Leviton EVSE issue

[n3ckf]

So i have a Leviton EVSE that ive had since probably 2013. Recently it started tripping the breaker when charging (after about 45 min).
What i see is that the energy supplied goes up (to higher than the charger ever uses) about 11-12KW and then the breaker trips.

I was replacing the charger today with another one i had (Siemens i used to use at my 2nd house that i no longer have) and i took the time to open it up.
No damage at all (in fact the inside of the electronics box was pristine) no "10k ohms" smell etc.

Has anyone debugged a similar issue? The charger looks perfectly ok (and i may swap the cable onto my existing charger since its longer/heavier than the one on my Siemens which is only a 30amp charger), so if i could "fix it" i'd probably put it back in service (i'm also charging a Model3 with it, so the difference between 7 and 10KW might occasionally matter).

[dstjohn99]

I have seen issues with house wiring and plugs for EVSE equipment. After the charger has run for an hour or more I check temperature at the breaker, plug and cables. I have found connections that become loose or oxidized mostly at the plug, but also the wiring connections at the breaker or inside the charger. Any issue like this will cause an increased current draw due to added resistance, and can ultimately lead to a fire.

https://photos.app.goo.gl/XBcaNCvojBieSX1t6

The photos shows an issue I found in my electric panel. I noticed that the main breaker was getting hot during charging, and after some investigation I discovered the poor connection and melted insulation.

[miimura]

As above, I would definitely look at all the wiring between the EVSE and the breaker.
Every connection should be checked for discoloration and tightness. If you still can't find anything wrong, disconnect the breaker, remove it from the panel and check the connection between the breaker and the panel. While it's disconnected, check the resistance between each hot wire and the other and between each hot wire and ground. There should be no measurable resistance between any of them, ie. open circuit.

[asavage]

Thing is, loose wiring and increased resistance may make heat, but what it doesn't do is cause increased current draw/flow.

While checking wiring for hot spots, loose connections (esp. screw terminals) and signs of overheating is SOP, what I'd be looking for is where the extra current is going. To ground? Across a short somewhere? An OBC defect (ie the car really is drawing more current)?

If visuals give no good clues, a clamp-on current meter is helpful.

[davewill]

As above, I would definitely look at all the wiring between the EVSE and the breaker.
Every connection should be checked for discoloration and tightness. If you still can't find anything wrong, disconnect the breaker, remove it from the panel and check the connection between the breaker and the panel. While it's disconnected, check the resistance between each hot wire and the other and between each hot wire and ground. There should be no measurable resistance between any of them, ie. open circuit.

I would suggest doing the same for the connections inside the EVSE and the charging handle. I just had one of my J1772 plugs (of about the same age) fail. The breaker had blown. It was badly discolored inside, and the insulation on the wires was burnt away.



I replaced it with, ironically, a Leviton plug and cable assembly.

[n3ckf]

yeah i definately dont have a problem in the outlet, wiring or breaker. (I can run the new EVSE on the same plug forever at 7KW for instance). I didnt take the actual cable and charging plug apart though which might be a thing to try. I looked for any discoloration in the EVSE when i took it apart, but didnt see any. Switching to a new EVSE meant a new cable too so if the cable was the problem i "fixed" it by doing that. Good ideas.