The "standard" car charger is usually overkill—but your electrician might not know that
The "standard" car charger is usually overkill—but your electrician might not know that
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132 comments
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Good video. Accurate information.
Two notes:
- For North American homes: I agree with the overlooked value of a downrated circuit for EV charging, but I don't think he talked about a possibly better option for downrating: Using an existing 120v circuit (at whatever current rating) already wired in the garage . Remove the outlet, install EVSE (charger), and swap the breaker for a 240v one (at a current rating matching the original. So if you have a 120v 15A circuit (white romex) you can use the exact same wire for a 240v at 15A. If you have a 20A (yellow romex) you would end up with a 240v 20A. You get more than double the speed of charging with zero new wires added, only changing the breaker and removing the old outlets. Note: If you have multiple outlets in your garage all fed from this same circuit, this would mean all of your outlets in the garage are now 240v and not usable for regular 120v items.
- He didn't like Smart chargers. Thats a valid opinion, but smart chargers can do some nice things that I like. Some will also talk to each other if you have two chargers, such as if you have two EVs. They can be configured to share the same wire to the breaker box, so you can plug both cars in at night, one car will charge, then when that is complete, the other will charge automatically without having to unplug one car and then plug in the other. It will charge the least charged car first ensuring the best balance of charge to both cars assuming both cars can't be charged to full in one night. If you have solar panels, some smart chargers can talk to the solar system and be instructed to only charge when there is excess power that would otherwise go to waste. It can do this automatically so if clouds go overhead and not enough juice is available from the sun, the charging stops. As soon as the clouds clear and there is an excess again, charging resumes automatically. For outdoor charging, you can also configure most Smart chargers to only charge you authorized cars. So you don't need to worry about someone rolling into your driveway when you're not home (or a bad neighbor) and running up your electricity bill.
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Running more than one outlet on a 220 circute is generally against us codes. It will work but don't do it.
I have a phev with only 30 miles of range - ofen I get home with a nearly dead battery and need to leave again soon - I want faster charging. I'm sure someone with 200 miles of range can be fine on 110 volt slow charging as there likely enough time over a week that it works.
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I think #1 is suggesting to move the neutral over to another hot phase and change the outlet to a 240v nema 6/three prong (I think) with two hots and a ground instead of the 4 prong.
The 240v at the same amps gives you higher watts so faster charging without an expensive new conductor. I'm
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The problem with #1 is that most garages only have one circuit for the outlets AND the garage door opener. Moving to 240v would fry the opener.
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Changing a 120v line over to 240 is likely also against code even if the physical cable can handle it. 120V cable is typically white/black/green, and the electrical code prohibits using the white one as a hot leg. That’s why 240V cable of the same AWG is red/black/green. The red & black legs both carry 120V.
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Code allows painting the white conductor black which is what i do. Or at least it did 10 years ago when I last checked.
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This.
That said, it's rare that only one or two outlets in a garage are tied to a breaker. Usually they're all on one circuit in older homes, in my experience.
If you can find a circuit like this, though, it's perfectly valid. Many chargers made for 110V also have a 230V/15 or 20 amp mode. My Mother-in-law's portable charger has a 230V NEMA 2-20 adapter that comes in the bag with it.
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A 240V 20amp circuit I think would meet the needs of 99% of commuters in the US. If your average miles/kWh is around 3.3 and you're charging at 80% of the 20amp breaker limit (as you should be), even factoring in 10% losses in power transmission, you're still charging somewhere around 11 miles per hour. Easy 100+ miles overnight with zero infrastructure change outside of a couple wire nuts and a cheap charger. Hell, depending on local codes, you might get away with slapping in a nema 6-20 receptacle to make it even easier...
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Hell, depending on local codes, you might get away with slapping in a nema 6-20 receptacle to make it even easier…
If you do a receptacle, you've got to then do a GFCI. Check out the price difference between a GFCI breaker and one that isn't. If you hardware the EVSE, you don't need GFCI because GFCI is built into nearly all EVSE. If we're doing this exercise to keep low costs, adding GFCI outside of the EVSE jacks up the price.
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Fair enough! Anyone with existing 240v receptacles of any kind is a lucky duck, regardless.
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Are they somehow more expensive in the US? 40A 230V rated ones cost something like 30-50 € around here which doesn't feel that expensive to me. I'll admit it's considerably more expensive (~4x the price) than a standard breaker, but it's still more like a rounding error in overall costs.
Although EVSE's projection doesn't require you to periodically trip the GFCI so it doesn't get stuck, which is a major plus.
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Are they somehow more expensive in the US? 40A 230V rated ones cost something like 30-50 € around here which doesn’t feel that expensive to me.
In my suggested hardwired 240V 20A EV charger the total parts cost is just the regular breaker on the left at about $18.
The suggested solution you had of putting an outlet in would have parts cost of $119 + the cost of the GFCI breaker, the outlet and the receptacle cover. So that solution is 660% more expensive.
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Ok, so the US-style GFCI-breakers are indeed a lot more expensive than similarly rated DIN-rail alternatives. TIL
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If it makes you feel better, I was shocked (pun intended) to learn this too, and I live here.
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#1 is a terrible idea if you ever need to hire an electrician in the future, plan on selling your house, etc. The National Electric Code prohibits using white, green, or grey wire for a hot/load connection. The 120V cable will contain a black wire for the hot connection, white for neutral, and green for ground. To properly convert it to 240V you would need a cable that consists of black & red wires for the two 120V legs.
If your home ever suffered an electrical fire then this sort of jury rigging is precisely the sort of thing any competent insurance inspector would spot, and insurance carriers would deny coverage for since it clearly isn’t code compliant, which means a licensed electrician didn’t install it and it wasn’t properly inspected.
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#1 is a terrible idea if you ever need to hire an electrician in the future, plan on selling your house, etc. The National Electric Code prohibits using white, green, or grey wire for a hot/load connection. The 120V cable will contain a black wire for the hot connection, white for neutral, and green for ground. To properly convert it to 240V you would need a cable that consists of black & red wires for the two 120V legs.
I'll be the first to admit I'm no certified Sparky, but wire relabeling is used in a number of situations fully in accordance with NEC. My understanding is that some of this is in NEC 200.7. It requires relabeling both ends, but I don't think there's any code violation with it. If what you're saying was true, wouldn't that mean any -2 NM (Romex) would be code incompatible with 240v loads? I don't think that's true.
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The "120 volt cable", assuming you mean NM-B aka Romex, is rated for up to 600 volts if you look at it closely. It is absolutely acceptable to use that wiring for a 240V circuit, as long as you wrap colored (not green) electrical tape around the white neutral wire to indicate it's another hot.
Yes, there are 3-conductor (plus ground) wires one can also use for switches and 240V circuits with neutral. That neutral can be used to have 120V and 240V together (your oven may use 240V coils, but the light bulb probably runs on 120). Doesn't mean you need to have it, if your 240V circuit doesn't need a neutral. My air compressor is just a motor that can run at 240, no neutral needed, and its outlet is wired up with the same kind of Romex used for a 120 right next to it (with black tape to indicate a second hot)
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For me the smart charger was a key feature, and I never understood why that is never talked about. I have 200a service which was plenty for one fully powered charging service, but with the likelihood of electrification in upcoming years I was hesitant to have two. It was pretty clear I needed to prioritize smart charging so I’d have that possibility.
I can also configure it to only charge my allowed vehicles, should that ever become an issue
So far my family only has the one EV, so we only need the one charger. But I like that if we needed a second charger it could be on the same circuit and they could dynamically share the power to maximize charging
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132 comments