warning: plugging/unplugging a UMC daily

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MelindaV

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#1
came across this on Reddit of a condo owner who has an outdoor 14-50 outlet and plugs his UMC into it every 2-3 days over the last two years.
tl:dr the outlet he was using was not designed for repetitive plugging and unplugging and wear caused the prongs to no longer making solid contact inside the outlet, causing excess heat at the bad connection.
If you are planning something similar, make sure you are installing a receptacle intended to have daily use and not a typical appliance outlet that is rarely unplugged, and replace if the socket begins to feel loose when plugging into it.

 

JWardell

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#4
I saw this on Reddit, too. It was simply caused by extreme heat due to a bad or loose connection in the plug or socket. It could be very dirty prongs, or a very loose wire connection inside the socket. No part of the charger or cable failed here, and it's easy to repair/replace.
I really doubt that it was due to the socket not being designed for repetitive connection. It's no different, and better off, than any other socket. It's very likely that the prong was dirty or corroded.
This does illustrate an issue I often seen with regular plugs at home, though. Home depot usually has "value" and "premium" options on the shelf for each kind of outlet. The premium versions have much beefier contacts in the sockets as well as higher general build quality. The budget sockets will have problems like this within a few years of use. Go for the premium when you have the option.
 

RandyS

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#5
My two cents worth....

* For a better connection, orient the receptacle so the plug and cable to the UMC point down (not sticking up and then looping down)
* Install some sort of strain relief for the UMC brick so it doesn't put weight on the connection and start to pull it out of the receptacle
* Inspect the connections, cords, plugs, etc. occasionally to make sure everything is okay
* Think about getting a HPWC (Which doesn't have these connection problems) and leave the UMC in the trunk for occasional use...
 

SoFlaModel3

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#6
My two cents worth....

* For a better connection, orient the receptacle so the plug and cable to the UMC point down (not sticking up and then looping down)
* Install some sort of strain relief for the UMC brick so it doesn't put weight on the connection and start to pull it out of the receptacle
* Inspect the connections, cords, plugs, etc. occasionally to make sure everything is okay
* Think about getting a HPWC (Which doesn't have these connection problems) and leave the UMC in the trunk for occasional use...
I am comfortable with electrical work, but certainly no electrician. I have always scratched my head at why my dryer plugs in upside down. I certainly will make note of that when I get one installed in my garage... unless of course I get the Tesla wall charger.
 

17.088

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#9
this is the correct orientation with the pin on the top
Sorry to be nit-picky, but technically NO, the correct word is not "correct", it is "most relevant".
The National Electrical Code (US-primarily, I know) does not specify which direction the ground prong must face.

It's true that buildings East of the Appalachian mountains and Hospitals tend to have the ground up, but otherwise most of the U.S. tends to have the ground on the bottom side.

In other words, do what is most relevant to your load's needs, whether that be a dryer plug or an EVSE plug.

17.088 ^2
 

SoFlaModel3

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#10
Sorry to be nit-picky, but technically NO, the correct word is not "correct", it is "most relevant".
The National Electrical Code (US-primarily, I know) does not specify which direction the ground prong must face.

It's true that buildings East of the Appalachian mountains and Hospitals tend to have the ground up, but otherwise most of the U.S. tends to have the ground on the bottom side.

In other words, do what is most relevant to your load's needs, whether that be a dryer plug or an EVSE plug.

17.088 ^2
Tesla suggests ground up for the Nema 14-50.
 

17.088

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#11
And for a very good reason.
Look at how their cord is manufactured; gravity is pulling down on the cord in such a way that the if the ground had been on the bottom, a lot of stress would be on the connection.
The ground terminal on the top, given the design of their plug, makes the most sense.

It's a classic situation of doing what makes sense as opposed to doing whatever you want to do.
Or put another way, pay attention to the application, and let that drive your installation.
In this case, having the ground up IS the most relevant thing to do.
But STRICTLY speaking it's neither correct nor incorrect, just relevant.

Yea, yea, a nitpick, I know.
 

RunCycle

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#12
I have a couple questions about outside charging.
  1. Is it better to keep the Mobile Charger plugged into the NEMA 14-50 socket all the time outside or to unplug it each time you charge?
  2. Would it be better to install a Tesla Wall Charger outside instead of the NEMA 14-50?
 

SoFlaModel3

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#13
I have a couple questions about outside charging.
  1. Is it better to keep the Mobile Charger plugged into the NEMA 14-50 socket all the time outside or to unplug it each time you charge?
  2. Would it be better to install a Tesla Wall Charger outside instead of the NEMA 14-50?
Technically speaking, I believe the UMC is rated for outdoor use so you should be fine. That said, if my setup was outside I probably would get the HPWC. It would feel safer to me and also not have the worry of someone stealing my UMC as I wouldn’t want to unplug/re-plug for every charge.
 

M3OC Rules

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#14
I have a couple questions about outside charging.
  1. Is it better to keep the Mobile Charger plugged into the NEMA 14-50 socket all the time outside or to unplug it each time you charge?
  2. Would it be better to install a Tesla Wall Charger outside instead of the NEMA 14-50?
Not sure if this is going to happen but I was told Tesla is going to stop recommending NEMA 14-50 because of issues with some GFI breakers. California may not require GFI but you probably should have it for an outdoor outlet. You don't need GFI breakers if its hardwired, ie wall connector. With the Wall Connector you also don't have to worry about wearing out the socket by regular plugging or someone stealing your $300 cable. The Wall Connector can also provide faster charging if wired for it, can be daisy chained to allow multiple Wall Connectors to share one circuit, and provides diagnostics if something is wrong with the wiring. Also it looks cool and integrates a wall hanger for the cable. Only downsides are you can't plug in anything else there and cost.
 

oey192

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#15
I have talked to two different Tesla employees in a showroom (once in Jul 2017, once in Jan 2018) and both times they recommended the 14-50 plug with UMC over a HPWC. I ignored their advice and am having a HPWC installed when my solar system goes up (next week!) because I don’t want to have to worry about the UMC getting warm when plugged into the wall but not the car and because I think I will want to daisy chain a second HPWC on the same circuit in a few years when the Model Y comes out and my house gets its second Tesla…
My electric panel also has enough capacity for the HPWC to get 60A so I can charge my LR (AWD) Model 3 at its max speed for the very rare cases I will need to do so.

My setup is indoors but outdoors I would definitely get an HPWC over a 14-50 outlet even without the other considerations above.

Also, since AWD is still a ways off I got a UMC to J1772 adapter so I can charge my Leaf with the HPWC until my Model 3 arrives (right now I trickle charge the Leaf). This somewhat negates the downside of not being able to plug anything else into the 14-50 outlet, especially since the pre-2018 Leaf EVSE doesn’t work with a 14-50 outlet out of the box.
 

RunCycle

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#16
Thanks for your replies. We are thinking of getting a padlock and locking the Mobile Connector cord to the house or fence or something even though it won't be visible from the street when not in use.
 

Vin

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#17
I was curious as to the thickness/diameter of the HWPC vs. the UMC cables because I'm getting a cable cover (similar to what they use for outdoor concerts) to protect the cable across a sidewalk when plugged in (once or twice a week).
Does anyone who owns both notice a big difference or is it basically minor?

Thanks.
 
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theishu

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#20
I was curious as to the thickness/diameter of the HWPC vs. the UMC cables because I'm getting a cable cover (similar to what they use for outdoor concerts) to protect the cable across a sidewalk when plugged in (once or twice a week).
Does anyone who owns both notice a big difference or is it basically minor?

Thanks.
Ditto!