RCD protection of mode 3 charger

[PeteRig]

Interested in feedback about mode 3 car chargers with RDC-DD an a type A rcd in the charger.

We questioned the manufacturer about this, their comments below:

They are calling their pedestal charger a switchboard, if so it should have a MEN link if a charger is supplied from this so called switchboard, as per WorkSafe guidelines and EWRB Electron 124

Manufacturers comments:

"I agree that it is clear that a Type A RCD has to be included in the final subcircuit as per the WorkSafe guide to installing EV charging stations (when the charging stations have RDC-DD / 6mA DC leakage protection)
What we call a pedestal is just a frame to house an electrical junction box (as you will read below any electrical junction box with circuit protections is considered a switchboard) an isolator and two charging stations. This takes a larger single phase supply and separates it into two separate final subcircuits for each Wallbox.
From the document that you provided
1.4.88 Subcircuit, final
A circuit originating at a switchboard and to which only consuming devices or points will be connected. The origin of a final subcircuit is deemed to be at the connecting devices of the neutral bar or link or at the load terminals of the circuit protective devices provided within or on a switchboard specifically for the connection of the circuit. The termination of a final subcircuit is deemed to be at the supply terminals of consuming devices or points.
There is no difference if a larger supply cable was run across a building to a switchboard / distribution board / load centre / Junction box with RCBOs / whatever other name we can come up with, and then supply charging stations on a wall.
The reason we have made it this way is to be able to use underground distribution. Above ground distribution normally uses single pole RCBOs that overheat / burn when placed directly next to each other with no air gap, and placing a switchboard somewhere in a car park where it won’t be hit results in long cable runs, and we have seen many when the installer has completely forgotten to factor in volt drop.
I am confident that we cover off the requirements of ESRs / Worksafe, and developed the system having first had a meeting with worksafe to conform we were on the right track (back in 2018) We do always take on board feedback from people such as yourself however, and If you can point out what you don’t agree with I will ask for clarification. Also, give me a call if you would like to discuss in more detail.
Below is some feedback that I have had with questions relating to switchboards / junction boxes
When it comes to definitions, the primary term is "switchboard.
Defined 1.4.121 of 2018 +A1+A2+A3
sub-classes main switchboard" [1.4.122] and "distribution board [1.4.46].


Within ESRs, there's another sub-class : "MEN swbd".
defined in ESR 4, and only applicable in context of ESRs.

So,
Q: What is the difference between a ‘switchboard’ and an electrical junction box that has circuit protection in it?

A1: Absolutely nothing. If there is circuit protection for one or more final subcircuits or submains; then it's a swbd.
Regardless of what other functionality may also be incorporated.

A2: There is one case where it can be argued that an over-current device is not "circuit protection" and so does not create a "swbd".
That's when there is a reduction in CCC part-way along a circuit, and 2nd part of 2.5.1.3 requires over-load protection in addition to the protection at origin of circuit.
There's a protective device, but it's not protecting an (entire) circuit - only part of the circuit.
Prime example being swbd feeds tee'd off rising (sub)mains; where Exceptions to 2.10.1 have the effect that the overcurrent devices for the smaller conductors don't have to be in a swbd.
However while that interpretation may work in the case of no branching, or even where a up to 2 smaller branches are tee'd off from a circuit in larger cable ;
it won't work where you (presumably) have a single supply in ( ie a submain), and multiple over-current devices protecting final subcircuits out to EVSE points.

The only combination I'm certain can't be called a swbd is where the tee'd-off smaller cable doesn't actually have an over-current device, but instead relies on the inability of the connected load to impose an overload [2.5.3.4(b)(ii)].

One of the issues to be dealt with in coming Revision is "swbd" vs "control panel".
However when someone calls their unit a "control panel" it's often not because it isn't a switchboard; but rather because they don't want to comply with one or more of the rules for "swbds". Eg access / egress.

Can't be certain how that will pan out, but i believe that as long as we can deal with the semi-related issue of demarcation between
- equipment that is part of the "installation"; and
- equipment that is supplied by, but not part of, the "installation";
then the rest will fall into place.

Bottom line: everything is "equipment" (undefined term).

But, we make a distinction between "installation wiring" [1.4.12]which must comply with "the appropriate requirements of this Standard",
and "equipment wiring" [1.4.131] which - by implication, but not stated, doesn't.

Also Internal wiring of a swbd is stated to be "equipment wiring", in specific context of 3.8 [Note to 3.8.1];
which conveys that the requirement of 3.8.1 to ID conductor function does not apply

All of which leads people to think that other aspects of Wiring rules similarly don't apply to "equipment wiring".
However the only requirement that we absolutely know doesn't apply is conductor ID.

So your assembly is intended to accommodate circuit protection for final subcircuits.
Often assumed that "circuit protection" means over-current protection, but that's just interpretation not fact.
I can see nothing to persuade me that "additional protection" is excluded from be "circuit protection.
Especially when it is specified [2.6] is something applied to subcircuits

As supplied (ie no RCBOs) it is technically not a swbd.
But as soon as the first device is fitted, it certainly becomes on.
Exactly the same as any domestic or similar swbd enclosure.

If being manufactured as a swbd, should conform to "61439"

But - as per the opinion - could be assembled as PEW, with a CoC issued
There are 2 pathways to compliance for a switchboard.
One is manufacture, as you say this would normally be to a relevant Standard; and the result is an entity called "switchboard"which is then installed into an installation as PEW.
The other is assembling it as PEW; treating the enclosure(s) and each fitting within individually.

If assembling as PEW; the work is done by licenced person(s) and the work is included on a CoC.
If manufactured, there should be some sort of documentation asserting compliance.
2018 edition of "3000" provides guidance WRT compliance documentation in an Appendix.

However regardless of which of these pathways has been followed; responsibility for safety of the switchboard once installed into an installation rests with the certifier.

Important to recognise that switchboards are not required to comply with a particular Standard.
They are not DMRAs or DHEAs, so no SDoC or Approval is required by ESRs.
What they have to comply with is the relevant clauses of "3000" - most but not all of which are in subsection 2.9.

Under currently-cited edition of "3000" (2007 +A1 +A2); subsection 2.9 does call up "3439",
but this "secondary citation" is non-mandatory except for one aspect.
2.9.3 "construction (of switchboard)"; 2.9.3.2 "suitability"; says that switchboards complying with the relevant requirements of "3439" are deemed to comply with 2.9.3 . Not that construction of the switchboard must comply with the Standard; just that a switchboard that does comply with (constructional) requirements of "3439" is recognised as complying with 2.9.3.

2.9.3.3 then goes a step further, by requiring clearance & creepage distances to comply with "3439 series".

So, at minimum, you either check it yourself; or you seek documentation that satisfies you that the switchboard complies with 3439 in general,
and in particular that creepage / clearance distances comply.

Under 2018 edition; situation was similar, though also citing "61439" series as alternative.
Then Amendment 2 set a "trigger" condition such that switchboards either above a specified current rating, or above a specified PFC, must comply in full; whereas below the trigger level only some particular aspects must comply.

A3 then deletes almost all references to "3439 series; leaving "61439 as the only recognised manufacturing Standard for new switchboards
This is because "3439 series has been withdrawn; so is no longer being maintained.

This may mean that re-using an old switchboard that was built to an earlier Standard is likely to be non-compliant.
Which mostly only affects construction sites and show / carnival "temporary" installations; however in some cases such switchboards can be re-certified - by the original manufacturer - to the new Standard. Re-certification by a 3rd-party test lab could also be done ; but with significant cost.

Regardless of what documentation you may have, it's still the certifier that signs-off the safety of the switchboard.
And the documentation won't cover all aspects of switchboard compliance; it's only, or largely, about construction of the switchboard;
the installer still has to ensure other aspects as per rest of 2.9 (and any other requirements of "3000") .
That said; I'd expect a reputable manufacturer's product would comply with eg 2.9.4, 2.9.5, & 2.9.6."

[AlecK]

I suspect I am the source of the answer being quoted here

Perfectly possible to have an EV charging station that includes a switchboard.
And yes there could be good afr doing so, especially in a commercial environment.


In that context; we need to look at what the applicable documents has to say about supply to EVSE
worksafe Guidelines:
The addendum published Oct 2019 states [item 3, bottom of page 1]:
3. Where an EVSE is installed at a residential installation, the charging final subcircuit shall be protected by a type B RCD and the subcircuit
shall originate from a MEN switchboard.
(Not sure there's any real safety basis for this)

3000:
Clause 7.9 of "3000:2018" prohibits use of an outbuilding MEN
(Not sure this prohibition can be justified either, but it's there)

Remembering the neither of these documents is mandated yet.
But following all available guidance for a residential / domestic installation, then the final subcircuit has to come from a MEN swbd.
and it can't be one in an outbuilding

Under current requirements, we are not allowed multiple MEN switchboards within same installation (any type) except using the outbuilding provisions.
That's not a direct prohibition; more a result of the requirement that PECs must not carry load current under normal conditions.
Which precludes having any N-E links downstream of the MEN link at MSB; unless using the special provisions for an outbuilding supplied via a PEN submain.
We used to be allowed to do this, and then from 1993 we also had "linked busbar swbds" as a third type.
Those can remain in service [ESR 113], but under current edition of "3000" we can't install any new swdbs with links except as outbuildings

So no problem under the Guidelines setting up an EV station as an "outbuilding", provided it is an actual outbuilding as defined.
Eg, must be physically separated from the building that supplies it.

Except Clause 7.9 specifically prohibits doing this .
So in effect the final subcircuit for residential has to come from the MSB .
But for non-residential there's no "supply from MEN" requirement, so can set up the charging station as a DB, supplied by submain including a PEC

From the somewhat limited info here; I suspect this charging station would be very suitable for a non-residential installation.
But may be difficult to make it comply with both the Guidelines & Clause 7.9 in residential.


I expect that Clause 7.9 will be changed in coming Revision.
The "not from outbuilding" rule may well vanish
The current wording was put there by Worksafe, but that was some time ago (published 2018); and things have moved on a bit.
That's why there have been several updates to Worksafe's Guidelines.

Whether the Guidelines may also change, eg to remove the "from MEN in domestic" rule, is up to Worksafe.

Certainly there will be increasing demand for multiple EVSE in residential installations.
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[PeteRig]

Thanks Alec, not sure if you were the source of the answer from the manufacturer (dont want to name the manufacturer)

So these charging stations are in a non-residential environment, so the question is, is a RCD required at the switchboard supplying the pedestals (free standing by the kerb)? Reading your reply, it is not if the EV chargers are set up as switchboards (even if there is no MEN link).

Good to get clarified, maybe WorkSafe could write something clarifying this one day.

Thanks

[AlecK]

A freestanding pedestal type structure would conform to definition of "outbuilding".
And in a non-residential installation,
- the Guideline requirement to take supply from an MEN swbd would apply; but
- the Clause 7.9 prohibition on supply from an outbuilding would not apply.
So if arranged with PEN submain to pillar containing MEN swbd; the final subcircuit would start at the swbd in pillar and end at the EVSE section , being completely within the pillar / pedestal.

The RCD requirement is that the final subcircuit must be protected.
That could be done at origin of submain, but better done at origin of FS .
For a single charge point, makes little difference.
But for 2 or more, protecting each FS separately avoids unwanted disruption to one circuit caused by fault on other circuit.

[PeteRig]

Thanks Alec, I don't believe the charger in question has an MEN therefore an MEN needs to be installed in the charger switchboard (complete with an earth electrode?) or an RCD installed at the origin of supply to the charger, to comply with the guidelines, correct?

Another scenario, a mode 3 charger (not on a pedestal) in a non-residential situation, the charger has a switchboard with a MEN, can this charger be installed on an outside wall or inside a building that already has a MEN switchboard, what happens here?

[AlecK]

1 Yes, an "MEN switchboard as defined in ESR 4 must be connected to an earth electrode.

2 3000 doers not permit more than 1 MEN swbd within same installation; except for an outbuilding.
so correct can have a freestanding pedestal (as outbuilding), but not a "EV swbd" mounted in / on same building as installation main swbd.

3
All the above would be for building(s) containing a single installation.
When we get to multiple installations within same building (eg block of offices), each will have an MEN MSB.
but (these days) none of them can have a MEN DB.
The 'rising mains' tapped off to feed all those MSBs, isn't "mains"; but actually (private) "works"
Life gets tricky just with that- especially for existing stuff installed long before today's Wiring Rules came into effect.
So i don't want to even try to work through the extra complications of adding EVs.