I am considering a JuiceBox L2 charger and will probably install a 40 A plug for it as my house only has 100 A service and my electrical pane probably does not have the capacity for a 50 A circuit. The difference in price between the JuiceBox 32 and 40 is only about $50 and I was wondering if the JuiceBox 40 can be used with the 40 A circuit (32 A max current) in case I move or otherwise upgrade to a 50 A plug. There has to be a way to limit the power of the charger right?
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houbaviy
I am surprised the manufacturer told you this.
Some EVSEs have a hardware jumper or DIP switch that hard-locks a derated amperage setting -- the case would need to be opened and the setting manually reconfigured to make any changes. But I don't see any such setting in the Juicebox installation manual.
To rely on setting it in software... that's concerning.
In this example you're using a 40 amp box, connecting it to a 40 amp circuit, and limiting it to 32A in software. If that software setting gets reset -- by accident, due to power outage, software update, new phone, whatever, you could potentially have a scenario where the car is pulling 40 amps, on a 40 amp breaker, and the breaker won't trip because it's within limits.
Maybe that's just me being overly cautious, but it doesn't sound safe. I guess the fallback argument is that, per their instructions, both the 32A and 40A units require the same 8 gauge wire, so from that standpoint there's no difference.
Some EVSEs have a hardware jumper or DIP switch that hard-locks a derated amperage setting -- the case would need to be opened and the setting manually reconfigured to make any changes. But I don't see any such setting in the Juicebox installation manual.
To rely on setting it in software... that's concerning.
In this example you're using a 40 amp box, connecting it to a 40 amp circuit, and limiting it to 32A in software. If that software setting gets reset -- by accident, due to power outage, software update, new phone, whatever, you could potentially have a scenario where the car is pulling 40 amps, on a 40 amp breaker, and the breaker won't trip because it's within limits.
Maybe that's just me being overly cautious, but it doesn't sound safe. I guess the fallback argument is that, per their instructions, both the 32A and 40A units require the same 8 gauge wire, so from that standpoint there's no difference.
It wouldn't be a transient 40 amp load -- it would be continuous (greater than 3 hours). If it's 40 amps across a 40 amp breaker, it likely wouldn't trip. And there's a good chance it wouldn't be caught (who's going to complain their car is charging too quickly?)
The NEC 80% continuous load rule applies to the whole circuit, so that includes the breaker. Ideally the breaker, the panel, the receptacle, even undersized wire should be able to handle it. But this is a "worst case" kind of rule, and hey, circuit breakers melt, too.
But at the end of the day, if Enel X says you're good to go, they're the experts.
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The NEC 80% continuous load rule applies to the whole circuit, so that includes the breaker. Ideally the breaker, the panel, the receptacle, even undersized wire should be able to handle it. But this is a "worst case" kind of rule, and hey, circuit breakers melt, too.
But at the end of the day, if Enel X says you're good to go, they're the experts.
There's a case to be made for future proofing through -- not to accommodate larger batteries, greater daily distances, or less efficient EVs (although any of those could be true), but to expect that a household will become a 2 or 3-EV household in the not-distant future, and 80A with the right 2-cord EVSE would allow simultaneous charging.
That's good to see that notification, but...
(a) it's certainly not foolproof and actually kind of disturbing it could be clicked through by a random homeowner who is unversed in the specifics of electrical code requirements
(b) is it sticky? is there any possible way this setting can unintentionally reset to full amperage without the owner knowing?
As I said above I'm being overly cautious because the installation requirement as outlined calls for 8 gauge wire for both the 40 and 32 amp units, so it's not as if your walls are going to burn if this setting get inadvertently changed.
Same, sort of. Whichever car I'm driving usually charges at work, and the home charging is in use maybe once weekly. My 2-cord workaround, instead of 80A, was to install a second circuit I can plug my 16A L2 into to supplement the 40A unit. Know how many times I've used it in 18 months? Not once. But I'm sure there'll come a day...
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