Consultation on Electric vehicle (EV) chargers for residential applications (DZ 6011:2020) closes 22/01/2021

Forums › Transport (cars, bikes and boats) › Consultation on Electric vehicle (EV) chargers for residential applications (DZ 6011:2020) closes 22/01/2021

cthombor

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#280587 26-Dec-2020 12:04

Standards NZ is currently consulting on draft PAS (publicly available standard) DZ 6011:2020 to provide "advice and information to New Zealand consumers on the charging of electric vehicles (EV’s) at residential premises." Consultation closes 22 Jan 2021.

It's a very important and timely topic IMHO, so I'm hoping they'll get some constructive feedback -- please consider doing this yourself! I'm planning to submit.

I'm a newbie on this forum so am not allowed to post hyperlinks, apologies for the inconvenience.

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#2626896 26-Dec-2020 12:47

16A minimum, cable to 32A to allow retrofitting higher later. And raises the possibility of car to grid and using car battery as house battery.

Ideally I'd say 32A line but that's a large amount of current compared to total current doing into house but see above

EV circuit should be isolated from rest of house circuits.

Some sort of safety guidance about placing charge point outside vrs inside garage.

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SomeoneSomewhere

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#2626905 26-Dec-2020 13:21

Whether a type B RCD remains necessary if hardwired EVSE already includes one natively...

cthombor

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#2626938 26-Dec-2020 15:36

While preparing to submit on the SNZ Electric vehicle (EV) chargers for residential applications consultation (DZ 6011:2020), I read through the May 2019 2nd edition of Worksafe's Charging Safety Guidelines.

In my understanding, these Guidelines have made it illegal to supply -- and perhaps even to use on a regular basis!?? -- any IC-CPD (Mode-2) charging-cords for EVs.

See clause 1.7 b, quoted below: the "IC-CPD" device on these cords should interrupt the supply of AC power to the EV, automatically, if the grounding pin on their power source isn't connected to earth.

Well... this is an absurd requirement -- AFIK it can't be met (see below).

If I'm correct about this infeasibility, then... WorkSafe's requirement for a ground-fault-interrupting system has effectively outlawed mode-2 charging equipment in New Zealand! That can't be a good thing for EV owners, or for EV suppliers, or for our nation's ability to meet its carbon-reduction targets... but nevermind all that, WorkSafe's brief is to save lives.

And... mode-2 charging is indeed hazardous if the grounding pin on its power supply isn't connected to earth. If you lean on the car while it's charging, you *might* conceivably get a fatal shock. Furthermore a ground-loop *might* cause an excessively-high power consumption which wouldn't trigger the RCD (if any!) on the AC supply to your mode-2 charging cable. Anyway: an RCD doesn't fully protect against ground-faults.

What's really required (IMHO) for a best-faith "reasonable" conformance with this infeasible-to-meet WorkSafe requirement on mode-2 charging in personal/residential situations is a one-off confirmation (by a registered electrician) that the ground-pin on the AC supply-point for a mode-2 charging cable has a very low-resistance connection to earth ground. Given that many power outlets in NZ would fail such a confirmation, I'm thinking it would be appropriate to have Standards New Zealand issue a labelling standard for residential AC power outlets -- so that a registered electrician could affix an "Safe for EV charging" label and a "safe use" explanatory booklet to their residential client, after repairing any earth-fault or current-supply defects in that outlet (which can have only one socket, and which must be on a dedicated circuit).

Do you agree? If so (or if you have any other concerns about residential charging of EVs in NZ), please consider making a submission on the DZ 6011:2020 consultation (open until 22 Jan 2021) by Standards New Zealand on "Electric vehicle (EV) chargers for residential applications". And if you disagree, or have questions... please post here!

--

Below: some technical blithering which may be of interest...

According to the May 2019 2nd edition of Worksafe's Charging Safety Guidelines, the maximum power that can be supplied to any of mode-2 charging cables that are currently supplied in NZ depends on its power-plug. If it has the usual 10 A plug, then you can charge at up to 8 A. If it has the 16 A blue plug that's normally used on caravans, then you can charge up to 12 A. (There are a couple of other possibilities: a 15 A charging cable with a 20 A plug, and a 10 A charging cable with a a UK-style 13 A plug.)

The de-rating specified by WorkSafe will significantly reduce the likelihood of overheating of the plug during a multi-hour charging session... but it won't entirely mitigate this risk! I think it'd be important for all EV owners to be notified (verbally by their sparky when one of their outlets is certified "Safe for EV charging", and also in writing in a booklet published by Standards New Zealand), that plugs *do* overheat when their pins or sockets are corroded, and that anything more than a slight warming is quite a worry -- they really should consult with a sparky before their next use of that outlet or mode-2 charging cable.

Well... of course, if you want to drive your EV more than 80 km per day, you'll want to charge more rapidly than the 8 A (1.8 kW) rate that'd be safe on a 10 A "Suitable for EV charging" outlet! If you'd have to pay a sparky to fit a 20 A socket on a dedicated circuit, you'll maybe go the additional expense of purchasing a mode-3 EVSE and have the sparky install it, but!

AFAIK, very few of the mode-3 EVSE chargers that are currently for sale in NZ have continuous earth-fault monitoring -- and I am not at all sure there's much WorkSafe-compliant kit available worldwide. NZ is nowhere near large enough a market for its regulatory stance to have any impact on the product design of major manufacturers of EVSE... making me concerned that WorkSafe has over-regulated here.

At a rough estimate, an earth-fault relay and its control circuitry adds hundreds of dollars to the cost of a mode-3 EVSE. Someday, perhaps, this particular requirement (for "continuous" monitoring, rather than a single check when the charging cable is first connected to the vehicle, or a periodic monitoring at say hourly intervals as in IEC 61851-23 for fast-charging DC EVSEs) will be covered for mode-3 (AC) chargers in the IEC 61851 standard... but... I suspect *that'd* be a complicated and contentious revision to IEC 61851, given the variety of earthing systems in use worldwide (or even in the UK), and given the (usual) debates in standards-committees between manufacturers who want to gain a competitive advantage by having a compliant product versus those manufacturers whose products lack the compliance feature currently being debated... But hey I really can't predict what the IEC will do! I'm not an electrician! I'm just an EV-using consumer who happens to know enough about electronics, electrical safety, some of the (many!) relevant standards, and the processes of regulation-drafting & standard-making to be very very concerned about the way things are heading in NZ with residential EV charging...

What (I wonder!) are the relative likelihoods of an electrician-installed EVSE's earth-connection being lost (e.g. through somebody doing something that disconnects a residential earth-connector from its copper-stake-in-the-earth), the WorkSafe requirement for a continuous earth-fault interruption system on EVSEs being widely ignored? What is the total additional cost (multiplied by all residential EVSE installations in NZ) of requiring continuous earth-fault monitoring? How many residential-electrical fires are likely to be caused, annually, if WorkSafe's current regulation is relaxed (or widely ignored)? How many insurers will refuse to pay on a residential-fire claim that was caused by the use of a non-compliant mode-2 or mode-3 charging of an EV?

So... I think it pretty important EV owners, and anyone concerned about NZ's ability to reach its greenhouse-gas reduction targets, push back against what (IMHO) is an overstep by WorkSafe. Yes, they can (and IMHO should) insist on continuous earth-continuity monitoring on EV chargers in public places, and also in workplaces -- but a certification process which *checks* domestic wiring for its earthing integrity would I think save many more lives than (as at present) making it impossible to legally supply mode-2 charging equipment in NZ.

Automated continuous earthing-confirmation systems have (I'd guess!) been required on high-current commercial supplies for many years by WorkSafe; but the relay alone costs at least $1000, and it must be installed by a registered electrician.

if you tried to build one of these earthing-confirmation systems into a mode-2 charging cable assembly, you'd need to add an earth-ground connector. You'd have to rely on the end-user connecting its earth-ground connector to something (such as a copper rod pounded deeply into the ground) which is reliably connected to earth. Yeah right, like that'd ever happen! Instead the usual number-8 workaround (I'm sure!) would be to connect the IC-CPD's earth-ground connector to a ground-pin on the very same power-outlet that is sourcing its power -- thereby transforming the use of this (quite expensive!) cable into a performance of "safety-comedy theatre" in which only a naive spectator might believe there has been an actual improvement in safety rather than yet-another casual everyday defeat of a well-intended but practically-infeasible safety regulation ;-)

Quoting from the May 2019 2nd edition of Worksafe's Charging Safety Guidelines:

1.7 General requirements for In-Cord Control and Protection Devices

All In-Cord Control and Protection Devices should:

a. incorporate an RCD function to provide protection against electric shock

b. incorporate or provide a system that continuously monitors earth continuity and automatically disconnects the supply in the event that the earthing connection becomes ineffective

c. provide protection against the overload of the charging supply fittings

d. provide protection against the overload of the incoming supply fittings, and

e. be designed to operate at standard low voltage and a nominal frequency of 50 Hz and marked accordingly.

All functions of an IC-CPD should fail to safety.

Any person supplying IC-CPD should have, and must make available to WorkSafe on request a Supplier Declaration of Conformity, and either:

a. in respect of IC-CPD complying with IEC standards, the relevant test reports and certification or approvals, or

b. in the case of IC-CPD complying with UL standards, the relevant verification of UL certification.

Any person supplying IC-CPD should have and should make available a Supplier Declaration of Conformity on request by a purchaser or potential purchaser.

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#2626949 26-Dec-2020 16:38

Haven't read the above in full, but my understanding is that earth continuity testing has been part of EV charging for some time, So I don't think requiring it would outlaw Portable charging cords.

In order to charge an ev from a generator this must be defeated by a earth to neutral bridge.

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#2626958 26-Dec-2020 16:49

Automated continuous earthing-confirmation systems have (I'd guess!) been required on high-current commercial supplies for many years by WorkSafe; but the relay alone costs at least $1000, and it must be installed by a registered electrician.

if you tried to build one of these earthing-confirmation systems into a mode-2 charging cable assembly, you'd need to add an earth-ground connector. You'd have to rely on the end-user connecting its earth-ground connector to something (such as a copper rod pounded deeply into the ground) which is reliably connected to earth. Yeah right, like that'd ever happen! Instead the usual number-8 workaround (I'm sure!) would be to connect the IC-CPD's earth-ground connector to a ground-pin on the very same power-outlet that is sourcing its power -- thereby transforming the use of this (quite expensive!) cable into a performance of "safety-comedy theatre" in which only a naive spectator might believe there has been an actual improvement in safety rather than yet-another casual everyday defeat of a well-intended but practically-infeasible safety regulation ;-)

I don't think you understand what you're talking about. For starters, an earth electrode is generally speaking not the type of earth ground the standard is talking about. Earth electrodes cannot carry useful fault current.

Generally, they verify that the MEN link is present by ensuring earth and neutral are connected together without tripping any RCD. I believe UL-certified solutions already require this as they exclusively use TN-type earthing as we do.

Compare with the UK solution which appears to require a separate TT supply for the charger including a dedicated earth electrode which must be driven with clearance from any other underground services.

It looks like ABB's product has earth-loss monitoring although it does not state how frequently this is checked. There is no real reason it can't be continuous.

cthombor

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#2627021 26-Dec-2020 20:53

Thanks for the clarification! I think you're right, as an IC-CPD could reasonably be expected to perform continuous MEN-link testing -- if this was what it was designed to do... but I'm not at all confident that all (or even many) of the IC-CPDs currently in NZ are doing this, and if not then this would become quite an onerous (and novel) requirement on anyone who imports a used EV from a jurisdiction which hadn't been requiring MEN-link testing on its IC-CPDs. (Having all IC-CPDs perform such a test -- and refuse to charge the EV if the test fails -- would only make sense in a region which has only MEN-earthing and not any of the other earthing systems.)

My current *guess* as to WorkSafe's intended meaning of this requirement is that the EV charging must stop if the CP circuit is opened. (There's a resistor between the PE and the neutral in the Type 1 or Type 2 plug on a mode-2 EV charging cable, this is what closes the CP circuit.) This requirement is easily met, and I'd *hope* that all IC-CPDs do indeed stop charging immediately the CP circuit is carrying either too much or too little current. (I have seen a note in Wikipedia suggesting that J1772 allows IC-CPDs to step back to Type-1 charging -- at 16 A max ! -- when CP becomes inoperative. Well I *hope* that's only a disused allowance in the J1772, because a IC-CPD that will perform Type-1 charging (even with a red warning light flashing) is certainly *not* something I'd want to ever see in NZ!)

cthombor

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#2627028 26-Dec-2020 21:40

On to another question regarding IC-CPDs in NZ, and to another question I have about DZ PAS 2011 that I'd like to discuss (at least briefly) before I submit on it:

Are any (or all!) IC-CPDs in NZ continuously testing whether the ground-pin supply never has much of a voltage drop to its neutral-pin supply? This is (very roughly) what an RCD does... and I suspect it's the reason why RCDs are sometimes marketed (e.g. by PDL/Schneider) as "Earth Leakage Circuit Breakers". The WorkSafe requirement to "incorporate an RCD function to provide protection against electric shock" is in addition to the requirement to continuously monitor "earth continuity"... and...

I don't see an RCD label on any of the (3!) IC-CPDs I own. All do carry a notice warning that it should only be used with a power source that has an RCD breaker. That lack of RCD label, I believe, puts them all out of compliance with WorkSafe -- and once again I'm wondering if they're over-regulating. Yes you have to be careful to use a more-sensitive RCD downstream of the RCD-a on a circuit board... and life would certainly be simpler for everyone if all IC-CPDs had an onboard RCD that was appropriately specified for being downstream of an RCD Type A... but in the world I live in, I'm almost certain that none of my IC-CPDs have such an RCD.

DZ PAS 2011 at page 32: "All EVSE circuits for mode 2 or mode 3 charging in a residential installation should contain residual current device (RCD) protection. NOTE – The only current recommended RCD is a type b. See Figure 18 for type b RCD markings."

DZ PAS 2011 at page 12 defines "Residual direct current detecting device (RCD-DD): This is used for charging electric vehicles. RDC-DDs are intended to remove or initiate removal of the supply to electric vehicles, in cases where a smooth residual direct current equal to or above 6 mA is detected (IEC 62955). The value of 6 mA for smooth residual direct current was chosen to
prevent impairing the correct operation of an upstream RCD Type A."

PDL is currently advising (in a trade blog) "So yes, Type B RCDs are a little bit more expensive, but they also provide a more reliable solution for the home owner with less likelihood of tripping [than an RCD-DD, as is currently supplied in some mode-3 EVSEs], and therefore less chance they will wake up in the morning without a fully charged electric vehicle and wondering why."

I'm hoping this little type-b vs rcd-dd puzzle can be sorted out by the standards committee in a way that won't be onerous to suppliers of mode-3 EVSEs (who may well have inventory of ones with RCD-DD) or to consumers (who may purchase mode-3 EVSEs whose false-trips only become evident many months after the installation of the EVSE). Any false-trips will indeed be annoying and possibly very disrupting, but are not a safety hazard... a difficult little puzzle but

My main concern remains: that NZ PAS 2011 should allow the residential use of the IC-CPDs that will be routinely be supplied with our imported EVs, so long as they are fitted with an appropriate AC plug by a registered electrician, so long as they are plugged into an AC socket that has been inspected and is clearly labelled as being safe to use for EV charging, and so long as they are supplied with an SNZ-approved set of operating instructions. That's a pretty tall order... and obviously it'll be a lot easier for the standards committee to issue a document that deprecates all residential use of IC-CPDs, nevermind that (I suspect) IC-CPDs will still probably still be routinely used on sockets which haven't been inspected for earth-fault or current-carrying capacity... which would IMHO be a regulatory failure... but hey we just do what we can, and it's hard-yards to write such advice to consumers!

richms

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#2627033 26-Dec-2020 21:48

Lets hope they never have the idea of regulating how we charge other things because it all seems like so much compliance.

Have any of these problems they come up with happened before?

Why is a car suddenly so much more risk than any other metal earthed appliance?

If they want people to use EVs and charge them, then going on about with expensive breakers and dedicated wiring isnt going to help. Most people will just be plugging in whatever charger to whatever outlet, and letting it go.

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#2627058 27-Dec-2020 00:11

My current *guess* as to WorkSafe's intended meaning of this requirement is that the EV charging must stop if the CP circuit is opened. (There's a resistor between the PE and the neutral in the Type 1 or Type 2 plug on a mode-2 EV charging cable, this is what closes the CP circuit.) This requirement is easily met, and I'd *hope* that all IC-CPDs do indeed stop charging immediately the CP circuit is carrying either too much or too little current.

Are any (or all!) IC-CPDs in NZ continuously testing whether the ground-pin supply never has much of a voltage drop to its neutral-pin supply? This is (very roughly) what an RCD does... and I suspect it's the reason why RCDs are sometimes marketed (e.g. by PDL/Schneider) as "Earth Leakage Circuit Breakers". The WorkSafe requirement to "incorporate an RCD function to provide protection against electric shock" is in addition to the requirement to continuously monitor "earth continuity"... and...

Testing between the PE pin and CP pin confirms that the earth wire between the EVSE and vehicle is intact, as they're bridged by a resistor in the car. It does not prove that the earthing upstream of the EVSE is OK. All it proves is a vehicle is connected.

That has nothing to do with how an RCD operates; it's closer to the now-illegal VO-ELCBs which never really worked well.

IC-CPDs I believe are *supposed* to include RCDs; this is why there is some debate as to the neccesity of providing a DC- sensitive RCD both in the switchboard and in the EVSE.

I don't see an RCD label on any of the (3!) IC-CPDs I own. All do carry a notice warning that it should only be used with a power source that has an RCD breaker. That lack of RCD label, I believe, puts them all out of compliance with WorkSafe -- and once again I'm wondering if they're over-regulating. Yes you have to be careful to use a more-sensitive RCD downstream of the RCD-a on a circuit board... and life would certainly be simpler for everyone if all IC-CPDs had an onboard RCD that was appropriately specified for being downstream of an RCD Type A... but in the world I live in, I'm almost certain that none of my IC-CPDs have such an RCD.

They probably should include residual current protection of some sort. There's no particular issue with any of the RCDs being upstream or downstream; from a technical point of view you just need an RCD that is sensitive to smooth DC residual currents at some point.

Research suggests that an 'RCD-DD' probably opens a contactor rather than directly interrupting the mains, so is more likely to either be bypassable or not operate when required. RCDs generally require manual resetting.

Our regulators appear to have basically decided that EVSE can't be relied on to be compliant so they want everything to have a Type B at the board so that everything is safe regardless of what happens in the EVSE.

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#2627059 27-Dec-2020 00:11

My main concern remains: that NZ PAS 2011 should allow the residential use of the IC-CPDs that will be routinely be supplied with our imported EVs, so long as they are fitted with an appropriate AC plug by a registered electrician, so long as they are plugged into an AC socket that has been inspected and is clearly labelled as being safe to use for EV charging, and so long as they are supplied with an SNZ-approved set of operating instructions. That's a pretty tall order... and obviously it'll be a lot easier for the standards committee to issue a document that deprecates all residential use of IC-CPDs, nevermind that (I suspect) IC-CPDs will still probably still be routinely used on sockets which haven't been inspected for earth-fault or current-carrying capacity... which would IMHO be a regulatory failure... but hey we just do what we can, and it's hard-yards to write such advice to consumers!

If it doesn't come into the country with the correct plug, it's already illegal to bring it into the country.

Testing sockets is a crapshoot that no-one wants to be liable for and would need to be time-limited. There's stuff-all that an electrician will do to test them that can't be done in a sufficiently advanced piece of EVSE.

Lets hope they never have the idea of regulating how we charge other things because it all seems like so much compliance.

Have any of these problems they come up with happened before?

Why is a car suddenly so much more risk than any other metal earthed appliance?

If they want people to use EVs and charge them, then going on about with expensive breakers and dedicated wiring isnt going to help. Most people will just be plugging in whatever charger to whatever outlet, and letting it go.

A couple of people dying while charging EVs would put a damper on the uptake of charging EVs too.

EVs have a bunch of issues that create something of a perfect storm:

They are often in wet areas. Most other equipment in wet areas is either not interacted with much (AC units, outside lights) or required to be double insulated or fed at ELV (power tools, some pool equipment).
They're fed by a flexible cord exposed to damage. What's more, it's an *expensive* cord, so people will be more likely to ignore damage.
Connected via plug-and-socket.
They're full of power electronics that produce a lot of leakage current - other equipment with this issue (VFDs mainly) is usually required to be hardwired, and usually everything is a lot more thoroughly bonded together. You still often have issues with bearing failures from leakage current.
They produce leakage current, again - many types of RCDs not only don't detect high frequency or DC leakage, it actually prevents them from tripping.
High voltage DC onboard the vehicle. Again, VFDs and AC units have this... but are hardwired and full of instructions warning that bonding must be present.
They're very high power. This means that many of the above issues are far more serious.

One other consideration that I haven't seen mentioned is the risk of a broken mains neutral causing earth rise - this gets worse the more earthed equipment is outside the building, and a metal-bodied car in a carport is nearly the textbook example of this, just behind the garden tap.

The charger may disconnect the supply to the car if this occurs (due to voltage out of limits), which would reduce the load on the building and thus the volt drop down the neutral, but the voltage between the building earthing system (including the car chassis, as switching earth is generally forbidden) and true earth would still be excessive and potentially fatal if there were other high-power loads in the property. I'm surprised the decision wasn't made on Day 0 that the charging equipment would be completely isolated, line neutral and earth, from the chassis of the car.

This appears to be behind yet another set of new UK rules, which look decidedly simple and cheap compared to ours.

Post split as apparently I had too many quotes.

cthombor

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#2627077 27-Dec-2020 07:46

Thanks everyone, this is a great discussion so far! I'm learning a lot, and I hope others are too.

I'm hearing

* some disagreement about empirically-measurable facts (e.g. the electrical characteristics of the typical IC-CPD currently in NZ),

* a considerable range in our grasp of electrical and electrical-safety concepts, and

* a wide divergence in our underlying values such as

the importance of individual freedom even for Darwin-awardable activities,
the importance of safety regulations which mitigate the risk of shocks and fires,
the importance of non-monetary societal goals which aren't normally considered when setting electrical standards (such as greenhouse-gas reduction),
the importance of dollar-measurable costs (such as ACC claims, fire-cover claims, and uncovered costs to individuals due to unsafe use of an IC-CPD), versus the additional costs borne by consumers and/or suppliers if some moderate-risk residential uses of IC-CPDs are effectively unregulated, versus the additional costs of regulatory-enforcement (whether by carrot or by stick).

I'd suggest that, as geeks, we try to support each other in identifying and learning about the most relevant concepts, that we identify (but not waffle on and on about our personal opinions about the truth-values of) the important empirically-verifiable facts, and that we identify and disclose our own values (but never argue about the validity of anyone else's disclosures). Our disagreements and divergences, as well as any rough-agreement we gain on the facts and concepts, will IMHO be extremely important for the standards committee to know. My reasoning: if they don't know this, then how could they possibly write a PAS which expresses (in a way that is understandable at least to NZ geeks) what every NZ consumer and user of residential EV-charging equipment really "should" know before they purchase or use this equipment.

Also I'd suggest: if you notice an important fact or concept raised by someone *other* than yourself which seems worthy of additional discussion, please consider opening a new thread with an informative subject line. I think this discussion-thread is already long enough (mostly because of my apparently-uncontrollable logorrhoea ;-) to discourage anyone from reading very much of it.

Anyway that's my suggestion going forward on this thread... and thanks again!

cthombor

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#2627085 27-Dec-2020 08:38

My websearch just now revealed some NZ suppliers of residentially-sized GFCIs (e.g. 30 A / 230 VAC), and some electricians who are recommending their residential use. These puppies are called GFIs in the USA. They're required in most (if not all) US states, at least for outlets in wet areas, with provision for inline relays (e.g. MOLEX 13053 series) as well as circuit breakers.

From tech-blogs in the USA I have come to the (tentative!) conclusion that GFCIs are somewhat prone to false-tripping -- especially if there's more than one on a circuit. This has made for rather a messy regulatory puzzle in the USA, as its state-level regulatory agencies are still trying to sort out how to harmonise their existing GFCI regulations with the new kids on their block: the mode-3 tethered EVSE (with an internal GFCI), a mode-3 untethered EVSE (which might conceivably have a GFCI in its connection to the EV), and in a SAE J1772-compliant IC-CPD (with what I vaguely understand to be its built-in GFCI functionality).

As far as I can tell, there's not much motion in the EU towards sorting out how to revise IEC 61851 so that it'll require a form of ground/earth-fault protection that's appropriate for (each of the many!) different earthing systems that are in play. Given that some systems don't provide an earth-ground at their power points, I can't see how this regulatory-puzzle could possibly be resolved without a requirement that the IC-CPD must be plugged into a 61851-compliant source of AC power -- with a separate earth ground being required for wiring this outlet, at least in some areas??? Gadzooks that's not likely to happen anytime soon. There's a similar problem in the UK.

Seems to me that it'd be reasonable to hope that, eventually, SNZ and WorkSafe will agree that IC-CPDs can (with only a moderate safety risk) be plugged into a socket that has been certified "safe" for EV charging. The socket should have a GFCI that'll not false-trip when a Type-1 IC-CPD is used, but which will still provide safety when a Type-2 IC-CPD is used -- but specifying such a GFCI (if this is even feasible) is far beyond my level of competence! The label should IMHO display the amperage limit (e.g. 8 A for a 10 A plug), and an expiry date, and perhaps a warning against daily plugging and unplugging of the IC-CPD -- with the expiry-date reflecting the safe life-expectancy of an AC outlet that is used, say, every other day -- with weekly hot-connect or hot-disconnect abuses? (Kiwis are pretty well accustomed to avoid hot-connects and hot-disconnects on their AC sockets but I'm confident PDL's safety-engineers could offer an expert opinion on how long their competitor's sockets are likely to last ... and *maybe* this discussion would result in an appropriate tightening of the specs on a socket that can be labelled "safe"... and maybe the label should say "inspected" rather than "safe", to make it clear that nobody can warranty the safety of anyone whose behaviour is worthy of a Darwin award...) Anyway it seems a possibility... what do you think?

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#2627091 27-Dec-2020 08:50

This discussion is beyond my area of expertise. I'd like to see a bit of a summary so we can decide if it's something we need to be concerned about.

I recently had a 32A socket installed with the intent of making what would normally be a fixed charger portable, by adding a suitable plug instead of hard wiring it. Obviously, this new circuit is RCD protected, but it's not dedicated to vehicle charging.

Does anything about this proposed standard limit my ability to do what I have been or intend to be doing?

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#2627092 27-Dec-2020 08:52

how many A is a normal house mains electrical supply rated to? sorry dumb Q

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#2627132 27-Dec-2020 11:15

cthombor:

My websearch just now revealed some NZ suppliers of residentially-sized GFCIs (e.g. 30 A / 230 VAC), and some electricians who are recommending their residential use. These puppies are called GFIs in the USA. They're required in most (if not all) US states, at least for outlets in wet areas, with provision for inline relays (e.g. MOLEX 13053 series) as well as circuit breakers.

From tech-blogs in the USA I have come to the (tentative!) conclusion that GFCIs are somewhat prone to false-tripping -- especially if there's more than one on a circuit. This has made for rather a messy regulatory puzzle in the USA, as its state-level regulatory agencies are still trying to sort out how to harmonise their existing GFCI regulations with the new kids on their block: the mode-3 tethered EVSE (with an internal GFCI), a mode-3 untethered EVSE (which might conceivably have a GFCI in its connection to the EV), and in a SAE J1772-compliant IC-CPD (with what I vaguely understand to be its built-in GFCI functionality).

I can't find anything re 13053. Relays are generally not acceptable for life safety (insufficient reliability and isolation ratings) and also fail the requirements for safety devices to be fundamentally incapable of automatically resetting.

The US 'GFCI' is typically about 6x more sensitive than the European equivalent we use, although there are some different sensitivities available.

Neither GFCIs nor RCDs are capable of tripping each other nor does using multiple in any way increase the chance of any one false tripping - this is a frequent, fundamental misunderstanding. In some cases the test function can trip other RCDs/GFCIs (but this is unusual), and they do not discriminate so either or both may trip in a fault, but there is fundamentally nothing wrong with using them in series and in some cases (construction sites) this is effectively mandatory.

As far as I can tell, there's not much motion in the EU towards sorting out how to revise IEC 61851 so that it'll require a form of ground/earth-fault protection that's appropriate for (each of the many!) different earthing systems that are in play. Given that some systems don't provide an earth-ground at their power points, I can't see how this regulatory-puzzle could possibly be resolved without a requirement that the IC-CPD must be plugged into a 61851-compliant source of AC power -- with a separate earth ground being required for wiring this outlet, at least in some areas??? Gadzooks that's not likely to happen anytime soon. There's a similar problem in the UK.

Seems to me that it'd be reasonable to hope that, eventually, SNZ and WorkSafe will agree that IC-CPDs can (with only a moderate safety risk) be plugged into a socket that has been certified "safe" for EV charging. The socket should have a GFCI that'll not false-trip when a Type-1 IC-CPD is used, but which will still provide safety when a Type-2 IC-CPD is used -- but specifying such a GFCI (if this is even feasible) is far beyond my level of competence! The label should IMHO display the amperage limit (e.g. 8 A for a 10 A plug), and an expiry date, and perhaps a warning against daily plugging and unplugging of the IC-CPD -- with the expiry-date reflecting the safe life-expectancy of an AC outlet that is used, say, every other day -- with weekly hot-connect or hot-disconnect abuses? (Kiwis are pretty well accustomed to avoid hot-connects and hot-disconnects on their AC sockets but I'm confident PDL's safety-engineers could offer an expert opinion on how long their competitor's sockets are likely to last ... and *maybe* this discussion would result in an appropriate tightening of the specs on a socket that can be labelled "safe"... and maybe the label should say "inspected" rather than "safe", to make it clear that nobody can warranty the safety of anyone whose behaviour is worthy of a Darwin award...) Anyway it seems a possibility... what do you think?

Sockets without a ground are fundamentally unsuitable for use with EVs. The chargers produce significant leakage current which, while probably not fatal, could easily cause pain and possibly involuntary muscle contraction if it passes through a person rather than ground.

GFCIs are not NZ compliant and never will be. A type B RCD is not going to cause false tripping issues and will pick up on any relevant faults; that is why they are suggested/required under the current guidelines.

3112 sockets are not especially robust long term and if you want to require old ones to be replaced for car charging... put in a proper EVSE in the first place.

Honestly I am surprised that EVSE and IC-CPDs are only DMRAs not DHRAs. Some of the stuff available for sale here probably should not be.

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