCP easily - ideally at the EVCP, (not crawling about in both the consumer unit and the innards of the EVCP)

 

[buzzlightyear]

Its grey indeed. I have been going through my old notes from an EV course and almost certain the upstream RCD would be required on a PME system. Not a TNS (which is the system I am installing on). ANOTHER grey area being a TNS should be treated as a PME as its possible there could be a join elsewhere from the PME-TNS before the dwelling entry & also if it could change over in the future

That was my saying not long ago about
TNS to PME system. I would be nice you can ring up the DNO, will the systems being up graded, there is a lot of sparks
Still puting in EV chargers on TNS that don't require a up front rcd or a Rcbo
Because the charger has built in devices.
Their is a lot of customer won't up grade to smart meters, but they will put in EV's.