using extension cords for charging

I just had another thought... It would be interesting to see a photo of the damage in this case.
There is a possibility that the problem could have been caused / exacerbated by other loads on this circuit.

We have discussed the desire for the EVSE to be connected via a dedicated circuit, but acknowledged that it is not always possible (and can be safe if cautious). I witnessed an event first hand at a relative's house where a receptacle virtually caught on fire. They had an electric heater plugged into a different outlet downstream on the same circuit. There were other loads too, but not enough to trip the 20A circuit breaker. Since residential receptacles are always daisy-chained, it is the earlier receptacles in the chain that experience the highest current (as they pass the current through the chain). In this case, there was likely a poor connection in an early receptacle that overheated and burned (not due to something plugged directly into it, but due to all the downstream current).

@Wdave - Are you aware of any other loads on this circuit? Was the damage clearly done at the interface between the receptacle and your EVSE extension cord, or could it have begun at the rear of the outlet where the wires connect to the receptacle? Were the wires 'plugged' into the holes in the back of the receptacle, or wrapped and tightened under the screws? I agree with others that wrapping under the screws is better. You don't have aluminum wiring do you [very bad for this sort of thing]? It is possible that the extension cord was not the culprit at all.
 
ProspectiveBuyer said:
Is it safe to use a normal extension cord when charging at work if the 120 volt outlet isn't close enough for the cord to reach?
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I made a super heavy duty extension cord to work with my portable level 2 charger. I couldn't find anything less than 150.00 with 8 or 10awg online such as an RV extension cord that would work with my 240 dryer receptacle so I went to the local electrician supply shop and put together a 30 footer with 8awg and heavy duty plugs for only 40.00. This is for my Volt which is charging at 12 amp and there is little to no heat anywhere in the line except at the charger which is Max 105 degrees on the surface, so barely warm. 12 amp is the max that is considered safe for this configuration.
 
KentuckyKen said:
And remember extension cords are not allowed to go through walls, be continuously flexed, or have doors/windows shut on them.
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I removed a lot of information, but I wanted to focus on the bold part.

I have read numerous times that a solution for not having your cable stolen at a public charger is to drive over the cord and leave it under the tire. That freaks me out because of possible damage to the cord.
 
Wdave said:
Directly into the outlet, It's a bit brown so I'm going to replace it this weekend just in case. Although I think 10 gauge wire is overkill, I feel that it just might be better off going with a 12 gauge 25 foot cable and making that work, instead of having a rolled up 50 foot cable on the wall
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Haven't I read posts where they warn against coiling extension cords?
 
Tek_Freek said:
Haven't I read posts where they warn against coiling extension cords?
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You live and learn, I replaced the outlet with a better quality 20 amp one. I have a 25 foot 12 gauge wire snaked along the wall with everything supported and snugly placed.
Haven't had an issue since.
I believe my previous issue was from a bad outlet heating up because of some resistance issue, and melted both the outlet and cord. So I replaced both, made sure that the thing was on its own circuit.
 
You can certainly coil extension cords, but you should do it the right way.
Google for "flip-coiling" or "over-under wrap".

Consumer cords generally have really poor crimped-on ends, which can't
handle continuous high loads. Better to chop those ends off and put
real spec-grade heads on them, assuming the cable itself is decent..

_H*
 
A few people are talking about wire gauge, and while that is of course important, I think it's missing the main point.
The biggest potential failure when using extension cords is due to poor electrical connections at the connectors.
Even a small amount of resistance caused by poor terminal plating, dust/dirt, or insufficient mating can cause a lot of heat dissipation.

A decent EV charger will have thermal sensors in the plug near the blades to protect against this, whereas I guess extension cables won't.

If you really want to go ahead with the extension cable, make sure the blades are kept clean, all plugs are properly inserted, and try to use something with gold-plated terminals.

YB
 
yokobol said:
A few people are talking about wire gauge, and while that is of course important, I think it's missing the main point.
The biggest potential failure when using extension cords is due to poor electrical connections at the connectors.
Even a small amount of resistance caused by poor terminal plating, dust/dirt, or insufficient mating can cause a lot of heat dissipation.

A decent EV charger will have thermal sensors in the plug near the blades to protect against this, whereas I guess extension cables won't.

If you really want to go ahead with the extension cable, make sure the blades are kept clean, all plugs are properly inserted, and try to use something with gold-plated terminals.

YB
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I had to replace both plug ends on a 50’ 12 gauge cord I bought. I replaced the female end first as it was getting warm. A few months later the male started doing the same thing.
The weak point is definitely the plug ends. Get the industrial grade ones for $7-$10 and you’ll be fine. With good plug ends I cannot detect any warmth with my hand.
I don’t know where you could even find gold plugs for normal AC connectors. The heavy duty ones appear to be brass. They are over engineered so you’re fine anyway. the 15 and 20 amp ones appear to share the same conductors. They just have different plastic and the male pins are oriented different.
I guess it’s cheaper to make them on the same line.


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Just as another data point, I used a 25-ft extension cord to charge the Clarity overnight at a friend's place and was a little shaken in the morning to find the cord very warm and the plug end hot to touch. I probably won't do that again (or at least will buy a heavy-duty extension cord for future use).
 
Just a safety reminder.
When choosing and using extension cords, you have to consider more than just the Ampacity of the circuit you are creating by extending the existing circuit. Most people tend to stop at just choosing enough wire gauge to keep the resistance and voltage drop to acceptable levels. However, there are several other important considerations that need to be addressed since “the chain is only as strong as its weakest link.”

As stated above, you must make sure all plug/plug and receptacle/plug connections are tight, clean, and free of even minor corrosion so there is not any added resistance. It makes little sense to properly size your cord and then have a bottleneck at the connection. It’s also dangerous since the heat build up can become great enough to melt the plastic in extreme cases. It’s easy to inspect the prongs and if necessary to clean them up with some fine grit Emory cloth or wire brush. The receptacle is a little harder to see but a dead giveaway is if it’s way to easy to unplug. If it still gets hot or has any signs of heat discoloration, replace it. They’re very inexpensive.

I won’t get into the stab connection vs wrapped around a tightened screw post except to say that I have both in my house (2 different electricians?) and haven’t had any problems. But personally, I would only be happy with stab connections on low draw lighting circuits. Surprisingly enough my ChargePoint has tab pressure loaded terminals and not screw posts.

So now you’re got a properly sized extension cord all your connections are, as our owners of German heritage say, “Gutentite”. How do you keep it that way?

The second thing most people forget is that every extension cord connection is not water tight and that includes the connection to the receptacle. So if your receptacle is outdoors you need a NEMA approved cover that will protect it when not in use AND when anything is plugged into it. Also, you need rain protection at any outside (or floor of a wet garage/carport) plug to plug connection. Not only is this safer, it will make your ext cord and what’s plugged into it last longer. So get some at Walmart, hardware store, or the internet as they are only a few bucks. Or for a little more, some come w gaskets. The receptacle covers are more at around $10-15 or so, and I like the ones that have a deep enough cover to allow plugs without 90 degree ends to make an easy bend and exit the bottom.
You need to do this for your outdoor Christmas lights too.

And finally, as several reminded us above, ext cords are not made to be in constant flex, under tension or compression, or to be used where they are not visible like through a wall or suspended ceiling.
If choosing one for outdoor use, I suggest you get one rated SJTWA which is hard service, thermoplastic, weather approved and that is UL or equivalent listed.
Happy safe charging everyone.
 
Screw connection vs stabbed was answered for me by three separate electricians who worked on our house at different times.

All three will not use the stabbed connections. They each stated basically the same thing: The amount of contact surface is small in a stabbed connection compared to a screw connection and you can control the screw type, but not the stabbed.
 
Had a similar problem with arching/overheating at the wall receptacle recently - loose/dirty plug blade to outlet connections. The screw connections to the circuit were fine. Changed it to a AFCI (arch fault circuit interrupter) receptacle with screw connections. No gold plated connections but it specs claim it will detect arching and cutoff the circuit. It looks like a GFCI outlet with test/reset buttons. Seem to have solved the problem. Will now check the connections and plug blades regularly for signs of dirt and arching and ensure there is a clean solid connection.
 
Rajiv Vaidyanathan said:
Just as another data point, I used a 25-ft extension cord to charge the Clarity overnight at a friend's place and was a little shaken in the morning to find the cord very warm and the plug end hot to touch. I probably won't do that again (or at least will buy a heavy-duty extension cord for future use).
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That’s exactly what was happening to my cord before I replaced the ends


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To commemorate the Christmas spirit, we string up a variety of ornamental lights outside our houses during the holiday season. It is typical to supply these fixtures with power while installing them using an extension cord. if the light is farther than 25 feet from your GFCI outlet, using a heavy-duty 14 gauge power strip is significantly safer. The equivalent 15 amps of the usual residential outlet may be carried by this wire size.
 
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