Single 15A receptacle on a 20A breaker

I was recently asked a question by an electrical work planner as to whether you could install a single 15A receptacle on a 20A breaker. From my understanding you can not from Article 210.21(B)1, however you are allowed to install two or more 15A receptacles, and a duplex receptacle counts as two, on a 20A breaker per Articles 210.21(B)3 and 210.24. Just was curious if there is something I might have missed such as some exception I don't know about. Thanks for the responses.
 

infinity

Moderator
Staff member
Location
New Jersey
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Journeyman Electrician
Noting missed you are correct. A single receptacle on an individual branch circuit must be greater or equal to the size of the OCPD. You could put a 20 amp single on a 15 amp circuit.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Noting missed you are correct. A single receptacle on an individual branch circuit must be greater or equal to the size of the OCPD. You could put a 20 amp single on a 15 amp circuit.
You sure?

210.21 Outlet Devices

B) Receptacles

(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
-Hal
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
What is it that doesn't make sense? Plug a 50A load into a circuit protected by a 15A breaker and the breaker trips.
Exactly that! Why does the Code encourage a situation that will insure an overload condition and breaker trip?

You install a 20A dedicated circuit with a 20A single receptacle to supply some piece of equipment that requires 20A. Why on earth would anybody run a 15A circuit to that receptacle?

-Hal
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Exactly that! Why does the Code encourage a situation that will insure an overload condition and breaker trip?

You install a 20A dedicated circuit with a 20A single receptacle to supply some piece of equipment that requires 20A. Why on earth would anybody run a 15A circuit to that receptacle?

-Hal
For example that code sections specifically addresses a 40 amp circuit with a single receptacle, there are no standard 40 amp receptacles so for a 40 amp range circuit you would use a 50 amp receptacle and a 50 amp cord and plug on the appliance.
 

ActionDave

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Durango, CO, 10 h 20 min without traffic from wing
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wire pulling grunt
......You install a 20A dedicated circuit with a 20A single receptacle to supply some piece of equipment that requires 20A. Why on earth would anybody run a 15A circuit to that receptacle?

-Hal
That's a design issue. 210.21 is one of the few places left where the code stays true to its stated purpose of not being a design manual or installation guideline.
 

david luchini

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Staff member
Location
Connecticut
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Engineer
Exactly that! Why does the Code encourage a situation that will insure an overload condition and breaker trip?

You install a 20A dedicated circuit with a 20A single receptacle to supply some piece of equipment that requires 20A. Why on earth would anybody run a 15A circuit to that receptacle?

-Hal
I'll point out the obvious...You wouldn't run a 15A circuit to that receptacle. That would be a violation of 210.19 and/or 210.20.
 

MAC702

Senior Member
Location
Clark County, NV
Elsewhere, in the real world, it is extremely common to put a NEMA 6-50R on a 30A ckt for welding equipment. It's considered the standard plug design even on a machine that draws 18 amps.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
The manufacturer is free to put any plug they choose on their equipment. But if we install a 6-50R it should be on a 40 or 50A breaker. And if an equipment manufacturer puts a 6-50P on their equipment, they need to take the fact into consideration that the receptacle will be on a 40 or 50A circuit.

Point is that we have all kinds of receptacle and plug configurations that reflect the current rating, voltage and number of phases. One purpose of having different configurations is to prevent the connection of equipment to a circuit that it's not intended to operate from. Another is to allow you to see what the voltage/current/number of phases available at that receptacle is by observation. Bad enough this practice isn't always followed but there is no excuse for the code to suggest that you don't need to. Might as well throw the whole system out the window.

-Hal
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I'm missing something. How is this "obvious?" The outlet device is not "the load" so how is this a violation of the actual code?
In his example in post #8 he stated that the equipment "requires" 20 amps so how could you use a 15 amp circuit?
 
So to add some clarification on the issue the end user's piece of equipment comes with a 15A plug installed. Plus, the vendor literature states the power supply should be a 15A dedicated circuit. I did not know this info when I posted the question, but am now providing it. Now I am being told instead of just installing a 15A breaker, the plan is to keep a 20A breaker, remove the 15A plug and install a 20A plug, replace the vendor cord, and install a 20A receptacle. So, in my opinion the plan resolves one issue, but creates additional. Not only does invalidate the UL listing, but the OCPD rating is greater than specified by the vendor. Therefore, the equipment is not properly protected. I will be reviewing the code to see what it states, but would appreciate any comments. If I need to explain anything please let me know. Thanks
 

GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
Elsewhere, in the real world, it is extremely common to put a NEMA 6-50R on a 30A ckt for welding equipment. It's considered the standard plug design even on a machine that draws 18 amps.
It would be common to have a 40 or 50 amp breaker and #10 wire on a WELDING circuit.
 
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