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What do you mean by "overcycle"? I have a 14-50 adapter for my oem Bolt evse that I use occasionally on my 240 volt line but mostly I use without the adapter on the 120 volt outlet. I should leave the adapter plugged into the 240 volt and just unplug the evse from the adapter why?
Common 120V receptacles are built with the idea that people will be plugging in and unplugging things all the time, and are built for this use case. A normal 240V receptacle is built with the idea that someone will plug in their stove / water heater / cloths dryer once, and leave it plugged in until it needs to be replaced... not built for repeated plug / unplug cycles.

Keith
 

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I think contributors are getting wound up in receptacle design and reliability in a way that is far beyond common use scenarios and actual specifications.

Is a 120V receptacle designed for 'people will be plugging in and unplugging things all the time'?

Not really.

All receptacles sold in the US need to meet UL specification 498. The common NEMA 5-15R, standard three blade 120V, meets 498. However, there are at least three flavors:

  • Standard Grade: What you buy as the lowest cost item at Home Depot. Still, the receptacle needs to pass 100 connect/disconnect cycles while 150% of the rated current is passing through the receptacle. A reasonable test from UL because connecting and disconnecting a cordset is infrequent in a home environment. That's it. 100 cycles. See [Link].

  • Hospital Grade (UL 498 Supplement SC): Identified by a green dot and simulates frequent make and break connections in a healthcare environment (plug in monitors, pumps, oximieters, etc., and then move to a new patient). These are characterized by additional mechanical and overload testing with testing limited to 150 cycles. Levitton has good pictures of test assemblies; IAEI has details on the tests.

  • Federal Spec WC596: Identified on the box as 'Federal Spec' or by 'FS-UL' or 'FS-CSA' on the metal mounting bracket (bow). Look closely at the left side of the lower mounting ear in the picture below. Tests for the Federal Specification are much more challenging mechanically. Nevertheless, the electrical contact tests do not go beyond 250 cycles, or 2.5x the Standard Grade.


  • Every other grade in the store, such as 'Industrial Grade', 'Commercial Grade', 'Contractor Grade', etc. is a manufacturer's selection of applicable sections of the three UL and Federal Specification grades
So, the run-of-the-mill 120V plug was never tested to be constantly connected and disconnected.

What about a full-on NEMA 14-50R for an oven, or a 10-30R for a water heater?
  • Older receptacles such as the 10-30R may not have Federal Spec compliance to WC496. They will meet UL 498. So--They expect the same number of make-break cycles as the common 120V socket.

  • Newer receptacles like the 14-50R are common in both standard and Federal Specification grades. Again, equal to or better than the common 120V receptacle.
Summary: You cannot assume any socket is designed for more cycles without knowing the applicable standards.

And, as @ArizonaJon noted, there are categories that go way beyond the 120V home plug. Trailer park receptacle assemblies may also meet a more stringent UL Supplement SD, weather resistance. I would add Marine Shore Power receptacles covered by UL Supplement SB. These have special covers and locking mechanisms with unique NEMA locking receptacles. As an example, see the 50A 240V SS2-50R inlet:


If you need to unplug 50A, 240V circuits on a daily basis (every time you leave the dock) with salt water splashing on the receptacle and deck hands often dropping shore cables into the water, get a Supplement SD connector and add it to your EVSE. It's extreme, but it's available.

Creating rituals around receptacles is probably meaningless over the limited periods that people own cars (five years of daily plug ins is only about 1,800 cycles). My feeling is a driver will get bored of dragging out a portable EVSE and plugging it in every day; the driver eventually leaves it connected or gets a permanent L2 well before any mechanical cycle limit for any family of receptacle will ever be reached.

If you are wiring it yourself, it pays to get the best receptacle specifications possible. The price difference is negligible.
 

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I have an adapter that converts NEMA 14-50P to a NEMA 6-20R.

28058


Then another adapter that converts NEMA 6-20P to a NEMA 5-20R.

28059



The OEM EVSE has a NEMA 5-15P. It stays plugged in 24x7. It draws very little power.

:)
 

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I use the OEM EVSE with 110 V and 12 amps most of the time because my utility charges me a demand charge for the maximum hourly power consumption because I have solar panels. (No one else has to pay this.) This was just a way for them to recoup money that they weren't collecting for kWh. I installed a 240 V outlet and a ClipperCreek L2 EVSE before I got the panels, but I now can only use it during a sunny day or I get hit with a high fee. Even then, the utility limits the max power I can install, so I there are only a few hours per day that I can use it without going over. So, during the day, I often use the OEM EVSE in the 240 V outlet with adaptor.
 

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A dash of dielectric grease is probably enough to lube up the blades of a plug. Its not like its a high speed or high pressure metal to metal situation going on there..
 

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