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2322 posts

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# 240744 24-Sep-2018 10:04
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I've got an electrician coming back to do more wiring in the garage (mk 2). Among a couple of other things, I need a 15 amp circuit for a new table saw motor.


We don't have an EV, but it seems very likely our next car (whenever that is) will be an EV. In the spirit of over-planning, I will run the wiring for charging that now while the walls are un-clad.


Power tools (welders, motors etc.) talk about 15 amp circuits, while EV threads (like this one) all refer to 16 (or even 32) amp circuits.


I think I've managed to figure out that a 15 amp socket is like a "normal" socket, but with a chunkier earth pin. A 16 amp socket seems to have a special connector of some description. Is that right?


Is there a difference in the wiring for a 15 vs 16 amp circuit? Given I've got no use for a caravan/other special connector right now, could I (say) put a 15 amp socket on the "EV circuit" and change it over to the necessary EV connector or even hard-wired wallbox if/when an EV arrives? 


Having both a 15 and 16 amp circuit assumes of course that the wiring to the garage is capable of handling two 15/16 amp circuits at the same time (unfortunately wiring is street --> house --> garage). If it can only handle one, is there some kind of socket/adapter that would let me alternate between EV charging and power tool usage? I'm comfortable that I wouldn't be able to charge a car at high wattage while welding simultaneously smile.


While my electrician is really good and I expect him to advise accordingly, I've found having a little knowledge myself can help a lot.

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3885 posts

Uber Geek


  # 2095353 24-Sep-2018 10:42

Put in as big a socket as your supply cable to the garage can handle. EV charging will need more power in the future. Put in a 3 phase socket if you are lucky enough to have 3 phase power in your garage already.

Just swap the plug on the table saw to a caravan type plug. They have become the defacto standard for 15A connectors anyway. Including on construction sites. Then you will only need a single 15A socket for both the saw and EV charging. Supposedly there have been problems in Australia with the 3112 type 15A plugs overheating. When used at max current for hours on end. As is typical for EV charging.

Also check the welders data plate. I bought a brand new welder that came with a molded type 15A plug. Yet the data plate said that the welder used 27A. So a 32A circuit was required to run the welder.

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  # 2095395 24-Sep-2018 11:45
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Technically a EV charging circuit needs a special type of RCD (Type B) on the switchboard, which are supposedly really expensive at the moment as they are still uncommon. So I would tell the sparky to call it a welding socket (whatever socket type you go for), and install a normal RCD (Type A). If you do get an EV, then the sparky just needs to swap out the RCD in the switchboard, and by then hopefully they will be more common and cheaper.


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  # 2095400 24-Sep-2018 11:49
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Most of my EV charging is done overnight via caravan plug on dedicated 16A line which goes back to the main switch board. Caravan plugs are used because they are common way of supplying 16A in the community all those camping grounds out there, I haven't seen too many 15A normal plugs but I'm not an electrician.

If you haven't got an ev in short term then charging for EV while using garage tools isn't a problem I imagine.

How difficult would it be to install a 32A line to garage?

Alternatively would it just be a case of never using tools while you are charging your car?

Personally I'd go for a 32A supply if you've got walls down.

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  # 2095415 24-Sep-2018 12:06
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Have you talked to your sparkie about having a sub main circuit board in your garage, with its own circuit breakers?


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  # 2095439 24-Sep-2018 12:39
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Thanks all. Follow up queries, if I may:


Are all caravan plugs standardised, or should I ask for a particular specification? 


Will see about wiring for 32A. Am I right in saying that (so long as the voltage is right) a device will only draw the amps it needs. i.e. I can plug something requiring 15A into a 32A circuit? Obviously not vice versa.


@darthkermit - Good point re the sub board. I am pretty sure the electrician was going to do this anyway, but def useful to confirm.


The house used to be two flats (with two ovens) so the switchboard supports three phase power. Last time the electrician was out we investigated bringing that three phase out to the garage, but unfortunately the wiring to the garage apparently wasn't chunky enough for three phase so would have required a complete rewire which wasn't worth it at the time. From what I can gather, the house was converted to two flats well after the garage was built, so I assume that the house bit of the wiring was upgraded then but they didn't bother to extend that to the garage. The connection from house/main switchboard to the garage will be the chokepoint.

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