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Extension Cord a no no?

44K views 58 replies 36 participants last post by  Ponderling 
#1 ·
I have read that the charge cord for the volt should not be connected to an outlet via an extension cord...

Thoughts from the group?


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#3 ·
Well, not all of us have garages, and if you have an outdoor plug with a rainproof cover, you almost have to use an extension cord due to the very short pigtail at the top of the EVSE.

IMHO, the reason they say that is so that Joe Public doesn't take a flimsy cord they have lying around and try to charge at 12amps. If you have a thick, quality cord plugged into a GFI outlet and protect the connections from the elements, I don't see how it's dangerous. My advice is to build your own cord, since the crimped connectors on store-bought ones are usually the weak link and will fail over time. Home Depot sells power cord by the foot, so you can make it only as long as needed (long cords waste energy and can trap heat if they're coiled up too much, I use 8'). Get weather-rated 12AWG cable and buy quality screw connectors. Check them for heat after construction and once a month thereafter. My EVSE lives in a rubbermaid container, so all connectors are protected from the weather.

I also have a quality 25' cord that I use when I visit friends/family far away (1-2x / year), but it will never pay for itself in gas savings. I almost regret buying it, but it is nice showing new people how it all works and getting a charge if we drive around town. If I'm on a road trip and staying at hotels, I don't even bother trying, it's not worth the hassle to save $2 on gas.
 
#4 ·
Short answer: No. it is generally not safe to do so.

Long answer: Depends. the Volt will be consistently drawing 8A to 12A over the 110V circuit. Even if you use an extension cord with a thick gauge (like 14 gauge for cords less than 25 feet, or 12 gauge for cords between 25 and 50 feet), there are many other factors -- such as the connection between the plug points (which is usually where oxides build up, and cause increased resistance), tripping hazard, risk of getting wet, etc .. which altogether determine if it is safe to use an extension cord.

So, can it be done? Yes .. but it carries a certain degree of risk, and may even be illegal where you live.
 
#5 ·
It is undoubtable safer not use an extension cord. For anything.
That being said, if you are going to it, use a quality cord, 12g or 10g, NOT 14 gauge. Shorter is better. Leave it at the 8 amp setting. Check for discoloration at both ends of cords, and discard if signs of heat damage appear.
We used to do it when all three Volts were here occasionally, but not anymore. One car left for college, and I also added a third L2 charger circuit.
 
#6 · (Edited)
I have read that the charge cord for the volt should not be connected to an outlet via an extension cord...
Thoughts from the group?
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FAQ re 120v charging
http://gm-volt.com/forum/showthread.php?48937-120V-Charging-FAQ

Article 625 of the National Electrical Code (NEC) limits the length of extension cords used with EVSE and permits their use only under certain circumstances. This paper from UL provides some additional info regarding the requirements in Article 625 of the NEC.
http://www.ul.com/global/documents/...sletters/electricalconnections/November10.pdf

The most recent version of Article 625 I found online is from 2008.
http://www.calstart.org/Libraries/E...ents/Article_625_Natl_Electric_Code.sflb.ashx
The most recent version was published in the last year or two and includes lots of changes. I was able to read a copy in the reference section of my library.

KNS

EDIT: Info about the most recent version of Article 625 can be found here
http://ecmweb.com/nec/article-625-electric-vehicle-charging-systems
Free registration is required. I didn't bother.
 
#8 ·
I use an extension cord, but only occasionally. I have found that most of the molded plugs on the ends of ready-made cords are not very good, and will tend to heat up. My 12-2 w/g cord doesn't get warm, but the plug did. So I cut it off and replaced it with a much better plug from Home Depot. Problem solved. So far, the female end of the cord is OK, but I'll probably replace it as well just to be sure.
 
#10 ·
.... My 12-2 w/g cord doesn't get warm, but the plug did. So I cut it off and replaced it with a much better plug from Home Depot. Problem solved. ...
The Volt EVSE would require a 12 gauge - 3 wire cord to work.
I have used an 12-3 cord longer than 25 ft from day one.
12 gauge in the wall. 12 gauge in the cord. What's the difference as long as all the connections are in good conditions?
 
#12 ·
As an EE, I agree with many of the posts here. If your extension need is occasional, get the best 10 gage, 20 A extension you can buy. Invest more and be safe. Keep all plug contacts on both the EVSE and extension polished and clean. All extra connections add resistance points to the electrical path, and each point generates heat and becomes a power loss.

But if you do need an extra long cable with your EVSE all the time, it is safer to replace the original NEMA cord and plug with a longer and heavier cable, and a 15 A or more plug. The cable replacement is a DIY job, but if you don't have the skills or tools, ask a good electrician to do it. Pay up more and get a sale, long lasting extension.
 
#15 ·
I've charged my Volt on a 25' 12 gauge extension cord every night and it's been completely fine. The only outlet in my garage near where my car goes is on the ceiling, so I need an extension cord for the EVSE to be able to be plugged in. The plug gets slightly warm, but not even nearly as warm as a phone charger does while charging, so I'm not worried.

If you need to use an extension cord, don't go over 25 feet 12 gauge or 50 feet 10 gauge and be sure it's a high quality cord that is kept out of the elements when not in use.
 
#17 ·
I've been charging nightly at 12 amps through a 12-foot appliance extension cord for 6 years. My nearest socket is on the garage ceiling, so I needed the extension. It is a supposed heavy-duty cord.

A key reason, rarely cited, that GM discourages use of an extension cord is that the charger's 120V plug has an over-temp sensor that will stop the charging process if the plug or socket gets too hot. That sensor is unable to sense heat at the extension cord's plug end, so suddenly there is an un-monitored plug-and-socket where potentially a fire could start. I occasionally check the temperature at that junction while charging just to make sure it's still staying cool. Never had a problem there.
 
#20 ·
The theoretical reason you are not supposed to is that there is a limit to the allowable distance between the outlet and the GFCI circuitry. If you use an extension cord, that distance is exceeded. This distance is the reason for the very short cord. So you are not supposed to use one.

That said, so long as you use a properly rated extension cord, of course it will work. The electricity came from the power plant, wherever it may be, crossed deserts and mountains or whatever, ran around your city, and through your walls. Do you think it cares if it goes another 25 feet or whatever through an extension cord?
 
#21 ·
Now hold on. Electrons these days aren't the boorish, intolerant electrons of the past. They are more sensitive and caring, more global, and more well-informed (from the approved sources, that is). So I soldered a "safe space" into my appliance cord before installing it. There any electrons that feel they have journeyed too far from the GFCI can stop and rest, realign themselves and relocate their center. Even undocumented electrons (from my solar PV, as opposed to from the grid) are welcome there!
 
#27 · (Edited)
Here's an experiment you should try. Take a bucket of water, put your bare foot into it. Take the EVSE's J1772 plug and drop it into the water - you should be safe because the EVSE needs to negotiate with the vehicle before the power flows. Now dunk the live end of the extension cord into the water....mic drop.
 
#42 ·
While this is true, it's also an argument for never using an extension cord for anything outdoors, because the danger is not specific to EV's. Current NEC code requires that all outdoor outlets be GFCI protected, as well as fitted with a weatherproof in-use cover if it is in a wet or damp location. 240V GFCI breakers are available, incidentally, but not cheap...
 
#29 ·
I've used a quality 12AWG extension cord many times with no issues.

Never would I use or condone the use of an extension cord smaller than 12AWG for charging, but it's worth noting that the G1 Volt stock EVSE used 14AWG wire from the EVSE to the J1772 plug.

If memory serves, I've read of more issues started by poor in house wiring and old receptacles than from the use of extension cords.
 
#31 ·
I use a 12 gauge extension cord at work. It works fine. My 240 volt system I have at home was professionally installed using 12 gauge wire. The electrician told me the 12 gauge extension cord is perfectly safe for a 110 volt outlet. Keep in mind the 110 volt outlet needs to support the current draw of the charger. I just leave it on the 8 amp setting and get about 25 miles on the ticker by the time I get off work. Enough to get home on EV power since I have 7/10 miles still left when I arrive.
 
#32 ·
So, what about those who use 240v with the conversion plug on their stock EVSE? Are there extension cords that would be rated for 240v out there? This could come in useful to me a few times a year when I visit family. They have 50 amp plugs in their garage to use with their RVs. I would not be able to park close enough to reach with the normal length cord. I would need maybe another 20 ft. Bonus points if the cord could also be used on 120v when needed.
 
#37 ·
Almost every cord available in three-conductor is rated for 300 volts. Some are rated for 600. It'll be marked on the cable of good cords, something like "AWG 12/3 STJW" : "W" is okay for outdoor use; "J" means 300 volts, no J is 600; T is "Thermoplastic cladding" and I can't remember what the S is.
 
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