Loose wires

[ai4px]

I found this video that shows how an electrical fire can start from a lose connection. Any of you charging using the stock charger (EVSE) on 120v should realize that most 120v outlets are daisy chained together. The outlet in your garage may be 4th or 8th in line from the breakerbox and you could have many connections along the way. Also, many contractors don't install the wires to the outlets by the screws, they simply stick the wire into a clip on the back which can become lose or corroded over time.

Be safe out there folks! Make sure that all connections in any daisy chained outlets are on the screws and are tight!

 

[eprosenx]

I found this video that shows how an electrical fire can start from a lose connection. Any of you charging using the stock charger (EVSE) on 120v should realize that most 120v outlets are daisy chained together. The outlet in your garage may be 4th or 8th in line from the breakerbox and you could have many connections along the way. Also, many contractors don't install the wires to the outlets by the screws, they simply stick the wire into a clip on the back which can become lose or corroded over time.

Be safe out there folks! Make sure that all connections in any daisy chained outlets are on the screws and are tight!

Yes! Thank you for this PSA! I talk about this all the time!

This is one reason the NEC says charging circuits must be dedicated with a single receptacle on them. I always recommend folks have a solid charging solution at home since that is where they charge the most.

Frankly, on the road is where this is most dangerous for many of us. I am currently writing this from my mothers beach house with my M3 plugged in outside at the far end of a 15a (voltage drops to 110v while charging at 12a) circuit. It took it all weekend to charge back up. I need to install a new main electrical panel here so I can put in a 14-50.

 

[thefortunes]

Thanks for the PSA, but ugh... the word is lOOse.

 

[roblab]

Yes, fires can happen, and that's why we use circuit breakers. The only instance I had of a short causing a fire, the circuit breaker turned it off and the fire went out inside the metal outlet box. I agree. Dedicated, 220-240 v circuit on a 50 amp breaker with a 40 amp load. Follow the rules.

 

[ewoodrick]

Yes, outlets can be daisy chained, but I don't think that you can do 4 let alone 8.

Garage outlets will generally only be one or two.

But yes loose wire, especially on high current circuits, can burn houses down

 

[Eno Deb]

Also, many contractors don't install the wires to the outlets by the screws, they simply stick the wire into a clip on the back which can become lose or corroded over time.

Even if you don't have daisychained outlets, it's worthwhile to check if the receptacles are worn out or corroded, especially if they are older. The outlet in my garage got quite warm when charging the car; after replacing it with a new one, it now stays cool. Also, it's best to use a so-called "commercial" grade receptacle. They are only a couple bucks more then the typical residential grade receptacles, but have much better and more durable contacts, and screw terminals for back- or side-wiring rather than the cheap clips.

 

[eprosenx]

Yes, fires can happen, and that's why we use circuit breakers. The only instance I had of a short causing a fire, the circuit breaker turned it off and the fire went out inside the metal outlet box. I agree. Dedicated, 220-240 v circuit on a 50 amp breaker with a 40 amp load. Follow the rules.

My apologies, but I think you are missing the point of the entire video. The failure mode they are simulating was a loose hot wire connection. This causes high resistance which causes heating.

This can happen without ever flowing enough current to trip the breaker. There is no reason for the breaker (or a GFCI for that matter) to trip under these conditions. Hence why this is so dangerous.

In the condition you describe, most likely what happened is that the wires melted enough that the hot came in contact with neutral or ground which did cause enough current flow to blow the breaker.

I would be dead curious to see what voltage looked like at the heater during this test. This is exactly why the Tesla watches voltage and will back off or stop charging if voltage drops too much.

Yes, outlets can be daisy chained, but I don't think that you can do 4 let alone 8.

Garage outlets will generally only be one or two.

But yes loose wire, especially on high current circuits, can burn houses down

Daisy chaining is how pretty much everything is wired these days. There is no limit to it from what I know of NEC. Four or more receptacles is extremely common.

 

[Sophias_dad]

I hate those backstab connectors. I also hate that most of my house is wired with 14 gauge, which at one point was the biggest gauge you could use with backstab, and I think it still is. How much more might it have cost to run 12 gauge and use the screws... 10% of the job cost? 20%? Its priceless to not burn down your house, and have 20 amp circuits that can power a hair dryer AND a bunch of bathroom lights at the same time(before LEDs were a thing).

+1 for checking outlet temperature after charging, I had an older outlet get noticably hot when running a simple vacuum cleaner.

 

[eprosenx]

I hate those backstab connectors. I also hate that most of my house is wired with 14 gauge, which at one point was the biggest gauge you could use with backstab, and I think it still is. How much more might it have cost to run 12 gauge and use the screws... 10% of the job cost? 20%? Its priceless to not burn down your house, and have 20 amp circuits that can power a hair dryer AND a bunch of bathroom lights at the same time(before LEDs were a thing).

+1 for checking outlet temperature after charging, I had an older outlet get noticably hot when running a simple vacuum cleaner.

Cost drives everything in housing construction. A 10% delta cost can mean the difference between winning and losing a bid for a job.

Or say you win the job and if you use the larger wire, that reduces you profit.

FWIW, there is nothing unsafe about 14 gauge wire for 15 amp circuits if installed correctly.

But yeah, I would prefer 20a circuits in my house - I am willing to pay the 10% cost differential, but spec built homebuilders are not. ;-)