Juice Box 40 and NEMA 14-50 outlet on the same line

[MonorailGold]

I had a 50 amp line professionally installed, from my circuit box (actually, a secondary box was added) and routed through our single-car garage. In the garage is an outlet (NEMA 14-50) that is compatible with the mobile charging kit that came with my MME. The same 50 amp line terminates at my outdoor-mounted Juice Box 40 (hardwired).

99% of the time, I'll be charging my MME outdoors (wife's car gets the garage). I opted to have the outlet installed in the garage to future-proof the setup, if/when we get a second EV. In that scenario, I would add a second Juice Box 40 and pair them together, so it charges one EV or the other.

Today, I tested my mobile charge kit and it worked as expected ... but about after ten minutes, charging stopped. I got a Juice Box notification that my charger was offline, and the Ford Pass app indicated that it was 'not charging.' I checked the circuit box and found that the line GFCI had tripped. I reset it and removed the mobile charger from the MME.

So, I'm trying to determine why the circuit tripped and how I can prevent it if/when I charge inside the garage with the mobile kit. I looked at Ford's website about the mobile charging kit and I *think* it's because the portable charger is spec'd for 240V/32A, and my Juice Box is set to 40A.

Is the solution simply to change my Juice Box settings from 40 amps to 32? Or is it potentially something more complex?

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[ChuckA]

It sounds like both chargers tried to charge at the same time. If you have 2 JuiceBox EVSE’s they can be paired so the 2nd one will standby until the 1st one finishes.

What you can do is program the JuiceBox to start charging with enough delay for the mobile charger to finish, say 6 hours. But I’m no expert.

 

[BubGump]

I had a 50 amp line professionally installed, from my circuit box (actually, a secondary box was added) and routed through our single-car garage. In the garage is an outlet (NEMA 14-50) that is compatible with the mobile charging kit that came with my MME. The same 50 amp line terminates at my outdoor-mounted Juice Box 40 (hardwired).

99% of the time, I'll be charging my MME outdoors (wife's car gets the garage). I opted to have the outlet installed in the garage to future-proof the setup, if/when we get a second EV. In that scenario, I would add a second Juice Box 40 and pair them together, so it charges one EV or the other.

Today, I tested my mobile charge kit and it worked as expected ... but about after ten minutes, charging stopped. I got a Juice Box notification that my charger was offline, and the Ford Pass app indicated that it was 'not charging.' I checked the circuit box and found that the line GFCI had tripped. I reset it and removed the mobile charger from the MME.

So, I'm trying to determine why the circuit tripped and how I can prevent it if/when I charge inside the garage with the mobile kit. I looked at Ford's website about the mobile charging kit and I *think* it's because the portable charger is spec'd for 240V/32A, and my Juice Box is set to 40A.

Is the solution simply to change my Juice Box settings from 40 amps to 32? Or is it potentially something more complex?

No expert and I’m kind of shooting in the dark, but I have heard of people having issues where the outlet is on a GFCI breaker. There is also a GFCI in the charger itself. Sometime when GFCI’s are “double stacked” they can trip. I’ve personally never had this happen. Is there a way to tell if a breaker blew because of too much current vs because of a ground fault?

 

[Mach-Lee]

Your circuit is against code because it has two endpoints and was not sized for both simultaneous loads. An EVSE has to have it's own dedicated circuit unless intelligent load sharing is employed.

https://support-emobility.enelx.com/hc/en-us/articles/360002651411-What-is-Load-Sharing-

You need to set it up so that both combined will never use more than 40A.

Technically both need to be hardwired and you cannot use a 14-50 outlet on the circuit. I would suggest hardwiring both and using the load sharing function.

 

[MonorailGold]

Thanks for the link to the Load Sharing info. I have reviewed it before but I'll take a deeper dive next.

 

[ChuckA]

Your circuit is against code because it has two endpoints and was not sized for both simultaneous loads. An EVSE has to have it's own dedicated circuit unless intelligent load sharing is employed.

https://support-emobility.enelx.com/hc/en-us/articles/360002651411-What-is-Load-Sharing-

You need to set it up so that both combined will never use more than 40A.

Technically both need to be hardwired and you cannot use a 14-50 outlet on the circuit. I would suggest hardwiring both and using the load sharing function.

Note that 1 of OP’s EVSE’s is the Ford mobile charger. It’s 32A and can’t be managed. It’s a waste to use the JuiceBox 40 set to 8A. Probably will take days to charge off of it.

 

[Mache65]

If I understood correctly, you were charging only one car at a time.

gfci can be temperamental, I would put a regular breaker and try. I do not know if mobile charger has built in gfci or not but if it does, doubling up gfci can trip the circuit

 

[khbkhb]

Thanks for the link to the Load Sharing info. I have reviewed it before but I'll take a deeper dive next.

Wallbox chargers collude (load sharing, not necessarily sequential ... as one tapers off, the other can ramp up, or more than 2).

As one of the previous posters noted, GFCI is a PITA, because you wind up with 2 ... and that tends to trigger false shutdowns.

 

[Mach-Lee]

Thanks for the link to the Load Sharing info. I have reviewed it before but I'll take a deeper dive next.

Note that 1 of OP’s EVSE’s is the Ford mobile charger. It’s 32A and can’t be managed. It’s a waste to use the JuiceBox 40 set to 8A. Probably will take days to charge off of it.

If he gets the load sharing set up with two hardwired JuiceBoxes, then they will both charge at 40A since only one EV will be charged at at time. If he plugs in a second car, then they will ramp to 50/50% or 20A each. When one car finishes then the second car reverts to the full 40A.

Also, switching both chargers to hardwired and eliminating the 14-50 outlet allows you to remove the problematic GFCI breaker that will cause nuisance trips.

 

[ChuckA]

I don’t want to be too negative, but I will be anyway. There is no way an electrician will pull permits and get OP’s 2 outlet solution passed by an inspector. Work not done to code.

He has a mobile charger on a 14-50 outlet in his garage and a JuiceBox 40 outside.

Solution without a major investment:
1) determine if you have an off peak charging window.
2) set the MME to begin charging at the start time for off peak, say 8pm - 2am
3) set the JuiceBox 40 to start charging at 2:15am

This way the 2 chargers will never be running at the same time.

Or do it right. Have your electrician pull the permits and separate the 14-50 240v outlet from the same 50A line as the JuiceBox 40. Install a 2nd dedicated 240v 50A line.

 

[mateo]

The OP only has one EV. Both chargers aren't being used simultaneously. That definitely wouldn't work. The hardwired JuiceBox likely has nothing to do with the problem. It shouldn't be pulling any electricity when nothing is charging.

Likely the GFCI isn't compatible with the Ford Mobile Charger.

 

[ChuckA]

Okay, I reread the OP’s comment and now understand it’s not 2 EV’s charging at the same time.

Maybe it’s another case of the pigtail not being seated entirely in the body of the Ford mobile charger. I know nothing about the GFCI as I never had that problem.

 

[Peaceowl]

My husband and I agreed that 32A was the safest thing to do. No problems at all. With the overheating problems this car can have and all the reading from this forum we decided to not take chances.

 

[ChuckA]

My husband and I agreed that 32A was the safest thing to do. No problems at all. With the overheating problems this car can have and all the reading from this forum we decided to not take chances.

I did the same with a JuiceBox 32. I charge from 45%-90% in 6.25 hours, off peak. It’s plenty fast for my needs. I get 24 miles added approx. per charging hour.

 

[MonorailGold]

Thanks all for the comments! I was using the mobile charging kit as a 'proof of concept' for any times I potentially may need to charge inside the garage vice outside.

If/when we get a second EV, I'll get a second Juice Box 40 and set them up as a pair, and upgrade wiring if necessary.

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