NEMA 5-15p to 5-20r adapter trip report

[eprosenx]

So first off I have to state that this is not code compliant, not UL rated, and could be dangerous.

I have this adapter which allows me to use the Tesla 5-20 adapter on a 5-15 receptacle. This allows me to crank the charge current up to a max of 16 amps.

https://www.amazon.com/gp/aw/d/B017EUTHC0

So while I would never recommend this adapter for use on a regular basis, it has a limited use case if you are willing to assume the risk.

This weekend I was at a friends vacation home which has a spare dedicated 20a 120v circuit for a refrigerator that only serves this single quadplex receptacle a few feet from the panel. I had previously verified this was backed by 12 gauge wire. I also thermally imaged it during charging and it did not heat up at all.

While I generally argue against solutions like this, it certainly made a difference for me this weekend as I drove several hours to Bend from Portland for the weekend and then back. Having this available helped me get to a full state of charge before the return trip (I also stopped at a supercharger in Bend, but being able to charge at the house like this covered all my local trips for the weekend).

Insert note here about how this defeats the thermal monitoring built into the UMC Gen 2 plug ends...

I thought others might find this info useful in the future.

 

[F14Scott]

Vinny Gambini:
I object to this witness being called at this time. We've been given no prior notice he'd testify. No discovery of any tests he's conducted or reports he's prepared. And as the court is aware, the defense is entitled to advance notice of any witness who will testify, particularly those who will give scientific evidence, so that we may properly prepare for cross-examination, as well as give the defense an opportunity to have the witness's reports reviewed by a defense expert, who might then be in a position to contradict the veracity of his conclusions.

Judge Chamberlain Haller:
Mr. Gambini?

Vinny Gambini:
Yes sir?

Judge Chamberlain Haller:
Mr. Gambini, that is a lucid, well thought-out, intelligent objection.

Vinny Gambini:
Thank you.

Judge Chamberlain Haller:
Overruled.

I wouldn't do it, myself. The insurance company would roast you, no pun intended. The words "deliberately overloaded" come to mind.

However, if the breaker is 20A, the outlet is the only one on the circuit, and the wire is properly sized, why not just swap in a new 5-20 outlet? Then you're legal.

 

[P85_DA]

However, if the breaker is 20A, the outlet is the only one on the circuit, and the wire is properly sized, why not just swap in a new 5-20 outlet?

Because it’s his friends house

 

[iluvmacs]

Because it’s his friends house

"Hey friend, do you mind if I buy you a $5 receptacle and replace this one you have, so I can charge safely?"
"Nah, please keep using the setup that's a fire hazard."

 

[ewoodrick]

Yes, the extra 1 mph makes a huge difference.
And the possibility of tripping a breaker is huge.

The only redeeming thing here is quad plug, which should be wired for 20a. Not all plugs are

 

[SigNC]

Yes, the extra 1 mph makes a huge difference.

While I don't condone this adapter the difference between 5-15 and 5-20 charging is quite significant.

 

[brkaus]

Help - someone hacked into @eprosenx account and posted this thread!

 

[SWUtah]

Since the OP (eposenx) has already stated that he's verified that the circuit is rated for 20 amps (12 Ga wire, 20A breaker, & the outlet is the only one on the circuit), what's all the flap about? I use this identical scenario when charging at my brother-in-law's house. 16A vs 12A is the difference between 6 mph and 4 mph on my Model 3. The thing to be aware of is that this 'cheater' plug could get you in trouble if you use it on a normal 15 A household circuit (14 ga wire, 15A breaker).

 

[iluvmacs]

Since the OP (eposenx) has already stated that he's verified that the circuit is rated for 20 amps (12 Ga wire, 20A breaker, & the outlet is the only one on the circuit), what's all the flap about? I use this identical scenario when charging at my brother-in-law's house. 16A vs 12A is the difference between 6 mph and 4 mph on my Model 3. The thing to be aware of is that this 'cheater' plug could get you in trouble if you use it on a normal 15 A household circuit (14 ga wire, 15A breaker).

Technically, the receptacle itself is only rated for 15A. The system is only as strong as the weakest link.

(Now before anyone tries to get me on this other technicality: yes, often the actual receptacle guts are the fabricated identically for 5-15 and 5-20 receptacles, and they just put a different front plate & label on it -- but we don't know that in this case, and it's still kind of abusing the system... if you caused a fire and insurance took a forensic look at it, they will point at this and win).

 

[mswlogo]

Help - someone hacked into @eprosenx account and posted this thread!

I agree. Should we report it?

The clear headed, common sense @eprosenx would have put in the correct outlet for his friend. Even if the outlet itself is the only weak link here it’s not designed for that load. Probably “jet wired” to boot.

 

[eprosenx]

Vinny Gambini:However, if the breaker is 20A, the outlet is the only one on the circuit, and the wire is properly sized, why not just swap in a new 5-20 outlet? Then you're legal.

Yeah, this is a really good point. The reason I have not pursued upgrading this receptacle to a 5-20 is because my real intent is to get something much better installed (like a hard wired EVSE or at least a dedicated 14-50). It is only a matter of time before someone in the family that owns the house gets an EV, so I figured they would drive that getting done. ;-)

Even if I can't get a 14-50 in the near term, I was thinking of swapping this receptacle to a 6-20, but it is complicated by the fact that all the faceplates in the house are black (not as commonly stocked), it is in a smaller city so I need to order my parts ahead of time, and the owner has a plug in hybrid with a puny 5-15 EVSE that they use on this specific circuit. So if I upgraded this circuit to 240 then we would need to get the owner a 240v EVSE so they could continue using it (but it would help out their BMW X5 charging speed as well!). Also, if I go to a 6-20 I am not sure what the heck to do for a face plate. I would need a single round faceplate plus a blanking panel or something for the other side. All in black... So that is more challenging to source.

And the possibility of tripping a breaker is huge.

The only redeeming thing here is quad plug, which should be wired for 20a. Not all plugs are

So there is zero danger of tripping the breaker in this situation. The danger is that you are using a receptacle which is only rated at 15a but you are drawing 16a continuous through it.

In the US it is fully legal (and exceedingly common) to put 15a receptacles on a 20a circuit. In fact, in residential you are hard pressed to ever find a 20a receptacle. I am not aware of any requirement for quad jacks like that to be 20a.

Technically, the receptacle itself is only rated for 15A. The system is only as strong as the weakest link.

(Now before anyone tries to get me on this other technicality: yes, often the actual receptacle guts are the fabricated identically for 5-15 and 5-20 receptacles, and they just put a different front plate & label on it -- but we don't know that in this case, and it's still kind of abusing the system... if you caused a fire and insurance took a forensic look at it, they will point at this and win).

Yeah, totally correct. Though while the receptacle itself is only rated for 15a, it does have to be rated to pass through 20a of current on the daisy chain connections on the back. So we are really only talking about the suitability of the prongs to be able to transfer that amount of current.

And to add more context to @iluvmacs comment, here is a photo of a tear down of *one* manufacturers 5-15 and 5-20 receptacles. Note that internally they are identical (but one has the horizontal slot covered over). Now this does NOT mean all manufacturers do it this way and obviously they are not rated this way...

I shamelessly stole this picture from the following thread (so credit to them):
5-15R vs. 5-20R - Specifically, What's the DIfference? - Page 2

So yes, overall, I would file this in the category of "neat hack", but it is not a substitute for proper wiring. I probably should not have even shared it. ;-)

 

[wws]

With "spec" - commercial quality - receptacles, it seems 5-15 and 5-20 are pretty much identically constructed internally. Where I would seriously question this is if cheapo $0.39 'residential' quality receptacles are used. But I would recommend replacing residential quality with commercial quality even when charging at 12 amps continuous. (Also I'd guess you made certain that the screw terminals were being used when wiring the receptacles, and not the 'push-in holes'.)

 

[eprosenx]

With "spec" - commercial quality - receptacles, it seems 5-15 and 5-20 are pretty much identically constructed internally. Where I would seriously question this is if cheapo $0.39 'residential' quality receptacles are used. But I would recommend replacing residential quality with commercial quality even when charging at 12 amps continuous. (Also I'd guess you made certain that the screw terminals were being used when wiring the receptacles, and not the 'push-in holes'.)

Yeah, I checked how they were wired. They are actually not only under the screw terminals, but also pigtail wired so they don’t jump from one duplex receptacle to the other, they are “split” in with a wire nut.

Admittedly, I did not check the brand of receptacle, but it is a custom built home and the electrical work is done fantastic quality. Nothing was done “cheap” in this house. But yeah, good points!

I just ordered an industrial rated 6-15 and 6-20 receptacle to keep “in stock” for future situations (white though).

 

[mswlogo]

Yeah, I checked how they were wired. They are actually not only under the screw terminals, but also pigtail wired so they don’t jump from one duplex receptacle to the other, they are “split” in with a wire nut.

Admittedly, I did not check the brand of receptacle, but it is a custom built home and the electrical work is done fantastic quality. Nothing was done “cheap” in this house. But yeah, good points!

I just ordered an industrial rated 6-15 and 6-20 receptacle to keep “in stock” for future situations (white though).

Decora, Standard, Ivory, White and Brown? Oh and Almond.

 

[gfunkdave]

Here's a 2 gang cover with only a single outlet opening.

https://www.amazon.com/Bryant-Electric-NP147W-Receptacle-Wallplate/dp/B003A5B63M

 

[wws]

Admittedly, I did not check the brand of receptacle, but it is a custom built home and the electrical work is done fantastic quality. Nothing was done “cheap” in this house. But yeah, good points!

If you compare something like a Leviton BR-15 or BR-20 (or Decora equivalent) to its 'residential' brethren (e.g., the '10 pack for $3.99' specials), the difference in construction is immediately apparent. One has a nice steel backing plate running from top to bottom and feels 'heavy'. Nice clamping of the wires, the wipes hold the plug blades firmly in place. The other ... feels like it will twist around every time you plug something into it, and eventually may break. Ok for a table lamp in a living room, but not what one wants for EV charging.