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Posted By Topic: EV Chargers

north1
Sep 06 2019 17:27

I have been asked to install x2 separate power points to be used with x2 EV chargers.
The EV chargers are rated at 10 amp each.
The client wants to fit the power points for the EV chargers in a external garage from the house.
The garage switch board is a old type plastic cover with x3 fuses fitted into it behind cover.
The MEN link in the garage switch board has been removed and the supply from house is on a 25 amp RCD/MCB
The supply cable to the garage is 6 mm T&E.
I would like to fit x2 MCBs in a enclosed MCB housing along side the existing switch board.
The x2 MCBs would supply each power point for the x2 EV chargers.
Supply to be taken from the garage existing sw/bd to enclosed new MCB housing.
Any problems with this idea.

Thanks
North 1
   

gregmcc
Sep 07 2019 05:08

I would recommend have a read of the EV charger guidelines from Worksafe, keep in mind these are guidelines not a cited standard or legislation, but it is likely that in the future a standard will be based on these.

https://worksafe.govt.nz/dmsdocument/5169-electric-vehicle-charging-safety-guidelines-2nd-edition
   

AlecK
Sep 07 2019 11:49

That would be 2 x sockets intended for Mode 2 charging.
While the particular charging equipment your client wants to use may only draw 10 A, the "requirements for Mode 2 in AS/NZS 3000:2018 +A1 require each of these sockets to be supplied by a subcircuit that doesn't supply anything else (commonly called a dedicated subcircuit); and each of them must have a CCC of 20 A.

Which effectively means adding 40 A to the Max Demand for both the submains and the mains, - and you just haven't got that much headroom without at least a submains upgrade and possibly a mains upgrade.

Another issue is RCD protection, which should be Type B for each circuit.

   

north1
Sep 07 2019 12:19

Hi Alex

Thanks for your reply.

You refer to Mode 2 charging for the application I have listed in my query.
Info taken below from Worksafe info.
They comment that mode 2 is for public use.
What mode ?? would I use for the application I have been asked by my client for his requirements.
Am I correct in thinking that x2 separate supplies ( 6 mm T&E )would have to be taken from the house main switch board to each of the charging plugs in the outside garage.
House supply mains are 3 phase 16 mm.
Am I correct in thinking that re your reply that it is not possible to supply the EV plugs from the existing garage supply switch board.

Thank You
North 1


Mode 1 charging

In New Zealand:
a. It is not permitted to install a socket-outlet with the intention to provide
Mode 1 charging for an electric vehicle.
b. It is not permitted to install, use or allow the use of Mode 1 charging in
locations that are not domestic or similar.
c. Mode 1 charging of an electric vehicle at a domestic or similar installation
may only be undertaken where the supply is protected by a Type A RCD.

Mode 2 charging
In New Zealand, it is not permitted to use or allow the use of a Mode 2 supply
for public charging for an electric vehicle.
The maximum current for Mode 2 charging is 32 A.
Each socket-outlet should have an earthing contact connected to the protective
earth conductor2 (PE).

Mode 3 charging
In New Zealand, it is permitted to install and use Mode 3 EVSE.

Mode 4 charging
In New Zealand, it is permitted to install and use Mode 4 EVSE.

   

evanh
Sep 07 2019 12:40

North1,
You've misread the Mode 2 rule. It says "not permitted" for public charging.

   

AlecK
Sep 07 2019 13:09

first work out what mode the intended charging equipment is. The Modes are defined in both the Worksafe guidelines and in App P of AS/NZS 3000. Unfortunately those definitions are not compatible WRT Modes 1 & 2. the first edition of the guidelines defined Mode 1 as limited to 8A. The current edition doesn't use rating, of either socket or equipment, as a factor; but instead defines Mode 1 as not having any supplementary pilot or auxiliary contacts, whereas Mode 2 has these. These later definitions are reasonably well aligned with clauses P1.5.2 & P 1.5.3 of 3000:2018.
My initial assumption of Mode 2 was based on memory of the 8A limit in the older definition; but under the newer definition, and under AppP, I'll revise that and say it's Mode 1 EVSE.

Regardless of which definition we use, plug-in EVSE can only be Mode 1 or Mode 2.

Neither the guidelines nor the Standard have any legally binding force. The Standard will be cited by ESRs, but likely to be sometime next year before that happens.

So you don't have to comply with either, but you should try to comply with both.

If you conclude that the EVSE your customer has is Mode 1, then simply install a couple of socket outlets for general purpose use.
To be clear, it is not permitted to install sockets for Mode 1 in NZ, but it is permitted to use Mode 1 EVSE in NZ by plugging it into a general purpose socket outlet. Which is what I'd be doing in your place.

If it is Mode 2 equipment, then you should be installing 2 dedicated circuits , each with CCC of 20 A, and each protected by Type B RCD or alternatively Type A RDC in conjunction with a special residual d.c. detecting device (RDCDD).

There is no PEN conductor in the circuit; nor in the submains to the outbuilding; so as long as the existing submains and mains can handle the extra load there's no problem with adding these supplies in the garage.

AppC, Table C1, load group J states that the sockets / equipment for charging EVs is assessed at 100% of connected load - connected load effectively being the rating of the socket for socket-connected equipment.

This will mean that sometimes when EVSE is installed, the mains will require upgrading. Meaning that EVERY time, we have to look at what the MD of the installation is now, and consider whether we can add that without adversely affecting safety (eg voltage drop).