I installed a JuiceNet Pro 40 in November and have been successfully been charging my Bolt until two weeks ago when the 60 amp breaker tripped. I have retried several times, starts out fine but trips breaker after 10-20 minutes. The only change I can think of is the weather is now hot. The switch that controls the JuiceNet is 50 feet from the breaker box. The breaker might be thirty years old. I sent a email to eMotor Works last week but have not heard back yet. Any suggestions would be appreciated.
JuiceNet Pro 40 tripping Breaker
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I have a EMW JuiceBox EVSE set up for 30 A on a 40 A circuit since 2015 but I never had problem with it. If you are a DIY, get a clamp-style AC ammeter, and measure the current of each 120 VAC line while your Bolt EV is charging to confirm the true amperage flowing. Also check the exact AC voltage supplied to the EVSE. If the line voltage is lower the Bolt EV may pull a bit more current.
I doubt the Bolt EV or the JuiceBox are the cause, since the JuiceBox uses less than 2 A for internal power, and the only items it has in the 40 A circuit are the relay contacts.
The original circuit breaker may be at fault if the temperature is affecting it. Check the wiring at the breaker for tight connections. A loose screw may generate resistive heating, so tightening the screws may solve the issue.
I doubt the Bolt EV or the JuiceBox are the cause, since the JuiceBox uses less than 2 A for internal power, and the only items it has in the 40 A circuit are the relay contacts.
The original circuit breaker may be at fault if the temperature is affecting it. Check the wiring at the breaker for tight connections. A loose screw may generate resistive heating, so tightening the screws may solve the issue.
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746 Posts
Over the years, with electrics going back to 73, I have noted the effect of all types of weather. Certainly, the expansion during hot weather, and contraction during cold weather can very dramatically affect the true connection. I have seen a simple half turn of a screw bite make all the difference in the world. Start with rechecking and tightening every connection. That may do it. If not, like has been said already, get the electrician out there.
2017 Premier, new battery, 1993 GMC 2500, 2022 MYLR, 2017 M235i, Kubota B7100
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891 Posts
Over the years, I've had a few breakers go bad. It's rare, but it's easy enough (and cheap enough if it's not a discontinued line) to swap in a known good breaker to check the problem.
Is it fair to assume there is nothing else on that circuit?
Thanks for your help
118 volts between both hot legs and ground, 236 volts between the two hots. Just under 30 amps being drawn on both sides with the car at 120 miles of range. Only had it charging for a few minutes, will give it more time tonight when electrons are cheeper. Got no more than half a turn on any of the screws. Will see if I can get a full charge tonight, will change breaker if not.
Yea nothing else on circuit, will change breakers if it trips again.
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What wire gauge did you use, and why are you using an oversized breaker?
Breaker for an EVSE that draws 40 amps should be 50 amp, and wiring should be 6-gauge.
An oversized breaker can mask serious overload issues. Serious, as in your house could burn down.
Also, you mentioned a switch on the circuit. What’s the amperage rating on that switch?
It is 40 feet of 8- gauge wire and the switch box is 30 amp 600v. The wire and box were installed 30+ years ago to run a 5hp silo unloader motor. Was easiest place to quickly install the juice box, intended to run a 6 gauge wire and move it to garage but parking in silo room was working well.
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Umm....fairly certain that 8 gauge wire is way underspec for a 60 amp breaker. 8 gauge for a 40 amp breaker would be OK if you were using a 32 amp max EVSE. The fact the Juicebox 40 is a max 40 amp device means you would need at a minimum a 50 amp breaker and 6 gauge wire, applying the 20% buffer for continuous use devices.
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You have a 30 amp switch on a 60 amp circuit, and undersized wiring.
I’m pretty sure you already have a good idea what needs to be done, use the proper breaker, wiring, and switch for your 40-amp device.
If you’re comfortable doing it yourself the materials should run around $100.
I’m pretty sure you already have a good idea what needs to be done, use the proper breaker, wiring, and switch for your 40-amp device.
If you’re comfortable doing it yourself the materials should run around $100.
I concur. Replace the breaker and switch with new 40A devices, and charge your Bolt to your hearts content. I'd replace the (14-50R?) receptacle, too. It should only draw 32A from your 40A Juicebox, breaker, switch and wire, which meets NEC "80%" guidelines. Drawing any more than that could be problematic. It's not a future-proof solution, but it will get you through the next ten years or so.
FYI, In twenty years of driving and charging various EVs, I've had 40A breakers "wear out" over time (6 yrs-ish), on EV charger circuits. All of those electrons moving across copper contacts cause metal migration and accompanying corrosion over time. Basic chemistry/physics. Simply put, EV charging is rough on breakers. They're relatively simple to replace, and relatively cheap. If you're handy, careful, and respectful of 240V AC you can do it yourself. Double check everything, every time. Also, the old "one hand in your pocket and rubber-soled shoes" practice when working live circuits is a good one. Heck..it's even good for "dead" circuits.
My philosophy with electric circuits is the same as for firearms...ALWAYS assume they are "loaded".:nerd:
The 8 gauge wire won't hurt you at all for the current use. If the switch you refer to is something like a 30A fused disconnect, then that's probably okay as well - if you have 30A fuses in it. You're already aware the feed breaker should be changed to what 8 gauge wire can support - up to 40A depending on length.
I've been using 30A fuses in a fused disconnect for my 32A max EVSE for some time with no thermal issues - verified by IR camera. I would suspect yours will be similar.
Like you, I've not been able to verify over 30A per leg with a tong ammeter on the Bolt. It's close, but not there.
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JuiceNet Pro Tripping Breaker
If breaker is very old, I would recommend a licensed electrician's upgrade, ensuring that the wire to the breaker will accommodate 60 amps. Good luck.
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The Bolt won't charge at more than 30A regardless what EVSE is used, so a 40A breaker and 8ga. wiring is fine as long as he doesn't buy a car that draws more.
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juicenet says my bolt draws about 31.8A very consistently. That is still fine for 40A wiring and breaker. I set the app to limit it to 32A just in case I ever have a guest who charges some other vehicle.
I'm pretty sure it will charge at up to 32A on 240V.
Thanks to everyone for your comments. Bolt got a full (hilltop) charge last night but the temp. was in the low 60s. I did get a half turn on some of the screws. Would like to see where the extra 30 amps of heat was happening that tripped the breaker. Is there a way to lower the max rate to say 24 amps for extra margin of safety?
Yes. On the JuiceNet app, under Charging>JuiceNet>Settings, you can set the Maximum Rate (A) to your desired setting. It defaults to 40A.
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