New Build: Advice for Power and Data Cabling

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#3368684 29-Apr-2025 12:50

Twincamr2:

Scott3:

I had wrongly assumed it was a new development. Still might be worth looking into the cost to change to a 100A connection if you don't want three phase.

Looked up the max current draw on a 90cm induction cooktop (CI905DTB) and it's 43A, and for a 90cm (OB90S9MEPX3), and it it's 20.63A. I think you might be better suited to a 100A (or three phase feed). I'm sure your sparky will advise.

I have never used downdraft extraction, but to me it seems you are fighting physics... Make sure there is a duct route before you go to far down this path.
For a single phase new build I don't see why you wouldn't put in 32A wiring for both. The cost of the fatter wire vs 16A will be trivial. Basically every wall mounted EVSE supports 32A regardless (and if you are going for a portable EVSE and caravan plug on this side, you can still wire it to the fatter wire to make for an easy upgrade if you ever want a wall mounted EVSE in the future

Need for a Type B RCD is driven by the charger type. Tesla & EVnex do not require: https://www.evnex.com/nz/blogs/ev-charging-and-type-b-rcds

EVnex chargers are are local, and have a heap more smarts than Tesla, including overload protection which the tesla charger lacks. Are a lot more expensive though. Could be quite useful if you are running a 63A feed, but note the need to run a twisted pair back to the circuit board from the server charger to get data from a CT clamp before the walls are closed in. Also note the cheapist of their range can't be the server for a multi charger setup.

Won't work for your layout, but as a note to other's dual EV chargers do exist: https://smartevchargers.co.nz/shop/wall-mount-ev-chargers/dual-output-ev-charger/

Get the point on EV charge speed being usage driven, not battery size driven (we did fine for 2 years with a leaf charged with an 8A charger out a window), but in my mind faster is better regardless if it is reasonably attainable:

Can fit a greater amount of charging into an off peak or free power window if you are on such a power plan.
EV's tend to be more efficient charging faster (overhead loads to enable charging are not turned on for as long).
Reduction of hours the coolant pump is running
Ability to top up faster i.e. if you run say 80km of errands in the morning, then return home for lunch, and to pack the car before heading off on a 400km trip in the afternoon. a 11kW charger will replace that 80km in a ~2 hours, where a 3.6 kW charger will add less than half of that in the same time.
Ability to do back to back long trips.
Of course you might never to the last two things (or do them so rarely that it is not a issue to swing by a fast charger).

Sorry - I should have mentioned that it's a tear down and rebuild project.

16 vs 32A: Fair, as long as there's not a huge marginal cost. I just can't see the use case - We almost never charge both EV's at the same time now, but even if we did, having one of the going a bit (relatively) slower doesn't seem like a big deal. My thinking was not so much the cable, but the cost of the bigger RCD/RCBO.

EVnex vs Tesla - I refuse to give any more money to Elon Musk. Ever. I'm ashamed I ever did. Happy to pay more to support local innovation. I need to do more reading about the EVnex system and how it integrates with solar.

Charging - points taken, especially about the coolant pump and charging window. Our family situation means that long trips are a rarity, and I commute by bike most days. But we can't know what the future holds...

single phase RCBO's cost the same regardless of capacity (based on the below link at least...)

https://eurotechnz.co.nz/products/rcbo-schneider-resi9-slim?variant=45841093689592

So the extra cost driver is the fatter cable.

Good on you for supporting local. EVnex are really pushing forwards when it comes to smarts.

I brought a 2nd hand EO Mini Pro 2. In theory a great solution, but not in practice. The smarts are dependent on the charger connecting to EO's servers, Initially they had a 3+ month restructure, where I had no access to support to resolve, then a they were quite helpfull for a couple of months but never were able to resolve the issue. Then they had advised me that my EVSE had dropped out of the support period and the smarts were no longer offered, so I now have effectively a dumb charger.... Avoid EO...

tweake

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#3368754 29-Apr-2025 14:06

Twincamr2:

Downdrafts are amazing! We've used one for a decade. And they can be vented in any number of ways - no different to a range hood. Could be recirc or a motorized damper with makeup air. Haven't decided yet. There's no really good commercial solution for the latter, but that's a challenge! And it has little to nothing to do with any perceived shortcomings in the Kiwi character. ;)

It's not an ERV, it's an HRV.

have you tested the downdraft unit? not tying to be picky but i'm well used to people saying things work when it doesn't. ie the vapor around the edges goes in therefore it works, but the middle goes straight up. even overhead models often fail to work properly. if you have one at the moment i would love some pics of it being tested. btw i talk to the guys who actually test these things but they can't always publish their clients data.

HRV ??? thats like buying a v6 Ferrari. there is also dozens of cheaper brands. there is even cheap brands like panasonic who are erv only, they don't bother making hrv's.

i mention matt risinger because he has a Zehnder in his own home and has had problems with filters blocking up and you can only use Zehnder filters. erv/hrv filters are only meant to protect the core, not filter the air flow. even he had to go add a proper filter box and one that uses off the shelf filters. manufactures started making finer filters for their erv/hrv as a work around but they flow less and clog up fast.

motorized damper for makeup air just won't work for a dryer. its passable on smaller range hoods especially with aucklands loose passive house air tightness specs. but with downdraft where they oversize the fan to try to make up for the issues, like the dryer you really need a fan for the make up air and of course have vents in suitable location. the fan makes it easier as you can keep the duct size down to something manageable.

its really starting to sound like you been sold a dream and i hope that it won't end up yet another high performance build that comes up for sale a few years later.

acsylaa

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#3368864 29-Apr-2025 17:42

Scott3:

Another little thing, my general power circuits have 16A breakers. Many modern homes have 20A breaker. Suggest going for the latter, for reduced risk of tripping again.

There is more than likely a reason for that, one of them being that your power points are fed by a 1.5mm cable, or that the cable has been de rated for a reason if its a 2.5mm to a 16A MCB.

You cant just install a 20A breaker on any power circuit to solve nusance tripping as you could over rate the cable and burn the cable out, the fusing factor would have changed so wont trip with in the required time for the cable rating, the list goes on.

Twincamr2

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#3368936 29-Apr-2025 19:52

Scott3:

single phase RCBO's cost the same regardless of capacity (based on the below link at least...)

https://eurotechnz.co.nz/products/rcbo-schneider-resi9-slim?variant=45841093689592

So the extra cost driver is the fatter cable.

Good on you for supporting local. EVnex are really pushing forwards when it comes to smarts.

I brought a 2nd hand EO Mini Pro 2. In theory a great solution, but not in practice. The smarts are dependent on the charger connecting to EO's servers, Initially they had a 3+ month restructure, where I had no access to support to resolve, then a they were quite helpfull for a couple of months but never were able to resolve the issue. Then they had advised me that my EVSE had dropped out of the support period and the smarts were no longer offered, so I now have effectively a dumb charger.... Avoid EO...

Great - no real downside! I guess you can install a standard 15 or 16A socket on that circuit.

I saw that there was a recent sale of EO gear and wondered if I should pick some up.

Speaking of current, how would I know what rating is for the mains coming into the house? The main breaker in the distribution box is 100A...

Twincamr2

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#3368937 29-Apr-2025 20:00

acsylaa:

Scott3:

Another little thing, my general power circuits have 16A breakers. Many modern homes have 20A breaker. Suggest going for the latter, for reduced risk of tripping again.

There is more than likely a reason for that, one of them being that your power points are fed by a 1.5mm cable, or that the cable has been de rated for a reason if its a 2.5mm to a 16A MCB.

You cant just install a 20A breaker on any power circuit to solve nusance tripping as you could over rate the cable and burn the cable out, the fusing factor would have changed so wont trip with in the required time for the cable rating, the list goes on.

Yeah, interesting. We had our distribution box replaced about 8 years ago. All circuits have 16A breakers and we've never had any nuisance tripping since. Totally agree that breakers must be sized relative to the cable. Sparky won't allow the wrong breaker anyway I'd guess.

Kickinbac

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#3369015 29-Apr-2025 22:22

Twincamr2:

Scott3:

Give some thought to the dryer in the laundry. if you are going for a vented dryer you will need to provision a duct. That said Heat pump dryers are becoming more common (but are heavier so can't be wall mounted),

I am a big supporter of draw wires and conduits. We had a new house built in my childhood that was future-proofed for computers with a bunch of extra phone sockets. Complete waste of effort. Never used any of them before broadband became a thing (actually we converted the sewing cupboard to a computer cupboard, so dial up was done with a long phone extention cord we ran through a roofspace...).

Same house had wiring for ceiling fans added for future proofing. Ultimately ended up having heat pumps installed instead, and never will have a ceiling fan... Again future proofing money down the wire.

Dryer - vented dryers are a no-no in passive houses. Which makes me sad as the payback period for a heat pump dryer is stupid long. And even worse for a condensor dryer. Could still do another motorised damper with makeup air... 🤔

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Kickinbac

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#3369017 29-Apr-2025 22:23

Could you put the drier in the garage? I’m assuming the garage is not part of the air tightness envelope?

Twincamr2

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#3369056 30-Apr-2025 07:53

Kickinbac:

Could you put the drier in the garage? I’m assuming the garage is not part of the air tightness envelope?

You're correct and that's a very good thought. It would be extremely hard to get past the board of directors though. Just had a look at prices of heat pump dryers and I'm out of touch. They're much more affordable than I thought - $1k less. That's probably what we'll do.

Scott3

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#3370083 3-May-2025 00:19

acsylaa:

Scott3:

Another little thing, my general power circuits have 16A breakers. Many modern homes have 20A breaker. Suggest going for the latter, for reduced risk of tripping again.

There is more than likely a reason for that, one of them being that your power points are fed by a 1.5mm cable, or that the cable has been de rated for a reason if its a 2.5mm to a 16A MCB.

You cant just install a 20A breaker on any power circuit to solve nusance tripping as you could over rate the cable and burn the cable out, the fusing factor would have changed so wont trip with in the required time for the cable rating, the list goes on.

Given the house is a new build, and on the assumption that OP has a competent Sparky doing the install, requesting 20A breakers will see the appropriate wire size installed. As you say, not something that can be retrofitted.

Scott3

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#3370085 3-May-2025 00:38

Twincamr2:

Scott3:

single phase RCBO's cost the same regardless of capacity (based on the below link at least...)

https://eurotechnz.co.nz/products/rcbo-schneider-resi9-slim?variant=45841093689592

So the extra cost driver is the fatter cable.

Good on you for supporting local. EVnex are really pushing forwards when it comes to smarts.

I brought a 2nd hand EO Mini Pro 2. In theory a great solution, but not in practice. The smarts are dependent on the charger connecting to EO's servers, Initially they had a 3+ month restructure, where I had no access to support to resolve, then a they were quite helpfull for a couple of months but never were able to resolve the issue. Then they had advised me that my EVSE had dropped out of the support period and the smarts were no longer offered, so I now have effectively a dumb charger.... Avoid EO...

Great - no real downside! I guess you can install a standard 15 or 16A socket on that circuit.

I saw that there was a recent sale of EO gear and wondered if I should pick some up.

Speaking of current, how would I know what rating is for the mains coming into the house? The main breaker in the distribution box is 100A...

I don't know the regulations enough to advise if there is a maximum breaker size to have outlets on the circuit. If there is, it is OK to have the wire sized for 32A breaker with a smaller breaker incase a future upgrade is needed (easy to swap the breaker, hard to pull a whole new wire).

On 15A or 16A sockets, Avoid 15A for EV charging. While they are rated for 15A continuous, they do fairly poorly in this duty in the real world. When the first used import leaf's started arriving in NZ in 2012 & 2013, the norm was to smash apart the Japan plug (to preserve the thermal probe) and wire on a 15A plug. They would draw about 13A, and quite a few ended up blackened or melted. The 16A socket then became the norm, and there have been minimal issues with those.

I don't know how to find out your pole fuse size, I assume a sparky could call the lines company and ask? - With a 100A main switch there is the potential yours is 100A.

acsylaa

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#3370123 3-May-2025 08:46

Scott3:

I don't know how to find out your pole fuse size, I assume a sparky could call the lines company and ask? - With a 100A main switch there is the potential yours is 100A.

The pole Fuse Defanately wont be 100A! mas pole Fuse size in Residential is 63a by default unless its a old 10mm overhead or there has been a application to upgrade the mains and fuse rating to 80A, But then the Network provider will be asking questions and more then likely make you upgrade to 3 phase.

But this also comes down to the Providers in the areas as well, WEL 63A by default Counties are also 63A by defualt.

The 100A main switch is only rated for 100A Switching Capacity only and does not stipulate the Fuse size.

I run a 63A main Switch and a 50A MCB after the main switch, in the hopes that the 50A MCB will trip before the Pole Fuse does to save the hassle of Dealing with the Network and getting them out here to replace the pole fuse.

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acsylaa

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#3370125 3-May-2025 08:57

Scott3:

Given the house is a new build, and on the assumption that OP has a competent Sparky doing the install, requesting 20A breakers will see the appropriate wire size installed. As you say, not something that can be retrofitted.

Yes one would hope as i see a lot of sparkies now days doing Dumb things now days, as i suspect they aren't being fully trained in the right way of doing things or things arent explained to them in a way that they understand.

I just had a Disagreement with a Sparky yesterday about the way a device should be wired up and controlled as they were Switching the Neutral and using the Phase as a common return which is highly illegal and Dangerous!

Twincamr2

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#3371115 7-May-2025 12:12

Scott3:

Given the house is a new build, and on the assumption that OP has a competent Sparky doing the install, requesting 20A breakers will see the appropriate wire size installed. As you say, not something that can be retrofitted.

Hmm. Sorry if this is a silly question, but wouldn't specifying 20A breakers mean (along with heavier cable) a greater number of points on each circuit and fewer circuits? Or is that the intent?

Twincamr2

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#3371116 7-May-2025 12:15

Scott3:

I don't know the regulations enough to advise if there is a maximum breaker size to have outlets on the circuit. If there is, it is OK to have the wire sized for 32A breaker with a smaller breaker incase a future upgrade is needed (easy to swap the breaker, hard to pull a whole new wire).

On 15A or 16A sockets, Avoid 15A for EV charging. While they are rated for 15A continuous, they do fairly poorly in this duty in the real world. When the first used import leaf's started arriving in NZ in 2012 & 2013, the norm was to smash apart the Japan plug (to preserve the thermal probe) and wire on a 15A plug. They would draw about 13A, and quite a few ended up blackened or melted. The 16A socket then became the norm, and there have been minimal issues with those.

I don't know how to find out your pole fuse size, I assume a sparky could call the lines company and ask? - With a 100A main switch there is the potential yours is 100A.

We have a 15A socket in the garage which has the Tesla portable EVSE attached. This regularly draws the full 15A (at least according to the app). I haven't noticed any heat problems, but I'll have a look!

Twincamr2

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#3371118 7-May-2025 12:23

acsylaa:

The pole Fuse Defanately wont be 100A! mas pole Fuse size in Residential is 63a by default unless its a old 10mm overhead or there has been a application to upgrade the mains and fuse rating to 80A, But then the Network provider will be asking questions and more then likely make you upgrade to 3 phase.

But this also comes down to the Providers in the areas as well, WEL 63A by default Counties are also 63A by defualt.

The 100A main switch is only rated for 100A Switching Capacity only and does not stipulate the Fuse size.

I run a 63A main Switch and a 50A MCB after the main switch, in the hopes that the 50A MCB will trip before the Pole Fuse does to save the hassle of Dealing with the Network and getting them out here to replace the pole fuse.

Ah. So what are the chances of popping the main breaker if charging two EV's while baking something in the oven and cooking dinner on the induction hob, heat pump on, and doing some washing in the washing machine and dryer, coffee machine and toaster, fridge compressor running etc. ? Seems like a plausible scenario in winter...

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