Chevy Bolt EV Forum banner
21 - 40 of 50 Posts

·
Registered
Joined
·
4 Posts
You left some information out about the stock EVSE. It should also have an amp rating along with the voltage rating. Per NEC, you can't have a load connected to a circuit that is larger than the allowed 125%. This code is written to protect against fires and property damage. When a load is protected by too large of overcurrent protection, the end result of a device failure is fire instead of a tripped circuit breaker.
 

·
Registered
username LT
Joined
·
868 Posts
I think my concern comes from future considerations. You have a 14-50 outlet. You give it a dual breaker for 240V of 15 amps and 3/14 cable (say) and you wire up your nifty adapter to the OEM EVSE. Someone comes along and sees that 14-50 and plugs in their range (or whatever). What goes first...melt the cable or trip the breaker?
So I would suggest the right outlet matched to the right size cable for the right length with the right breaker so that end to end is doing what it's supposed to and can do.
And I won't mention whether there's load capacity in the panel.
 

·
Registered
Joined
·
10,647 Posts
Why? The OEM EVSE internals were designed to accept 120-240VAC 50-60Hz to make it compatible with international markets. In the US, it has a 5-15P on it. Easily changed to a 15-50P, but you lose the plug's thermal protections doing so. I'd think that plugging an OEM EVSE into a 14-50R would give a much larger contact area, and thereby reduce the chances of a high-resistance heat-generating connection.
I believe Mateo1147 is referring to the hugely oversized breaker. In reality, if the onboard charger, or the J1772 handle were to short, the breaker would see way more than the 40 amps needed to trip it. I know the Bolt has a thermistor watching the charge port temperature, and the car is surely watching the onboard charger too. If either of those turned into a low wattage toaster, the car would likely shut the charge down, even if the breaker didn't trip. But Bolt2019 is correct, the stock EVSE, run on 240 volts, should have a 15 amp breaker.
 

·
Registered
2017 Bolt Premier
Joined
·
1,207 Posts
The outlet is 50 amp. Wouldn't one install required cable and matching breaker for that?
I understand the math. Your post is helpful to clarify the rules though.
40/50 amp circuits are a special case. When there is a single outlet on a circuit, in general the breaker and wiring must match the outlet. So, a 50 amp outlet would have a 50 amp breaker and wiring that carries 50 amps of current.

But there isn't a 40 amp outlet. There is a 14-30 and a 14-50, but no 14-40. The exception in that case is that a 40 amp circuit and breaker can carry the oversized 14-50 outlet. The premise is that the circuit breaker protects the wiring in the walls, so even if one plugged in a 50 amp device into the outlet, that the breaker would trip.

BTW that's why the example you later posted of a 14-50 connected to 14 gauge wiring and a 15 amp breaker is against code. A NEMA 14-20 receptacle does exist and is the next larger size for that wiring and breaker. That is what should be used as opposed to a 14-50.

ga2500ev
 

·
Registered
2017 Bolt Premier
Joined
·
1,207 Posts
I believe Mateo1147 is referring to the hugely oversized breaker. In reality, if the onboard charger, or the J1772 handle were to short, the breaker would see way more than the 40 amps needed to trip it. I know the Bolt has a thermistor watching the charge port temperature, and the car is surely watching the onboard charger too. If either of those turned into a low wattage toaster, the car would likely shut the charge down, even if the breaker didn't trip. But Bolt2019 is correct, the stock EVSE, run on 240 volts, should have a 15 amp breaker.
Why? The breaker is about protecting the wiring, not the plug in device. I have a 6W LED lamp sitting in front of me. It's on a 20 amp circuit. I would not reduce the circuit breaker to 1A because of the low power of the device plugged in. Why would an EVSE be any different than that?

ga2500ev
 

·
Registered
username LT
Joined
·
868 Posts
But Bolt2019 is correct, the stock EVSE, run on 240 volts, should have a 15 amp breaker.
Ok, sure. 240/15 breaker, 3/14 cable up to 60', 6-15 outlet. Make the adapter and that's that. But that's just to make it only for the OEM EVSE. We would all like to do wiring once. So go all the way to the standard 50 amp end to end.

ga2500ev: I wasn't suggesting that. That was an example of how it's wrong with the assumptions made in the conversation.
 

·
Registered
Joined
·
10,647 Posts
Why? The breaker is about protecting the wiring, not the plug in device. I have a 6W LED lamp sitting in front of me. It's on a 20 amp circuit. I would not reduce the circuit breaker to 1A because of the low power of the device plugged in. Why would an EVSE be any different than that?

ga2500ev
Because your LED lamp isn't as likely to burn down the house? I know, I'm reaching here. :unsure:
 

·
Registered
Premier, Yo, with every goodie!
Joined
·
1,455 Posts
If your dingleberry device goes bad and is drawing 17 amps on a 20amp circuit it will happily smoke and flame, and who knows what else, until it draws more than 20 amps, or until you are alerted by some means....

Again:

Circuit Breakers are there to protect the wires in the walls.
It knows not what is happening with the current, as long as it's less than its rating.
 

·
Registered
Premier, Yo, with every goodie!
Joined
·
1,455 Posts
An actual short in any device will trip the breaker. This is not an insignificant function of circuit breakers.
If it's a complete short to the chassis ground of the device, then the breaker pops.
If it's a gradual failure/short within the Dingleberry, then heat, smoke, fire can happily happen before the breaker pops when it finally starts drawing more than the breaker rating.
 
  • Like
Reactions: GregBrew

·
Registered
Joined
·
7,545 Posts
I do take issue with plugging a level one charger into a 14-50 receptacle. If there were ever an equipment failure it would probably be pretty impressive.
There's always the possibility that stuff doesn't work as designed, in which case all bets are off. But the house circuit is protected by the circuit breaker and the EVSE is protected by its own internal fuse. If you plug an EVSE that's not capable of 240V operation (in other words, some EVSE other than the one that came with the Bolt) then it'll just die as its fuse blows. Not particularly impressive.
 

·
Registered
Joined
·
252 Posts
The outlet is 50 amp. Wouldn't one install required cable and matching breaker for that?
I understand the math. Your post is helpful to clarify the rules though.
It is within code to use a 40a breaker with a 14-50 receptacle. As far as I know, this is done as a cost savings measure. I know from running these kind of circuits at work that the difference in wire cost from running a 40a vs a 50a can be $1,000.
 

·
Registered
Chevy Bolt 2020
Joined
·
3 Posts
The lack of the neutral is not a problem, as EVSEs don't use the neutral. But your 6-50 plug will not fit in a 14-50 outlet. Hot blades on the 6-50 are 1 inch apart. 14-50 is 1.375 inch.
I have used a 220 portable charger with a Y shaped adapter that allows me on. 30 Amp circuit breaker that is use for my electric clothes dryer or charge my Bolt. You cannot not do both st the same time and I post signs and Dymo labels do not to blow a circuit breaker. It was going to cost me $1000 to install a second 220 plug in the garage for $300 -500 charger .
$80 adapter and using a 25-28 amp 220 charger made economic sense
 

·
Registered
Joined
·
252 Posts
Because your LED lamp isn't as likely to burn down the house? I know, I'm reaching here. :unsure:
The computer I am typing on now is drawing about 150 watts from a 20amp 120v outlet that could provide as much as 2,400 watts! It's fine, because the computer is only drawing 150 watts. Think of it like drinking water through a straw from a small glass. Now drink water from the same straw but from a large glass. Are you going to drown? No, because you are only drawing water at the same rate as you were before.

It is more dangerous to be closer to your breaker's rating. Same goes for the wiring and the receptacle. I'd much rather have my toaster plugged into a 20 amp outlet than a 15 amp outlet. Maybe that's why you have to have 20 amp outlets in a kitchen nowadays.
 

·
Registered
2017 Bolt
Joined
·
9 Posts
I have a reservation at an air bnb that offers EV charging. When I asked about the type of charger she sent me this photo (apparently she does not have a charger but does have 220 service) View attachment 38789 Notice 3 prongs. My outlet I use at home for my level 2 charger only has 2 prongs. View attachment 38790 Do you think I can plug my level 2 charger into her outlet?
I have been charging my Bolt from a "dryer outlet" like that since I got it. Just be sure you have the correct adapter and a big construction-grade extension cord if you have to use one.
 

·
Registered
Joined
·
3 Posts
I have a reservation at an air bnb that offers EV charging. When I asked about the type of charger she sent me this photo (apparently she does not have a charger but does have 220 service) View attachment 38789 Notice 3 prongs. My outlet I use at home for my level 2 charger only has 2 prongs. View attachment 38790 Do you think I can plug my level 2 charger into her outlet?
I bought this Max Green 5 pc. adapter cord set 2 years ago for my 2014 Volt, in case I was stranded some place away from public chargers.
 

·
Registered
Joined
·
3,463 Posts
I bought this Max Green 5 pc. adapter cord set 2 years ago for my 2014 Volt, in case I was stranded some place away from public chargers.
I read some of the questions posted for that EVSE. Lost a little bit of faith in humanity.
 

·
Registered
Joined
·
10,647 Posts
It is more dangerous to be closer to your breaker's rating. for the wiring and the receptacle. I'd much rather have my toaster plugged into a 20 amp outlet than a 15 amp outlet. Maybe that's why you have to have 20 amp outlets in a kitchen nowadays.
Granted. Our garage outlet is wired for a 90 amp circuit, but I have a 40 amp breaker for our 32 amp onboard charger. Way safer than one wired for 50 amp service, and fused with a 50 amp breaker. Much better to have more wire than you "need", and a breaker closer to your load.

If you knew you would only ever pull 150 watts from that outlet, a smaller breaker would be safer.
 
21 - 40 of 50 Posts
Top