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JuiceBox 40 cable heat

nateads

Member
Mar 7, 2020
14
4
Markham, ON
I'm reaching out hoping someone else might have some info on this. My JuiceBox 40 cable (the one that connects from the EVSE box to my NEMA 14-50p plug) gets warm when charging my cars. I change a 2017 IONIQ and a 2021 M3. The cable gets warm closer to hot. Not so hot that I cannot hold it, though the closer I get to the plug the hotter it feels.

As a note: I am not referring to the cable that connects to the car, all of the cable, handle and adapter, seem cool to the touch. The issue resides in the NEMA 14-50p connector. Nothing else emits heat, not even the 6AWG line from my 50amp 240V break to the plug box. Only the JuiceBox plug and cable.

Has anyone else encountered this problem? I find the Tesla get the cable hotter than the IONIQ, I assume it's the charging speed.
 

davewill

Active Member
Feb 5, 2014
1,821
1,964
San Diego, CA, US
Cheap 14-50 outlets or bad connections are a common problem. The Leviton branded 14-50s that are available for under $10 have been notoriously bad. No matter what quality outlet, if the connections aren't tight or if the insulation on the wires is pinched in the connection, you can have poor connections that overheat. You should inspect the connections to see what's going on.

Unplug the Juicebox, turn off the circuit breaker, and remove the cover from the outlet. See if there's any signs of overheating such as melting, scorching, discoloration of wires. If you can't see well enough, unscrew the outlet and gently pull it out of the box until you can see all the connections. If there's any signs of trouble you should replace the outlet (or have it replaced) with one of the Hubble ones.

https://www.neobits.com/hubbell_hbl...72nR80O8dm7o_4g2pjafQ5TAaOAm7RzsaAu96EALw_wcB
 

nateads

Member
Mar 7, 2020
14
4
Markham, ON
Cheap 14-50 outlets or bad connections are a common problem.
Took apart the box and plug, everything looks brand new and it's over 3 years old used almost daily. I don't get the feeling the issue is the plug as it never gets hot. The line going from the breaker to the plug box is cool to the touch.

The only thing I can think of is the line going from the breaker to the plug box is 6AWG and the plug from the evse to the plug box is 10AWG. I'm going to try setting my M3 to charge at less than 32 amp. Can anyone else confirm if there JuiceBox 40 uses a 10AWG plug it better?
 

EVDRVN

Active Member
May 12, 2018
1,411
1,700
North Bay Area
Are your terminals on the plug or the outlet oxidized? Is there any stress on the plug head or insulation on the cable that could have compromised the cord inside? I picture helps.
 

nateads

Member
Mar 7, 2020
14
4
Markham, ON
Are your terminals on the plug or the outlet oxidized? Is there any stress on the plug head or insulation on the cable that could have compromised the cord inside? I picture helps.
Zero oxidization on plug and terminals. Cord is essentially strait zero bending or twisting. Evse is indoors so I would be surprised if there was weather abuse. If there was any damage to the plug in assuming the built in GFCI would trip. IMG_20210227_210545.jpg
 

EVDRVN

Active Member
May 12, 2018
1,411
1,700
North Bay Area
I would check that the terminations on the outlet in the box are clean and tight on the copper. If that's ok you may look inside the EVSE for a bad connection which is something I'm not sure you have mentioned and very possible.
 

user212_nr

Active Member
Aug 26, 2019
1,407
739
US
I don't get the feeling the issue is the plug as it never gets hot.

If the plug does not get hot and just the cable, then it is probably just a normal thing. Wires are usually rated for 75C-90C 167F-194F which is almost enough to boil water.

The 10AWG is probably closer to its limit, hence it being hotter than your 6AWG wires.
 
Last edited:

TheRFMan

Member
Dec 15, 2019
336
258
Ottawa, Canada
plug from the evse to the plug box is 10AWG

10AWG seems like rather small wire for 40A, even for a short distance. I don't think electrical code applies as it is considered part of the appliance, but in the electrical code, 10 AWG in-wall wire is only rated to 30A max, 24A continuous. The 6AWG circuit is fine, that would not be the issue.

Has the wire always felt warm when charging? If so, it may be more of a design choice than a defect. If you can hold it without burning yourself, it may very well be within operating specification. Most electrical wires, plugs and outlets are rated for temperatures up to at least 65C, sometimes 75C.

As an electrical engineer, I don't like equipment getting hot though, and I'd probably back down the charge rate to 24A or unless you really need to extra charging speed.
 

TheRFMan

Member
Dec 15, 2019
336
258
Ottawa, Canada
The RMMan says 65C/149F max for most appliances

Just to be clear, I'm not talking about a limit in a code or standard, but rather of the rating on the plugs, outlets and wires themselves. For example, my 14-50 outlet, which looks a lot like the OPs (outlets here in Canada have built-in cover plates like that), has a 75C rating stamped on it.
 

nateads

Member
Mar 7, 2020
14
4
Markham, ON
The 14-50 plug wire has a stamp on it starting 100deg or so (I can confirm tomorrow morning I know it's 100+). The wire gets hot but not hot enough that I cannot hold it continuously. It's always been warm when in use, I've tested with a 2017 IONIQ, 2015 LEAF and 2021 M3. It gets the hottest with the M3 but that's because it pulls the most. I am going to use TheRFMans suggestion and drop my charging amps in the car. I've also contacted EnelX to find out how hot is to hot. I'll follow up on this post with my findings.
 

leonar40

Member
Jan 6, 2021
189
98
Bloomington, IN
My Clipper Creek charger gets to 105 deg F cable temp, but only in one spot, where the cables lay over each other at the top of the charger. The rest of the cable is just room temp. I added a small hook at the bottom of the wall and that allowed me to loop the charge cable over the charger more loosely with less overlapping sections and that lowered the overall temp.
 

MN-MS100D

Member
Dec 10, 2018
101
66
Minnesota
@nateads: Normally, I would be the one raising red flags, but I do not think you have a problem. You are doing the absolutely right thing by monitoring heat on your cables and home wiring. Juicebox has decided to go with 105C insulation wiring on their plug cord, so it is designed to run hotter without melting the cord and it has been tested to the max amperage when it went through UL listing process. Some manufacturers use higher gauge wiring in their plugs to reduce heat and losses, but apparently JB went with the smallest cable allowed to save a few dollars.

Keep an eye (thermometer) on it and make sure it doesn't get warmer, especially this summer.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,018
6,942
Boise, ID
The only thing I can think of is the line going from the breaker to the plug box is 6AWG and the plug from the evse to the plug box is 10AWG. I'm going to try setting my M3 to charge at less than 32 amp. Can anyone else confirm if there JuiceBox 40 uses a 10AWG plug it better?
10 gauge?!?! Seriously? I'm kind of angry at them just thinking about this, that they intentionally decided to build a device to use 40A continuous current draw and only used extremely undersized 10 gauge conductors. Regardless of how short, that's dangerously thin and resistive for that level of current. I'm not surprised at all that it feels hot. I would definitely keep the current turned down into the 20's, probably 24A, since 10 gauge is normally used for 30A circuits.
 

nateads

Member
Mar 7, 2020
14
4
Markham, ON
10 gauge?!?! Seriously? I'm kind of angry at them just thinking about this, that they intentionally decided to build a device to use 40A continuous current draw and only used extremely undersized 10 gauge conductors. Regardless of how short, that's dangerously thin and resistive for that level of current. I'm not surprised at all that it feels hot. I would definitely keep the current turned down into the 20's, probably 24A, since 10 gauge is normally used for 30A circuits.
I agree. I was confused when I saw that number but the install guide requested 8AWG but 6AWG is recommended. Seemed like a bottle neck to me.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,018
6,942
Boise, ID
I agree. I was confused when I saw that number but the install guide requested 8AWG but 6AWG is recommended. Seemed like a bottle neck to me.
This seems so egregiously out of line to me, that I can't imagine a company doing that. I mean this is for a device that's supposed to pull 40A continuous from a 50A circuit. So I'm wondering if something is being confused. It would be very likely for ONE of the wires in the cable to be 10 gauge. With 6 or 8 gauge cable, they do commonly use 10 gauge for the thinner ground wire that is included. That ground would be either green insulation or bare wire. Was this really both hot wires that were 10 gauge, like with black/red kind of insulation colors?
This just seems crazy to me, because for 50A circuits, you can't even use as small as 8 gauge if it's Romex cable.
 

nateads

Member
Mar 7, 2020
14
4
Markham, ON
Sorry I just realized my responses aren't making sense. I misread. I believe the main cable itself is 8AWG. What I am lost on is why they would ask for 8AWG from the breaker to the plug box but 6AWG is recommended on a 50amp breaker? Shouldn't the plug cable be 6AWG as going 8AWG creates a bottle neck, thus creating heat? I have taken everyone's recommendation though and dropped the cars charge rate to 24amp as it will charge over night and we never go below 40%. I'm getting the impression from the replies, heat is a normal byproduct to using these chargers and it's mainly because it's cost affective and they feel since the car cannot do over 40amp continuous it should be fine.
 

DMC-Orangeville

85D and John Deere 5100E
Feb 14, 2015
938
1,154
Orangeville ON Canada
Well, Juicebox is made in Canada - just down the street from the OP, in Vaughan. UL tested to CSA standards (cUL). Technically, 10 AWG cable rated 90C and higher can handle 40 amps per CEC table 2(with caveats), but a constant 40 amp draw WILL heat it to close to 90. I agree with @Rocky_H, bad design choice by the manufacturer; they should have used an 8 AWG, minimum, cable.

EDIT: I saw your post after I posted. I'll explain further, next post
small-juicebox-1.jpg
 
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Reactions: Rocky_H

Rocky_H

Well-Known Member
Feb 19, 2015
6,018
6,942
Boise, ID
Sorry I just realized my responses aren't making sense. I misread. I believe the main cable itself is 8AWG. What I am lost on is why they would ask for 8AWG from the breaker to the plug box but 6AWG is recommended on a 50amp breaker? Shouldn't the plug cable be 6AWG as going 8AWG creates a bottle neck, thus creating heat?
Oh, well that answer is easy about 6 or 8. I'm more concerned about what is 10 gauge though.

Look at this ampacity table that shows the allowed current ratings for different wire gauge.
Ampacity Charts - Cerrowire

Look at the row for 8 gauge wire. See how under those first two columns, the 8 gauge is rated for up to either 40 or 50 amps? So this question of whether you can use it for a 50A circuit isn't just a "yes" or "no". It depends on the conditions of the installation--if someone is using Romex cable inside a wall (first column) or separate wires in conduit (second column).

Look at the row for 6 gauge. Those columns are rated for 55 or 65A. So can you use 6 gauge wire for a 50A circuit? Yes--always. So this is kind of the one simple answer factor. You can always recommend 6 gauge for a 50A circuit, no matter what type of install someone is doing.
 

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