Check your home electrical connections, friends

[mikehmb]

PSA - reminder for everyone to do a check-up on your EVSE infrastructure if you've got it at your house.

Some of you will recall I had Mr Melty (electrician used a residential-grade NEMA 14-50 the first time. which subsequently melted in the wall), and the concerns put out by Munroe et. al. regarding breakers frying because of loose connectors or not being rated for continuous 40+ amp draw.

So - 3 nights ago, the breaker on my EVSE blew immediately after the charge schedule initiated at midnight. In the morning, I tried again - blew within 5 minutes. I didn't have time to debug leading up to NYE so I just charged at public infrastructure until today.

Took a look at the breaker, and the lugs were absolutely loosened up, presumably from heat cycles and time. A quick crank-down and it's been running at full-tilt for the last 30 minutes.

TL;DR - do a once/year checkup on your electrical connections for your EVSE so nothing gets melty.

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[godfodder0901]

PSA - reminder for everyone to do a check-up on your EVSE infrastructure if you've got it at your house.

Some of you will recall I had Mr Melty (electrician used a residential-grade NEMA 14-50 the first time. which subsequently melted in the wall), and the concerns put out by Munroe et. al. regarding breakers frying because of loose connectors or not being rated for continuous 40+ amp draw.

So - 3 nights ago, the breaker on my EVSE blew immediately after the charge schedule initiated at midnight. In the morning, I tried again - blew within 5 minutes. I didn't have time to debug leading up to NYE so I just charged at public infrastructure until today.

Took a look at the breaker, and the lugs were absolutely loosened up, presumably from heat cycles and time. A quick crank-down and it's been running at full-tilt for the last 30 minutes.

TL;DR - do a once/year checkup on your electrical connections for your EVSE so nothing gets melty.

An add on to that; the lugs reguire a specific torque. Get a good tourqe driver and lookup the required torque value when tightening.

 

[CrazyOne]

PSA - reminder for everyone to do a check-up on your EVSE infrastructure if you've got it at your house.

Some of you will recall I had Mr Melty (electrician used a residential-grade NEMA 14-50 the first time. which subsequently melted in the wall), and the concerns put out by Munroe et. al. regarding breakers frying because of loose connectors or not being rated for continuous 40+ amp draw.

So - 3 nights ago, the breaker on my EVSE blew immediately after the charge schedule initiated at midnight. In the morning, I tried again - blew within 5 minutes. I didn't have time to debug leading up to NYE so I just charged at public infrastructure until today.

Took a look at the breaker, and the lugs were absolutely loosened up, presumably from heat cycles and time. A quick crank-down and it's been running at full-tilt for the last 30 minutes.

TL;DR - do a once/year checkup on your electrical connections for your EVSE so nothing gets melty.

I asked my electrician about 100% duty cycle breakers and he said that they are available only for commercial panels. Mounting the breaker away from others is the best we can do. We can also lower the max charge rate or use an uprated EVSE.

Torquing the connection is a good idea, but I haven't done it.

 

[mikehmb]

I asked my electrician about 100% duty cycle breakers and he said that they are available only for commercial panels. Mounting the breaker away from others is the best we can do. We can also lower the max charge rate or use an uprated EVSE.

Torquing the connection is a good idea, but I haven't done it.

For sure. I should clarify in my setup, the EVSE goes to a 50a breaker on a breakout box, then into the main panel on a 100amp breaker shared with another circuit, so in theory the 50a should go first, and the 100 should be good for many years.

In my case, the 100a needed to be re-torqued, and I'll double check the 50a breaker later today after I get charged up.

 

[Stevetom84]

For sure. I should clarify in my setup, the EVSE goes to a 50a breaker on a breakout box, then into the main panel on a 100amp breaker shared with another circuit, so in theory the 50a should go first, and the 100 should be good for many years.

In my case, the 100a needed to be re-torqued, and I'll double check the 50a breaker later today after I get charged up.

In theory the 50A should trip before the 100A, but you could go deep in a rabbit hole on breaker coordination. I'm in the electrical field and while not common a higher amperage upstream can trip before a downstream lower amp breaker. Most facilities this isn't an major issue since it's typically nuisance tripping, but in healthcare we have to do the full blow coordination studies to prevent something like a floor cleaning machine tripping an upstream breaker serving an operating room.

 

[COdogman]

Mr. Melty would be a good name for a grilled cheese restaurant.

 

[Joules Burn]

 

[beatle]

Some fasteners need a torque value higher than what that driver tops out at. The EVSE rated Leviton 14-50 recently posted in another thread needs 75 in/lbs.

While it's good to check your breaker and connections, using an IR thermometer can be a quick way to see if Le Résistance is at risk of melting your receptacle or tripping your breaker. Breakers can also trip from high temperature and not just over current. I found once I melted and subsequently replaced my receptacle that the breaker started to trip from the same cause: heat-cycled loose terminal screws.

 

[edwjmcgrath]

I'll reinforce this. The power-up self test on our Porsche mobile charger plus threw an error after working fine for several months. I opened it up to torque down the bolts and one of them was stripped. With a little tug the wire came out. This is now the third Hubbell that I've had problems with (although this one could have been an overly aggressive sparky). I know that they are from the same manufacturer, but I'm going with Bryant now.

 

[Judd]

When I first got my home setup I charged at 40a and noticed how hot things were getting once summer and the Texas heat started. I checked all the connections and everything was tight, so I backed my charger down to 30a and it made a significant difference. Charging overnite, the lower power time didn’t make that much difference. So I’ve not turned it back up since it’s cooled off.

My point, just because you can…doesn’t always mean we should . Great reminder.

 

[Meltdwn]

Based on personal observation, a proper torque wrench is necessary. I used to work on engines and could get very close by feel, when checked with a torque wrench. For fun, I habd torqued my breakers and outlet on install and then with a wrench. I was way under. Bottom line, it’s worth the price to buy a proper range torque wrench and be safe.
I would also make sure a hired electrician does the same.

 

[Stevetom84]

When I first got my home setup I charged at 40a and noticed how hot things were getting once summer and the Texas heat started. I checked all the connections and everything was tight, so I backed my charger down to 30a and it made a significant difference. Charging overnite, the lower power time didn’t make that much difference. So I’ve not turned it back up since it’s cooled off.

My point, just because you can…doesn’t always mean we should . Great reminder.

We do the exact same thing - keep our EVSE set at 30A for overnight charging. If there is a fault or loose connection simply reducing the amperage won't save you, but reducing heat build up is always good for the longevity of conductor insulation. I tend to put a thermal camera on the breaker and plug every month or so to hopefully catch any potential issues before they become catastrophic.

 

[DCFC]

We do the exact same thing - keep our EVSE set at 30A for overnight charging. If there is a fault or loose connection simply reducing the amperage won't save you, but reducing heat build up is always good for the longevity of conductor insulation. I tend to put a thermal camera on the breaker and plug every month or so to hopefully catch any potential issues before they become catastrophic.

I only charge at as high of a current as required. Heat generation is to the square of current. 40A generates about 78% more heat than 30A. Some nights, I back all the way down to 10A because that's all that is needed to fill up by morning.

 

[eRacer]

Just a PSA about resetting breakers. As an engineer, it's almost a cardinal sin to reset a tripped breaker without finding out what tripped the breaker. It's best to investigate what caused the breaker to trip before trying to reset it. The breaker is made to be the "weak link" within the circuit in a electrical fault scenario. You never know if it will still remain that way after resetting it. Don't become a Mr. Melty yourself.

 

[Stevetom84]

Just a PSA about resetting breakers. As an engineer, it's almost a cardinal sin to reset a tripped breaker without finding out what tripped the breaker. It's best to investigate what caused the breaker to trip before trying to reset it. The breaker is made to be the "weak link" within the circuit in a electrical fault scenario. You never know if it will still remain that way after resetting it. Don't become a Mr. Melty yourself.

Good advice for any breaker that trips out of the blue, not just your EVSE.

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