Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

NEMA 16-20 @ 16 amps?

This site may earn commission on affiliate links.
I have a 20 amp NEMA 16-20 outlet relatively near the driveway. From what I can gather, one can order a 16-20 to 15-20 adapter from evseadapters.com ($59 + shipping) and should theoretically be able to pull 16 amps from that outlet, as long as the car is dialed down to that amperage. Anyone with real life experience with this setup?
 
Not able to edit OP for some reason...

Of course I meant 6-20 and 5-20, not 15/16-20 (damn you, autocorrect!)

Also forgot to mention that the EVSE adapter would be used with a NEMA 5-20 Tesla adapter and UMC in this scenario.

So: 6-20R => 6-20P..(EVSE adapter)..5-20R => 5-20 Tesla Adapter => UMC.

Any feedback on pros/cons/risks of this solution as a daily charging setup would be greatly appreciated.
 
Last edited:
You don't need to dial the amperage down. The UMC 5-20 adapter will automatically draw 16A maximum. That's the advantage of this setup using a native UMC adapter. This is a great solution if you already have a 6-20 outlet and don't need to charge faster than about 12 mph.

All yups! :) And it is one of the reasons why I believe all owners should own this versatile/muti-purpose
5-20 UMC adapter. I will also deploy an unmodified 5-20 terminated 50' 12awg extension for 240 or 120v charging that requires no manual amperage adjustment for safe charging if my 50' UMC wont reach.
 
Your UMC is 50' ?! Is that a mod? I thought it came with a 20 foot cable.

All yups! :) And it is one of the reasons why I believe all owners should own this versatile/muti-purpose
5-20 UMC adapter. I will also deploy an unmodified 5-20 terminated 50' 12awg extension for 240 or 120v charging that requires no manual amperage adjustment for safe charging if my 50' UMC wont reach.
 
Last edited:
Another thought, and this may be a bit more risky, why not just wire the 5-20r outlet into the 240v instead of the 6-20r one and cut out the EVSE adapter altogether. I realize it will fry any 120v appliance inadvertently plugged into it, but with lots of labeling it could work! Am I missing something?
 
Another thought, and this may be a bit more risky, why not just wire the 5-20r outlet into the 240v instead of the 6-20r one and cut out the EVSE adapter altogether. I realize it will fry any 120v appliance inadvertently plugged into it, but with lots of labeling it could work! Am I missing something?

Will work, but a very bad/unsafe strategy all around IMO.

Unless you need the extra ~3mph charge rate, I would just deploy the Tesla 6-15 UMC adapter as it will still provide you
with a 1/2 tank ;) overnight without the hassle of using 3rd party adapters that add additional failure points. I have not seen any (not that they don't exist) NEMA 6-20 receptacles that don't accept 6-15 plugs.

These guys "stretched" my UMC to 50' in 2 days.

Tesla UMC extension
 
Last edited:
  • Like
Reactions: Stasla
Will work, but a very bad/unsafe strategy all around IMO.

Unless you need the extra ~3mph charge rate, I would just deploy the Tesla 6-15 UMC adapter as it will still provide you
with a 1/2 tank ;) overnight without the hassle of using 3rd party adapters that add additional failure points. I have not seen any (not that they don't exist) NEMA 6-20 receptacles that don't accept 6-15 plugs.

These guys "stretched" my UMC to 50' in 2 days.

Tesla UMC extension
How does it look when they are done? Are there obvious splices in the cable? Do they extend the existing cable, or replace it in its entirety, giving you a longer, splice-free UMC?
 
I have not seen any (not that they don't exist) NEMA 6-20 receptacles that don't accept 6-15 plugs.
I guess you haven't seen an L6-20 receptacle? ;)
L620R_LL.JPG


I have one of those in my garage in addition to two 14-50 outlets. I don't plan on using it until a third Tesla is parked on the garage. Now that the new HPWC is out which can balance the load, I may end up going that route instead and remove the L6-20.
 
Actually, I am quite familiar with the "L" series (twist-lock line). The OP stated that he/she has a NEMA 6-20 receptacle with no mention of any "L" wiring device.
Ah ok. You had mentioned
the hassle of using 3rd party adapters
so I was thinking you meant any 6-20 receptacle wouldn't require adapters. I guess you were just referring to a regular 6-20 and not the L subset.


It would be nice if Tesla offered a wider range of adapters for the UMC.
 
  • Informative
Reactions: Stasla
Option 1 (safe, recommend)
Purchase the $45 Tesla 6-15 UMC adapter that will charge at 12a@240v and provide ~9mph charge rate on an S (probably 1-2 additional on a ☰)

Option 2 (safe, recommend)
Install an HPWC and set the dip switches for 16/20 amp charging

Option 3 (safe)
Install appropriate EVSE equipment.

Option 4 (not recommended as a long-term solution)
Deploy a custom 6-20P -> 5-20R (BUT wired w/L1+L2 and ground) along with Tesla's 5-20 UMC adapter that will charge at 16a@240v and provide ~12mph charge rate on an S (probably 1-2 additional on a ☰)

Charging from NEMA 6-20 using NEMA 5-20 Adapter

Good-Luck!

btw, for option 1, I would rotate (after de-energizing said branch circuit, of course!) the 6-20 receptacle 90 degrees to relieve the cable/brick strain (for some reason the 6-15 UMC adapter does not align with UMC cable as all the others)
 
Last edited:
How does it look when they are done? Are there obvious splices in the cable? Do they extend the existing cable, or replace it in its entirety, giving you a longer, splice-free UMC?

There are 2 splices. The splices are extremely durable/strong as they are protected by thin ridgid sleeve that is double sealed with adhesive and an outer shrink sleeve for what appears to be stronger than the cable itself attaching points that are waterproof. I have owned this slick professionally assembled fifty-footer for around 2 years and I keep it in the car and deploy a stock length UMC permantly docked on a 14-30 for over 3 years with 80 and 160-mile commutes.
 
Last edited:
I purchased the Tesla 6-20 adaptor and changed one of the plugs in the garage to 6-20. The plug was on a 20 amp breaker and had 12 gage wire, so I should be OK. Even though the car says it's charging at 16 amps on this circuit, I'm getting the same 4 mph charge rate as I did with a 12 amp charge. Using the time to completion, I figure I'm getting a little over 4 mph instead of a little less than 4 mph, but I was expecting better.
 
I purchased the Tesla 6-20 adaptor and changed one of the plugs in the garage to 6-20. The plug was on a 20 amp breaker and had 12 gage wire, so I should be OK. Even though the car says it's charging at 16 amps on this circuit, I'm getting the same 4 mph charge rate as I did with a 12 amp charge. Using the time to completion, I figure I'm getting a little over 4 mph instead of a little less than 4 mph, but I was expecting better.
The mph indicator does not reflect actual values for slow charging unless you've been charging for 8-10 hours, it's just a poor algorithm for the display.

If the car reports 16A, then it is charging faster.
 
Option 1 (safe, recommend)
Purchase the $45 Tesla 6-15 UMC adapter that will charge at 12a@240v and provide ~9mph charge rate on an S (probably 1-2 additional on a ☰)

Option 2 (safe, recommend)
Install an HPWC and set the dip switches for 16/20 amp charging

Option 3 (safe)
Install appropriate EVSE equipment.

Option 4 (not recommended as a long-term solution)
Deploy a custom 6-20P -> 5-20R (BUT wired w/L1+L2 and ground) along with Tesla's 5-20 UMC adapter that will charge at 16a@240v and provide ~12mph charge rate on an S (probably 1-2 additional on a ☰)

Charging from NEMA 6-20 using NEMA 5-20 Adapter

Good-Luck!

btw, for option 1, I would rotate (after de-energizing said branch circuit, of course!) the 6-20 receptacle 90 degrees to relieve the cable/brick strain (for some reason the 6-15 UMC adapter does not align with UMC cable as all the others)

Would the following be an option? Thanks a lot by the way.

NEMA 14-50R to 6-20P Adapter