EV Charger Risks: Home Charging Installation Risks and Advice [by Munro Live]

[Administrator]

Sponsored

 

[mystermykee]

What in the mother of.....

 

[philbur]

This is actually an important part of the whole charger issue - is it a charger defect or risks of weak plugs causing issues? Or a combo? I am definitely going to keep a closer eye on heat\wear of my plug moving forward and agree that some standards for 14-50 plugs is needed to keep things safe.

 

[tigerbalm]

Here in Ireland electrical regulations state that all EV chargers over 3kW – must be:

1. Hard-wired back to fuse board.
2. Have its own dedicated circuit that is RCD protected.
3. Have an emergency shut off switch (ugly) within reach of the charger.
4. Have the exact charging installation – including pictures – registered with the government regulator (called Safe Electric Ireland).

Doing all of the above does have the advantage of getting you a €600 government grant towards the cost of the installation/charger.

Typical installation:

 

[DerekS]

I couldn’t make it through the whole video, those guys took forever to get to the point.

But from what I can gather, sometimes crappy breakers or outlets fail, even when installed by electricians, due to not being rated for 100% duty cycles. Is that pretty much the gist?

 

[philbur]

I couldn’t make it through the whole video, those guys took forever to get to the point.

But from what I can gather, sometimes crappy breakers or outlets fail, even when installed by electricians, due to not being rated for 100% duty cycles. Is that pretty much the gist?

that Is pretty much it. Quality of plugs are not designed for high pull of an EV. Works for a dryer or welder. But an EV pulls lots more for longer. So we need more EV specific breakers and plugs. Also making sure it it properly installed makes a difference. Making sure wires are torqued to spec etc. it’s a good point overall As we scale EV adoption.

 

[whitex]

A group of old-timers raising alarm out over substandard and/or faulty electrical equipment. The plug which melted with a Porsche charger might have actually been PMC+/PMCC's fault as the prongs may have gotten hot enough to melt the plug. The other things are just faulty equipment, like the breaker which melted - it was a 60A breaker, so it was hardwired, it should be able to sustain 48A indefinitely. They mentioned a better quality NEMA 14-50 receptacle but that won't help you with melting breakers or junction boxes. Is Sandy removing his home Tesla Wall Charger until he finds a special "EV rated" distribution panel with EV rated breaker? Probably not.

Substandard or faulty equipment does exist. The guy in the middle only did EV installations for 3 years, so he only saw EV related failures. Had be been an electrician for a longer time, he would have seen equipment failures without EV's. Sadly the world is not perfect.

There is one thing they could have recommended, which I do with all of my installations. Run the install full throttle while monitoring all the fuses, junctions, wires, EVSE, all the way to the car with a FLIR camera. If you have faulty equipment, you are likely to see things heating up more than expected. Unfortunately such a test takes time, and if you have to pay an electrician per hour, it might be expensive.

 

[JRNJTAYCAN]

Oh good god is the video over yet I can't stop dozing off. I think these guys were sitting around smoking a joint and said hey let's make a safety video that would be pretty cool!

 

[DerekS]

Oh good god is the video over yet I can't stop dozing off. I think these guys were sitting around smoking a joint and said hey let's make a safety video that would be pretty cool!

Yeah, it was really a difficult viewing. My main takeaway was make sure your NEMA outlet is a Hubbell.

I haven't checked mine yet.

 

[Jhenson29]

Unfortunately such a test takes time, and if you have to pay an electrician per hour, it might be expensive.

Probably not necessary once we follow his suggestion to increase circuit sizes from 125% to… [checks notes] …130%.

Should be fine after that. /s

 

[whitex]

Yeah, it was really a difficult viewing. My main takeaway was make sure your NEMA outlet is a Hubbell.

I haven't checked mine yet.

Not just Hubbell, but the expensive version made of the special plastic. Hubbell has a regunal inexpensive version too (which I happen to use, but with Tesla EVSEs which don't try to melt recepticles like Porsche ones, I thought of upgrading but FLIR tells me they never get super hot).

 

[whitex]

Btw, I couldn’t help but notice how they were talking about people EV “newbies” make things worse by charging every day. This doesn’t make sense on many levels, but the point relevant here would be charging less often means longer charging sessions, which means greater chance of overheating.

 

[RAHRCR]

They actually made ALOT of relevant points in this video despite the low production value and tempo. As EV’s become more mainstream, all of the points/recommendations they made will become more relevant.

 

[DerekS]

They actually made ALOT of relevant points in this video despite the low production value and tempo. As EV’s become more mainstream, all of the points/recommendations they made will become more relevant.

Can you summarize them? I am way too type-A to sit through that entire thing.

 

[DougFrisk]

Been following the forums since August, but this thread convinced me to create an account.

I’ve seen this failure first hand with my electric furnace. Each of the four 50 amp breakers draws 37 amps continuously while the furnace runs. When it was first installed, I had an overheating situation in the service panel. One connection on one of the breakers was just bad enough that it overheated and burned the insulation on the wire about 8 inches out from the breaker. (#6 THHN connected to a Square D commercial breaker for those who were about to ask)

The connections at the breakers, any junctions, and at the outlet need to be installed nearly perfectly so they have as close to zero resistance as possible. It’s absolutely vital for high amperage continuous duty circuits like an EVSE or furnace.

The reason boils down to simple high school electronics and the equation Ohms of resistance = Volts / Amps.

To draw 40 amps on a 240 volt circuit the overall resistance needs to be 6 ohms. That includes all of the wiring, all of the connections and the load itself.

I suspect most here already know that a 240 volt 40 Amp EVSE is drawing 9.6 KW when charging. Most of that power is being converted to battery charge at the load, but any resistance in the wiring or connectors is being converted to heat.

If there’s 0.1 Ohm of resistance in one of the connections (that would be a lot) then two things happen. The total current draw drops to 39.3 Amps and 1.6% of the total power is being converted to heat at the bad connection. That works out to 153 watts of heat that needs to be dissipated at that bad connection.

The actual resistance at the bad connection is likely less than 0.1 ohm but the same thing happens if there's 0.01 ohm bad connection, then the excess heat would be closer to 15 watts so overheating to failure will take longer. 15 watts of heat being generated inside an EVSE 14-50 plug where the blade connects to the wire would be enough to make the plug too hot to touch pretty quickly.

15 or even 150 watts may not sound like a lot, but it’s concentrated at a small connection that’s inside a closed box with no air circulation so it continuously gets hotter while the power is on. It doesn’t take long to get to the situations described in the video.

You don’t see this problem with other circuits in your house because they’re lower amperage and aren’t run continuously. A 1500 watt hair dryer is going to have 6 times the resistance at the dryer itself as the 9600 watt EVSE, so the bad connection will generate about 1/6 the heat, but only while you dry your hair, so even though the connections might start to heat up at the socket or breaker it will cool down again.

I was lucky with my furnace, because the heat generated at the breaker connection caused the breaker to trip. In the junction box and 14-50 socket in the video the heat was far away from the breaker so they just got hotter until they failed.

I suppose the practical upshot of the video is, home run hardwire your EVSE if possible (that removes the connection at the back of the socket and the plug/socket connection and the connection in the plug from the blades to the wires) and make sure the electrician installing it torques the connections correctly.

The suggestion for a specialized EVSE breaker is most likely overkill. As long as the wiring is done correctly to spec everything should be perfectly safe. An EVSE breaker doesn't even remove the most likely failure which is the electrician not torquing the connections correctly.

Sponsored