14-50 extension cords okay?

[GigaToronto]

Mostly human nature. For one thing, if you use it occasionally, you can check it out each time to make sure it's in good shape. If it's plugged in ALL the time, and used every day, you're going to get in the habit of ignoring it, and likely won't notice a problem until you have a failure of some sort. Since the consequences of failure in a high amperage situation can be so dire, it's not worth it in my eyes. Secondly, having extension cords on the floor can be a trip hazard.

From a "giving advice on the internet" POV, a number of people who want to use an extension cord, also want to do things that really are a problem, like running the cord through a wall, or a propped open door, or across a sidewalk, or using a 14-50 adapter with 14-30 outlet.

As far as your situation, if you want to charge outside, then ideally you would install your EVSE outside. I'm not sure why your situation doesn't "allow" that, but you might want to revisit that assumption. Personally, given your choices, I'd bite the bullet and clear room to park my car inside. If it's a truly short term need, I would do an extension cord, although an entire summer seems like a long time. The longest I've done it is for a couple of weeks when construction at my house blocked garage access.

From a convenience standpoint, I will also say that a long, heavy cord (especially the ones that can handle 50a!) can be a pain in the butt to roll and unroll...and you'll have to do that at least enough to get it back inside the garage while you're not using it.

I think a picture might be easier to describe my unique scenerio. I cannot park where the wooden paneling is as it is tight. My driveway is long so I can park further away with the extension. If I move the outlet outside, then it would need to be attached to the panelling and it would not be great for when I am parking inside. Just trying to find the best solutions given the constraints for indoor and outdoor parking. The 14-50 outlet is on the inside of the garage to the left in the picture. Thanks for the input!

As for the EVSE Tesla extension cord, is that any safer as a permanent solution than an 14-50 extension cord?

 

[davewill]

I suppose the EVSE extension at least has the advantage of not being energized except when you're actually charging. It seems like having the outlet just inside the garage door, on the right, would allow you to plug in without an extension cord, whether inside or out. You should even be able to park a decent distance down the driveway if you want. You could install a cable passthrough in the wall next to the door. Am I missing something?

 

[GigaToronto]

The wood panelling is the length of the car about 15.5 ft. I did measure again to mimic if I did move the outlet to the right side of the garage. 4ft up, 2 feet to the garage door and add in another 3 feet up to the car port. I would need to reverse in my car to be about 11 feet away with a 20ft mobile connector. Its not ideal as my kids wont be able to get out of the car without hitting the panelling. I would always have to move the car up to allow them to get in which isnt the end of the world. I will ask an electrician for a quote but labour isnt cheap here in Toronto so I am guessing atleast a $500 job.

 

[davewill]

The wood panelling is the length of the car about 15.5 ft. I did measure again to mimic if I did move the outlet to the right side of the garage. 4ft up, 2 feet to the garage door and add in another 3 feet up to the car port. I would need to reverse in my car to be about 11 feet away with a 20ft mobile connector. Its not ideal as my kids wont be able to get out of the car without hitting the panelling. I would always have to move the car up to allow them to get in which isnt the end of the world. I will ask an electrician for a quote but labour isnt cheap here in Toronto so I am guessing atleast a $500 job.

Might as well also get a quote for putting in a pedestal outside wherever you need it in order to park where you really want to.

 

[Riceball777]

tesla does not recommend extension cords. but i persionally have used a 14-50 extension cord to charge my car and i have never had any issues.

 

[sleepydoc]

A proper cable is very safe. Some are nearly as thick as supercharger cables.

Just wondering what the technical reason why extentions are good for temporary but not long term use. Is it because of increase risk of damage to the cord over time?
If my driveway setup doesnt allow for me to have a wall connector or mobile connector to be within 25 feet of the car, for the summer, is my only option to clear out my garage and park inside or are there any recommended 3rd party chargers that are longer than 25 feet?

The biggest failure point is the connector. with a hardwired connection the screws are properly torqued and secure for long-term use. With an extension cord the contacts in the plug & receptical are prone to physical and environmental damage as well as expansion and contraction with heating and cooling. Over time this can lead to a poor, high resistance connection that can overheat or cause an unacceptable voltage drop.

 

[ambudriver03]

99% of my charging at home is through a parkworld 50 amp rv extension cord (6/4 SJOOW) . (100'). (cost around $400)

My driveway is along a perimeter wall, that at its terminus is the garage mounted weather protected 14-50 outlet (connected to #6 through the garage on a 50a GFCI breaker).

The cable runs along the inside of the block wall (doesn't get stepped or driven across), and when it reaches the end of the wall (near where I park) I have the cable reeled on a wooden rack I made from 2x4s. (I picked wood because it is softer than the SJOOW cable).

Connected to the end of the extension cord is the tesla 40amp corded mobile connector.

So far this has worked well, with the GFCI and the wooden rack (which keeps the cable ends from landing in the drink), it's reasonably safe.

It rarely rains here in Los Angeles as most people know, and if and when it does, I typically will unplug everything at the garage, just in case.

2 years in, the cable is holding up well (it's only in the sun part of the day, and we don't get hard freezes here often)

YMMV.

 

[ambudriver03]

It's 60' from the garage to where I park, and 98' total from the garage to the edge of the street.

With the 100' extension cord, and the 20' that comes with the CMC, I can charge from any spot in my driveway, and the two spaces adjacent to the mouth of the driveway.

(I cannot charge from the house, due to a woefully underpowered subpanel)

 

[jcanoe]

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It's 60' from the garage to where I park, and 98' total from the garage to the edge of the street.

With the 100' extension cord, and the 20' that comes with the CMC, I can charge from any spot in my driveway, and the two spaces adjacent to the mouth of the driveway.

(I cannot charge from the house, due to a woefully underpowered subpanel)

It would be better if you supported the Tesla Mobile Connector chassis instead of letting it hang from the power plug. The power plug adapter is not designed to support this additional weight. You can support the chassis brick with a bracket or even some stiff wire, anything to relieve the strain on the plug.

 

[ambudriver03]

It would be better if you supported the Tesla Mobile Connector chassis instead of letting it hang from the power plug. The power plug adapter is not designed to support this additional weight. You can support the chassis brick with a bracket or even some stiff wire, anything to relieve the strain on the plug.

It is not a mobile connector, I have the corded mobile connector with the hardwired 14-50 plug.

In general, most of the cable is reeled up, and the weight of the 20' never is completely supported by the plug connection alone.

I have a FLIR pro, and regularly check for excessive heat along the extension cord, plug/outlet and CMC.

 

[jcanoe]

It is not a mobile connector, I have the corded mobile connector with the hardwired 14-50 plug.

Same issue though. A power plug (also the receptacle) are not designed to support additional weight. Over time the wiring inside the molded plug can fail. It is why Tesla (also others) sell a Cable Organizer kit that includes a bracket for mounting the electronics brick.

 

[ElectricIAC]

View attachment 819831View attachment 819832

It's 60' from the garage to where I park, and 98' total from the garage to the edge of the street.

With the 100' extension cord, and the 20' that comes with the CMC, I can charge from any spot in my driveway, and the two spaces adjacent to the mouth of the driveway.

(I cannot charge from the house, due to a woefully underpowered subpanel)

Much voltage sag?

 

[ambudriver03]

Much voltage sag?

@ElectricIAC Not bad actually. Considering 28' of #6 Romex (breaker through garage) , 100' of 6/4 SOOW (50a parkworld from the garage exterior mounted outlet) , and then 20' of cable from the tesla EVSE to the car. (148 linear feet, breaker to car)

238 at the breaker, 235-236 at the CMC, sags to 228 at 40 amps, usual charge session averages about 232 according to TeslaFi.

 

[ElectricIAC]

@ElectricIAC Not bad actually. Considering 28' of #6 Romex (breaker through garage) , 100' of 6/4 SOOW (50a parkworld from the garage exterior mounted outlet) , and then 20' of cable from the tesla EVSE to the car. (148 linear feet, breaker to car)

238 at the breaker, 235-236 at the CMC, sags to 228 at 40 amps, usual charge session averages about 232 according to TeslaFi.

And the car doesn’t complain or drop amps?

If our voltage sags below ~233V our chargers wig out and trip the sub-panel. This is with even with us replacing breaker and checking the connections for loose fit.

 

[ambudriver03]

And the car doesn’t complain or drop amps?

If our voltage sags below ~233V our chargers wig out and trip the sub-panel. This is with even with us replacing breaker and checking the connections for loose fit.

When you say it trips the sub panel, you mean that the breaker in the subpanel trips?

In my case, sometimes the CMC throttles down to 32 amps, then slowly crawls back up... If my charging session is less than 1 hour long, the average amps is usually around 36.

I don't know why it does this.

 

[ambudriver03]

I have another 30' (14-50 6/4 SJOOW extension cord which I use when travelling) , I could daisy chain it and see if the CMC acts up...

 

[ElectricIAC]

When you say it trips the sub panel, you mean that the breaker in the subpanel trips?

In my case, sometimes the CMC throttles down to 32 amps, then slowly crawls back up... If my charging session is less than 1 hour long, the average amps is usually around 36.

I don't know why it does this.

Straight up trips the breaker unless the car backs off the amperage beforehand (to 30A on the X) or we lower it manually upon noticing the voltage sag.

 

[ambudriver03]

Straight up trips the breaker unless the car backs off the amperage beforehand (to 30A on the X) or we lower it manually upon noticing the voltage sag.

I added another 60' of cable to the end of my extension, and while the corded mobile connector throttled down, it didn't do it immediately, took 17 minutes to throttle down.

The mobile connector with the 14-50 adapter ran at 32 amps without any throttling, even when the voltage dropped to a low of 224v. (6%)

 

[TripleA]

I have been using a 14-50 extension cord since taking delivery in September 2021 Amazon.com

I had zero issues when charging, getting between 26-28 miles p/h. However since around Feb or March my amps drop from 32 to 16 after about 20 minutes of charging due to excessive heat detection by the mobile connector. This has been an ongoing and frustrating issue. Recently, I noticed a very bad smell from my Mobile connector/xtension cord. Smelled like car brakes after intense usage in a hot day. Since that day, the charger has refused to work or drops the amps much quicker. When I touch the connection to the extension from the MC, it is very hot. I have been leaving the extension outdoors all this time, although I taped around the connection during the rainy season. I believe the extension wire itself is toast. Here is the caveat, the same person to wire my entire connection as also wired it for his own home, using the 14-50 adapter with mobile connector, and his amps drop as well, although he is connceting directly to the outlet and not using an extension cord. This final point confuses me as to what the real error is. I had him check my breaker and outlet after I had the terrible smell, and he states the connection is good with 240v reading.

This is frustrating becasue it seems that when using the 14-50 adapter, there is a common problem with both our setups with losing the amperage, regardless if we are using an extension cord or not.

If anyone would have a legitimate theory on the issue here I would love to hear it. Charging has become a hassle. (FYI I took my MC and 14-50 adapter to a local Tesla service center for troubleshooting, and it had no issues)

 

[jcanoe]

I have been using a 14-50 extension cord since taking delivery in September 2021 Amazon.com

I had zero issues when charging, getting between 26-28 miles p/h. However since around Feb or March my amps drop from 32 to 16 after about 20 minutes of charging due to excessive heat detection by the mobile connector. This has been an ongoing and frustrating issue. Recently, I noticed a very bad smell from my Mobile connector/xtension cord. Smelled like car brakes after intense usage in a hot day. Since that day, the charger has refused to work or drops the amps much quicker. When I touch the connection to the extension from the MC, it is very hot. I have been leaving the extension outdoors all this time, although I taped around the connection during the rainy season. I believe the extension wire itself is toast. Here is the caveat, the same person to wire my entire connection as also wired it for his own home, using the 14-50 adapter with mobile connector, and his amps drop as well, although he is connceting directly to the outlet and not using an extension cord. This final point confuses me as to what the real error is. I had him check my breaker and outlet after I had the terrible smell, and he states the connection is good with 240v reading.

This is frustrating becasue it seems that when using the 14-50 adapter, there is a common problem with both our setups with losing the amperage, regardless if we are using an extension cord or not.

If anyone would have a legitimate theory on the issue here I would love to hear it. Charging has become a hassle. (FYI I took my MC and 14-50 adapter to a local Tesla service center for troubleshooting, and it had no issues)

What brand of 14-50 receptacle is installed? Tesla recommends the Hubbell model 9459a or Bryant model 9450fr 14-50 receptacles. Cooper 5754n is another high quality 14-50 receptacle. The Leviton 14-50 receptacle model 279-S00 receptacle should be avoided for EV charging applications.

Another possible root cause of the amperage being reduced is the temperature of the Mobile Connector 14-50 power plug adapter if exposed to the sun, when charging during daylight hours. Charge after 10PM.