Wiring a new home for an electric vehicle.

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mattwnz

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#257110 15-Sep-2019 23:06

Hi guys. after my water tank question, I have another electrical question, and this time about the wiring for an electrical vehicle. It was specified on the plans for a new home, for a 32A circuit to be installed in the garage, to be used in the future for electrical vehicle charging, to future proof it. At the moment it just has a normal power socket on it, but eventually it will be hooked up to a EV charging station that plugs directly into an electric car.

Now the electrician has named some of the circuits in the distribution board, we noticed that the EV socket is using a C16 circuit breaker as per the photo below, which appears to be rated at 16 A. S I understand 32 A allows a car to be charged in double the time. Would the fact that he has used a 16A circuit breaker indicate that it is likely that he hasn't wired it up with 32A capable cable? If so what would be the process of getting it correct...rewiring it?

The other concern is that there doesn't appear to be a dedicated RCD on this circuit. According to the note in the distribution board, the RCD 7 to the left is for all the power circuits on the right of the RCD. SO the circuit breakers to the left RCD7 don't appear to be on any RCD at all. However I was reading that an EV circuit must now be on a dedicated RCD in order to be compliant. Is this correct, does this EV need it's own dedicated RCD and must that have been installed?

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#2318316 15-Sep-2019 23:43

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The special RCD required is "Type B" they are expensive and massive.

https://oemaudio.co.nz/product/rcd-type-b-suitable-for-electric-vehicle-charging-nz-worksafe-approved/

With regards to the wire itself, somebody would need to know the size (cross sectional area), and approx run length, to determine if it can carry 32A.

Seeing the other issue I would probable assume the worst for this one.

mattwnz

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#2318320 16-Sep-2019 00:22

Scott3:

The special RCD required is "Type B" they are expensive and massive.

https://oemaudio.co.nz/product/rcd-type-b-suitable-for-electric-vehicle-charging-nz-worksafe-approved/

With regards to the wire itself, somebody would need to know the size (cross sectional area), and approx run length, to determine if it can carry 32A.

Seeing the other issue I would probable assume the worst for this one.

Thanks for that. We will get an electrician to come and check the wiring onsite to make sure it is to the specified capacity, I hope it is but the circuit breaker doesn't look promising. Yes the RCDs do take up quite a bit of space on the distribution board, looks like that one takes the space of 4 normal circuit breakers. If it is a requirement under the new AS/NZS3000, should they still be required to have installed it in order to be compliant? They were supposed to leave 20% space capacity on the distribution board for things to be added, which installing this will probably take it down to 10 percent. The whole point in specifying it on the plans, was to make sure the garage is future proof, and they were aware it was an EV.

Zeon

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#2318321 16-Sep-2019 00:37

Take the face place off the garage socket and check the wire behind. It should be thicker - it may even have the type and cross sectional size printed on it. I think you need at least 10mm cross section copper cable for 32A "officially" but it really depends on how much voltage-drop/loss/regulations/insurance-exclusions you want to work with. Here is a useful page:

https://www.jcalc.net/cable-sizing-calculator-as3008

I'm not sure if the table on there is correct though as it's saying 16mm is rated to 40A but we have it it on 63A breakers from the street. Just a note those cables can cost a tonne.

Note I am not an electrician or electrical engineer - I've been doing my own research on this stuff for my DC home project and also re-wiring AC throughput the property and working with the elctricial on that too. It may be worth getting a couple of different electricians for an opinion potentially?

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mattwnz

15416 posts

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#2318322 16-Sep-2019 00:44

Zeon:

Take the face place off the garage socket and check the wire behind. It should be thicker - it may even have the type and cross sectional size printed on it. I think you need at least 10mm cross section copper cable for 32A "officially" but it really depends on how much voltage-drop/loss/regulations/insurance-exclusions you want to work with. Here is a useful page:

https://www.jcalc.net/cable-sizing-calculator-as3008

I'm not sure if the table on there is correct though as it's saying 16mm is rated to 40A but we have it it on 63A breakers from the street. Just a note those cables can cost a tonne.

Note I am not an electrician or electrical engineer - I've been doing my own research on this stuff for my DC home project and also re-wiring AC throughput the property and working with the elctricial on that too. It may be worth getting a couple of different electricians for an opinion potentially?

Thanks I might try that. I think the 32A ones are the same they use for ovens, so they are quite a bit thicker, but still relatively standard type of cable for a new home. So I think in terms of the cabling, it was just a case of them using one of those type of cables.

gregmcc

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#2318323 16-Sep-2019 05:20

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mattwnz:

Hi guys. after my water tank question, I have another electrical question, and this time about the wiring for an electrical vehicle. It was specified on the plans for a new home, for a 32A circuit to be installed in the garage, to be used in the future for electrical vehicle charging, to future proof it. At the moment it just has a normal power socket on it, but eventually it will be hooked up to a EV charging station that plugs directly into an electric car.

Now the electrician has named some of the circuits in the distribution board, we noticed that the EV socket is using a C16 circuit breaker as per the photo below, which appears to be rated at 16 A. S I understand 32 A allows a car to be charged in double the time. Would the fact that he has used a 16A circuit breaker indicate that it is likely that he hasn't wired it up with 32A capable cable? If so what would be the process of getting it correct...rewiring it?

The other concern is that there doesn't appear to be a dedicated RCD on this circuit. According to the note in the distribution board, the RCD 7 to the left is for all the power circuits on the right of the RCD. SO the circuit breakers to the left RCD7 don't appear to be on any RCD at all. However I was reading that an EV circuit must now be on a dedicated RCD in order to be compliant. Is this correct, does this EV need it's own dedicated RCD and must that have been installed?

Keep in mind that all the rules for EV chargers are "Guidelines" only, they are not a standard, they are not cited by the law.

even if the circuit breaker for the socket for this future EV charger is connected up it still must be protected by an RCD, if it's not then it's non compliant.

Do you have at least 2 RCD's on your distribution board?

Are there more than 3 circuits off each RCD?

Its beginning to look like your wiring has been done by a cowboy, maybe it's time to engage an electrical inspector to do a full compliance check?

Tracer

278 posts

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#2318821 16-Sep-2019 21:39

I second @gregmcc's assessment. If there's a socket outlet on that circuit without an RCD it is not compliant.

nickb800

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#2318865 17-Sep-2019 06:33

Putting aside the lack of an RCD, if the sparky did run 6mm2 cable, he might have put a lower rated MCB to match the better match the capacity of the socket - expecting you to upgrade the MCB when you upgrade the socket in future? My understanding is that MCB ratings are primarily about protecting the cable rather than sockets or things plugged in, but a 32A MCB on a single 10A socket would 'seem' weird at the very least.

mattwnz

15416 posts

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#2319390 17-Sep-2019 19:31

Tracer:

I second @gregmcc's assessment. If there's a socket outlet on that circuit without an RCD it is not compliant.

At the moment there is just a normal powerpoint at the end of the circuit. We told the electrician just to install a normal power point at this stage as we are not ready to install a charging station, plus we won't know what sort of socket type of the charging station we want until we buy an EV which could be years down the track. But once we do, we would expect that the sparky would just come in and remove the power point, and then install the charging station over the top, and no further work to the distribution board would be needed. At the moment it looks like circuit breakers in the distribution board would need to be moved to fit the RCD in which is potentially quite of lot of additional work.

Zeon

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#2319464 17-Sep-2019 20:37

mattwnz:

Tracer:

I second @gregmcc's assessment. If there's a socket outlet on that circuit without an RCD it is not compliant.

At the moment there is just a normal powerpoint at the end of the circuit. We told the electrician just to install a normal power point at this stage as we are not ready to install a charging station, plus we won't know what sort of socket type of the charging station we want until we buy an EV which could be years down the track. But once we do, we would expect that the sparky would just come in and remove the power point, and then install the charging station over the top, and no further work to the distribution board would be needed. At the moment it looks like circuit breakers in the distribution board would need to be moved to fit the RCD in which is potentially quite of lot of additional work.

I don't think they could put a higher capacity circuit breaker on if you have a normal power point though as it would exceed the rating of that power point. RCD is another story.

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raytaylor

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#2319466 17-Sep-2019 20:38

So if there is a normal 10 amp socket, he cant put a 32amp fuse on it because the socket could cause a fault and the fuse could not act as a protection device.

When you replace the socket, you would then have to upgrade the fuse to match it and possibly as mentioned, the RCD at the same time. Its still quite possible that the correct cabling has been installed within the wall - it will be pretty easy to tell just by comparing the cable thickness behind two wall sockets.

Another possibility is that the cable could be upgraded later if there is crawl space in the attic and the holes are wide enough to fit the new cable so it can be easily pulled through.

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Batman

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#2319469 17-Sep-2019 20:46

how many amps does the house mains need to be to accommodate this?

i was looking at a house and it had a 62amp single phase power main ... is that an issue?

Involuntary autocorrect in operation on mobile device. Apologies in advance.

mattwnz

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#2319497 17-Sep-2019 21:31

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raytaylor:

So if there is a normal 10 amp socket, he cant put a 32amp fuse on it because the socket could cause a fault and the fuse could not act as a protection device.

When you replace the socket, you would then have to upgrade the fuse to match it and possibly as mentioned, the RCD at the same time. Its still quite possible that the correct cabling has been installed within the wall - it will be pretty easy to tell just by comparing the cable thickness behind two wall sockets.

Another possibility is that the cable could be upgraded later if there is crawl space in the attic and the holes are wide enough to fit the new cable so it can be easily pulled through.

Thanks, yes that makes sense. I had forgotten that you don't want a regular socket ever being at risk of drawing that amount of power though it. I think it is likely therefore that the right cable has been used. We may instead therefore just get them to put in a blanking plate instead of a socket and not use it, so it can be setup easier for an EV in the future.

Scott3

691 posts

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#2319510 17-Sep-2019 22:11

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raytaylor:

So if there is a normal 10 amp socket, he cant put a 32amp fuse on it because the socket could cause a fault and the fuse could not act as a protection device.

When you replace the socket, you would then have to upgrade the fuse to match it and possibly as mentioned, the RCD at the same time. Its still quite possible that the correct cabling has been installed within the wall - it will be pretty easy to tell just by comparing the cable thickness behind two wall sockets.

Another possibility is that the cable could be upgraded later if there is crawl space in the attic and the holes are wide enough to fit the new cable so it can be easily pulled through.

Fuses on circuit boards are quite rare these days.

My understanding is that the circuit breaker at the switchboard only serves to protect the wire from overload, not individual sockets. This is why it is common to have 10A sockets on circuits protected by 16A and 20A breakers. I haven't found anything to say a 32A breaker would be not allowed on a circuit with 10A socket outlets.

gregmcc

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#2319540 18-Sep-2019 04:43

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Batman:

how many amps does the house mains need to be to accommodate this?

i was looking at a house and it had a 62amp single phase power main ... is that an issue?

This is the typical household supply, And this is the problem with EV charging. a normal EV charger is 32 amps. it's like having another electric stove running overnight.

The power grid in NZ simply does not have enough capacity in the infrastructure for a mass move to EV charging, let alone the power generation capacity.....

Batman

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#2319546 18-Sep-2019 06:22

gregmcc:

Batman:

how many amps does the house mains need to be to accommodate this?

i was looking at a house and it had a 62amp single phase power main ... is that an issue?

This is the typical household supply, And this is the problem with EV charging. a normal EV charger is 32 amps. it's like having another electric stove running overnight.

The power grid in NZ simply does not have enough capacity in the infrastructure for a mass move to EV charging, let alone the power generation capacity.....

so it's ok to install the 32A charger in a 62A house main but not to be used during peak times?

forgot to mention the 62A single phase supply has a fuse ... where is the fuse and if you trip the fuse is it difficult to restore it?

Involuntary autocorrect in operation on mobile device. Apologies in advance.

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