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Posted By Topic: EV charger

earichard
Sep 04 2019 20:21

Hi there I am swapping out a 22kw 3 phase charger for two 7kw single phase chargers. One will replace the existing one which is fed from the main switchboard and the other will be on another building fed from a distribution board with its own earth stake. I have read some of the other threads and the worksafe guidelines around the requirement for type b rcds. But the manufacturers website specifically states no need for type b rcd as residual dc protection is incorporated into the charging unit. Thoughts on this?

https://evnex.com/products/r-series-intelligent-charging-station
https://evnex.com/products/r-series-intelligent-charging-station
   

pluto
Sep 04 2019 20:28

The Worksafe Guidelines requires that ALL EV chargers must be connrected to the main switchboard of the electrical installation in which they are installed.
   

earichard
Sep 04 2019 20:49

Sorry I have reread that and can’t find anything about that requirement do you have a page number/reference?
   

Sarmajor
Sep 05 2019 07:18

The guidelines recommend that EV chargers be supplied from a TNC system with an MEN link and an Earthing Electrode. Section 1.4F of the guidelines.

An outbuilding supplied with a PEN mains and fitted with a main earthing system fits the bill perfectly.

Earichard, you can stop looking for any requirement for EV to be connected to the Main Switchboard of an Installation because it simply is not there.
   

DougP
Sep 05 2019 07:46

But it did make it into 3000:2018 7.9.2 Sarmajor
   

pluto
Sep 05 2019 08:57

Sarmajor Sep 05 2019 07:18

Your comment 1

The guidelines recommend that EV chargers be supplied from a TNC system with an MEN link and an Earthing Electrode. Section 1.4F of the guidelines.

My comment 1
Using the EV charging guidelines V2 published in April 2019 it is in 2 sections 1.5 (f) and 2.3 and requires a TNC-S supply. The -S at the end means that the earthing conductors in the electrical installation are kept separate in ALL parts of the electrical installation.

Your comment 2
An outbuilding supplied with a PEN mains and fitted with a main earthing system fits the bill perfectly.

My comment 2
The above statement is NOT correct. This is because the submain supplying the outbuilding switchboard the neutral and earth are a common cable core and hence does NOT comply with the TNC-S system of supply in the whole of the electrical installation.

Your comment 3
Earichard, you can stop looking for any requirement for EV to be connected to the Main Switchboard of an Installation because it simply is not there.

My comment 3
This is NOT correct. See my above comments.

The use of the IEC sxpressions; TN-C, TNC-S, IT and TT systems of supply all indicate the supply configurations. To many to the new exprsssions will need to be clearly understood by all when other systems of supply are introduced into NZ near future.

The current so called MEN system of supply as used in AU and NZ is NOT true equal of TNC-S.

The earthing of EV charging systems is critical to get right because of the earthing monitoring systems used in EVs and when a PEN conductor is used upstream of EV charger the earth monitoring system will often detect this connection and turn off the supply to the EV.
   

DougP
Sep 05 2019 09:18

I don't think the "EV charger will detect this" upstream. I don't see how it could detect anything past the outbuilding MEN link.

The EV charger will _not_ be able to detect any problem in the PEN earthing - that's the main problem isn't it?
   

pluto
Sep 05 2019 09:53

Yes.


   

AlecK
Sep 06 2019 10:49

TNC-S does NOT require that all of the installation has separate N & E conductors.
It simply denotes a system whereby both common ("C") and separate ("S") N & E conductors are used.

Our "MEN distribution system is one particular variant of TNC-S.

If an EV charger can somehow detect / be adversely influenced by having a PEN conductor upstream of it, then we're in real trouble because (almost) EVERY installation has a PEN conductor in the mains.


   

Sarmajor
Sep 06 2019 19:42

And that was my logic for constructing my answer.

There is no difference between the supply authorities PEN and a PEN from the main switchboard out to an outbuilding. Same system just NOT called the main switchboard..

Once again it DOES NOT say that the EV charger has to be connected to the MAIN SWITCHBOARD.
What it does say in 1.4f is this

f. be supplied from a TNC-S (MEN) system of supply that includes an earth electrode and MEN connection,

   

earichard
Sep 06 2019 20:21

I rang the supplier who was more confused about the definition of what a dedicated sub circuit was which is quite worrying but he gave me a contact at worksafe who I spoke to and he was fine with running it from the sub board because it’s an MEN board. He told me to get the supplier to provide a sdoc specifically mentioning the rcd-dd and attach it to the coc and that would then only require a type a rcd instead of a type b.

It’s pretty black and white in the 2018 wiring rules that it can only be supplied from the main switchboard but obviously they haven’t been cited yet.
He said the reason they are recommending running it from the main switchboard is that in the future when a car is charging and the load being drawn from cooking heating etc gets too high the charger will start drawing current back from the battery and into the house, although this technology has not yet been developed.
   

pluto
Sep 06 2019 20:47

For information, an IEC standard IEC 60909 for charging an EV battery and/or discharging a EV battey to produce an LV supply using a both way grid-connect inverter does exist and I understand is being made by some inverter vendors.
   

AlecK
Sep 07 2019 11:35

What the "requirement" to supply from a TNC-S installation doers is prohibit utilities from installing roadside charging booths directly on the network (which is TNC, not TNC-S); and that's why the rule exists.
It also prohibits supply from other earthing systems eg TT or IT.

I put those inverted commas around "requirements" because while both EVCSGs and 3000:2018 use words like "shall"; they are still not requirements because they have not bee mandated by citation (eg in ESRs). Therefore NONE of the provisions is currently mandatory, it's all just guidance.

Not only has 3000:2018 not been cited yet; but a revised clause is coming in the Amendment currently under way. Which will almost certainly be published long before ESRs get around to citing the new edition of the Standard.

latest info is that an actual regs amendment is not on the cards at present, all we'll get - this year or next - is an update of Schedules 2 & 4. In which case the "rules" will be 3000:2018 + A1; and the EVCSGs will remain guidance-only until government allows an amendment to the main body of ESRs.