Duplex outlet current rating

[lshaff01]

Hi. I've been told that a 15 amp duplex outlet is identical to a 20 amp duplex outlet except for the face plate. If that is true, what is the max current rating for a 15 amp duplex outlet ? Thanks.

 

[Little Bill]

20A if there is more than one receptacle on the circuit.

 

[infinity]

Hi. I've been told that a 15 amp duplex outlet is identical to a 20 amp duplex outlet except for the face plate. If that is true, what is the max current rating for a 15 amp duplex outlet ? Thanks.

Even if the entire metal interior of the receptacles were not the same the only part that would need to be the same is the metal tab that ties the two binding screws together. Having said that everyone seems to agree that the metal parts of the 15 and 20 amp devices are the same.

 

[Jerramundi]

Even if the entire metal interior of the receptacles were not the same the only part that would need to be the same is the metal tab that ties the two binding screws together. Having said that everyone seems to agree that the metal parts of the 15 and 20 amp devices are the same.

Is this true for the actual capacity of the interior components of the receptacle?

I always thought it was 20A feed through, which I thought I recalled seeing on some spec sheets in the past, but can't seem to find on any more recent spec sheets.

In regards to multiple 15A general purpose receptacles being on a 20A general purpose branch circuit,
I always understood it to mean that the receptacle could be wired in a series fashion with the rest of the circuit (i.e. how some guys land the line side of the circuit on one set of terminals and load side of the circuit on the other set of terminals, which I hate and want to clarify that I always, always, always, pigtail from a splice to the receptacle itself) and the terminals themselves + the metal tab that ties the two terminals together could handle 20A, say if it were part of a 20A circuit that featured multiple 15A receptacles downstream with a load totaling 20A.

It's my understanding that the NEMA configuration limits the receptacle to 15A and that no appliance cable that could feed a 20A load could match up with that NEMA configuration. Hence the difference between the 15A configuration and the 20A configuration. Therefore the only explanation of the receptacles ability to conduct 20A would be for the situation outlined above and it begs the question of whether or not the interior components could actually handle 20A.

 

[infinity]

I always thought it was 20A feed through, which I thought I recalled seeing on some spec sheets in the past, but can't seem to find on any more recent spec sheets

The theory is that it's cheaper for the manufacturer to keep the internal parts of 15 and 20 amp receptacles the same and just use different configuration faces.

 

[Jerramundi]

The theory is that it's cheaper for the manufacturer to keep the internal parts of 15 and 20 amp receptacles the same and just use different configuration faces.

Do you recall the 20A feed through specification that I'm talking about though? I distinctly recall it on past spec sheets, but can't seem to find it on any more recent ones.

 

[hbiss]

Is this true for the actual capacity of the interior components of the receptacle?

Did you read this from infinity? "Even if the entire metal interior of the receptacles were not the same the only part that would need to be the same is the metal tab that ties the two binding screws together."

And probably the reason that spec you saw isn't there any more is because the NEC specifically allows 15A duplex receptacles on a 20A circuit. What more needs to be said? They make their receptacles to comply with that Article.

-Hal

 

[Jerramundi]

Did you read this from infinity? "Even if the entire metal interior of the receptacles were not the same the only part that would need to be the same is the metal tab that ties the two binding screws together."

Dude, relax. Of course I did. It's just a question and a discussion... and a valid one at that because apparently a "retired electrical engineer" doesn't even know the answer here... and one whose profile is no longer on the forum??

 

[infinity]

Dude, relax. Of course I did. It's just a question and a discussion... and a valid one at that because apparently a "retired electrical engineer" doesn't even know the answer here... and one whose profile is no longer on the forum??

The simple fact that a 15 amp duplex receptacle is permitted on a 20 amp circuit would indicate that the feed through portion of the device must be rated for 20 amps otherwise the NEC would not allow it on a 20 amp circuit.

 

[Jerramundi]

The simple fact that a 15 amp duplex receptacle is permitted on a 20 amp circuit would indicate that the feed through portion of the device must be rated for 20 amps otherwise the NEC would not allow it on a 20 amp circuit.

Which is exactly what I was saying in my comment about the receptacle being wired in a series fashion, but questioning whether or not the internal components of each individual receptacle on the duplex could handle 20A, to which my understand is no.

 

[infinity]

but questioning whether or not the internal components of each individual receptacle on the duplex could handle 20A, to which my understand is no.

The obvious answer is yes the fed through is rated for 20 amps.

 

[Jerramundi]

The obvious answer is yes the fed through is rated for 20 amps.

The feed through portion being rated for 20A is not the same thing as each individual receptacle on the duplex, yoke being rated for 20A, unless I'm misunderstanding what "feed through" is, which is why I asked about it.

Again, going back to my original post, I was under the impression that each individual receptacle was rated for 15A, but the entire duplex had a 20A feed through rating (see previous explanation of it being wired in series on a 20A circuit with multiple other 15A receptacles downstream).

If the 20A feed through is referring to the individual components of an individual receptacle on a duplex, then there's no need to even rate it as a 15A receptacle in the first place, just call it a 20A receptacle. The logical conclusion being that are different ratings on the one device. The 15A portion and the 20A feed through portion.

The only other logical conclusion is that the industry is playing games and selling an unnecessary variety of components and I don't think we to turn over that rock because something tells me we won't like what's underneath, lol.

 

[hbiss]

then there's no need to even rate it as a 15A receptacle in the first place, just call it a 20A receptacle.

A 15A 5-15R receptacle will only accept a 5-15P 15A plug. It will not accept a 20A plug (5-20P). However, the 20A 5-20R receptacle will accept both a 5-15 plug and a 5-20 plug. Those are the ones with the T slot.

This is why there are 15 and 20 A receptacles. Rarely would you ever need to use a 20A receptacle in residential since nothing would have a 20A plug but you see them all the time because the installers mistakenly believe that a 20A circuit requires a 20A receptacle. Except for a single receptacle on a 20A circuit that is not the case.

-Hal

 

[ActionDave]

If the 20A feed through is referring to the individual components of an individual receptacle on a duplex, then there's no need to even rate it as a 15A receptacle in the first place, just call it a 20A receptacle.

Or call it rated for 20A feed through.

The logical conclusion being that are different ratings on the one device. The 15A portion and the 20A feed through portion.

The whole device is rated at 20A, not specific portions of it.

The only other logical conclusion is that the industry is playing games and selling an unnecessary variety of components and I don't think we to turn over that rock because something tells me we won't like what's underneath, lol.

Provided they are of equal quality the only difference between a 15A and 20A recpt is the shape of the slots in the plastic face. It's been that way longer than I've been alive and probably longer than you and I combined have been alive.

 

[LarryFine]

Hi. I've been told that a 15 amp duplex outlet is identical to a 20 amp duplex outlet except for the face plate. If that is true, what is the max current rating for a 15 amp duplex outlet ? Thanks.

Yes, for almost all grades, and 20a; some are probably 30a.. Note that either a horizontal or vertical blade will have three points of contact:

 

[Little Bill]

@Jerramundi
Have you seen this?

Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits
Circuit Rating
(Amperes)
15 - 15A receptacle rating
20 - 15A or 20A receptacle rating
30 - 30A receptacle rating
40 - 40A or 50A receptacle rating
50 - 50A receptacle rating

 

[tortuga]

I have seen a properly terminated 15A duplex turn into melted gue after having a 1500W resistive heater load plugged and running on it for just a few years. I'd hardly trust a 15 or 20A rated duplex to supply much more that that. Feed thru screws on a 20A circuit no problem, back stab feed thru for a 15A circuit YMMV.

 

[Fred B]

I have seen a properly terminated 15A duplex turn into melted gue after having a 1500W resistive heater load plugged and running on it for just a few years. I'd hardly trust a 15 or 20A rated duplex to supply much more that that. Feed thru screws on a 20A circuit no problem, back stab feed thru for a 15A circuit YMMV.

Seen the weakened spring slot terminal cause excessive heating and melting down the receptacle. Usually a result of user error of removing a plug off to the side and stretching that spring metal of the receptacle terminal over time. Also the continued use of the obviously weak connection of the receptacle or a high load such as mentioned. Haven't seen one that had proper terminations and wasn't abused that melted down on a load within the parameters of the circuit amperage.
Cheap receptacle might have a weaker although correctly sized metallic components from what I've seen. Thus I would never recommend using the cheapest receptacles you might find at a dollar store or in the 50 cent bin. There are some receptacles locations in a residence that you can expected multiple plug and unplug cycles in a day and these would suggest using a higher quality receptacle as you can more readily get the effect mentioned with the cheap ones.

Never backstab.

 

[Frank DuVal]

Seen the weakened spring slot terminal cause excessive heating and melting down the receptacle. Usually a result of user error of removing a plug off to the side and stretching that spring metal of the receptacle terminal over time.

And let's not forget all those cord yankers....

I've seen a lot of plug overheating, which also overheats the receptacle, from people yanking the cord to unplug the device. Grip the plug and remove straight out. Easy.

 

[ggunn]

Which is exactly what I was saying in my comment about the receptacle being wired in a series fashion, but questioning whether or not the internal components of each individual receptacle on the duplex could handle 20A, to which my understand is no.

Nothing in household receptacle wiring is in series; everything is in parallel. Even if you jumper from one receptacle to the next the receptacles themselves are in parallel.