210.21(B)(1) says a single receptacle on an individual branch circuit must have an ampacity not less than the OCPD. A duplex is considered two receptacles so is an exception to this rule. But if you have a 20 amp breaker with one 15 amp duplex, then couldn't there be two loads of 9 amperes in each receptacle? This would not trip breaker but wouldn't 18 amps exceed the 15 amp receptacle rating?
Receptacle rating
- Thread starter cppoly
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes you can have a 15 amp duplex on a 20 amp circuit for the reason you've stated. The duplex receptacle must be designed to allow 20 amps of total current even though each individual receptacle is limited to 15 amps by it's configuration.
- Location
- Massachusetts
To expand on Robs post, the listing requiments for 15 amp duplex receptacals require it be designed for 20 amp circuits.
- Location
- Illinois
- Occupation
- retired electrician
Also the "guts" of 15 and 20 amp receptacles of the same brand and style are identical. The only difference is the slots in the face of the receptacle.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I have heard this and it makes no sense esp. for the cost difference. What a rip off.
- Location
- Massachusetts
If I was making receptacles it would make perfect sense.
Just like how a single receptacle often costs more than a duplex.
A/A Fuel GTX
Senior Member
- Location
- WI & AZ
- Occupation
- Electrician
I think it is basically a supply and demand issue. Single receptacles, 20A receptacles, IG receptacles, etc are not used nearly as often as 15A duplex receptacles and that translates to a higher price.
kwired
Electron manager
- Location
- NE Nebraska
Production comes into play also. If same devices are made on same line, then they probably make the 15 amp devices several days straight and then have to adjust equipment for the one day they decide to make the 20 amp devices.
Look at cost of 4 foot or 8 foot fluorescent lamps, then compare to cost of 2 foot, 3 foot, or even 5,6,7 foot. So much more production and demand of the 4 and 8 even though the others may contain less material is the reason for the price difference.
renosteinke
Senior Member
- Location
- NE Arkansas
You 'know' by delving into the details of the testing at UL.
15/125 receptacles, even single ones, are subjected to exactly the same load / voltage tests as 20/125 receptacles. UL justifies this specifically because the NEC allows 15-A devices on 20-A circuits.
Receptacles are tested with the current 'passing through' them, not with pigtails.
Another quirk of the testing process is that there are plenty of switches approved for use on circuits whose amp rating is far less than the circuit capacity.
15/125 receptacles, even single ones, are subjected to exactly the same load / voltage tests as 20/125 receptacles. UL justifies this specifically because the NEC allows 15-A devices on 20-A circuits.
Receptacles are tested with the current 'passing through' them, not with pigtails.
Another quirk of the testing process is that there are plenty of switches approved for use on circuits whose amp rating is far less than the circuit capacity.
kwired
Electron manager
- Location
- NE Nebraska
Iwire has mentioned it is a listing standard, so they all should be rated for 20 amps feed through but only the individual receptacles are limited to 15, not necessarily because the contacts are only good for 15 but because of the fact it is a 15 amp configuration and a 20 amp cord cap will not physically be able to plug into it.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
It's not an "exception." It is simply a component to which the rule does not apply.
A 15Amp $.69 receptacle's interior guts is not the same as of a 15Amp $2.39 receptacle. However, a 15Amp $2.39 receptacle's internal guts is the same of a 20Amp $3.26.
as you said it is the face plate that makes the difference.
it all depends what you pay for.
Note to OP.
get 3 -4 different receptacles and take them apart and see the difference in quality.
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