Does code require all the pins on a receptacle to be used?

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pipe_bender

Senior Member
Location
Boston
Occupation
Electrician
Stupid question does code require all the pins on a receptacle to be used as marked ?
And if so where in the code is this required?
Assuming I leave a nice printed label on the receptacle stating the voltage would these be a violation:

A pin and sleeve outlet and cord thats 480/3 ph, used it for 480 single phase load (one phase missing)?
A 5 wire 3-phase NEMA L21-30 receptacle to a 208 mixer motor that has no neutral can I leave the neutral pin empty?
A 120/240 NEMA 14-50 with the neutral pin omitted for a 240V EV load.

Thanks all
 
I don't believe there is a specific code prohibition other than possibly ye old 110.3. note there is not even a requirement to conform to the nema standard configurations as long as you don't exceed voltage or current.
 
The only code section that I see is 406.4 you have to have a connection to an equipment grounding conductor and you have to use the identified equipment grounding contacts (pins). I think I remember another one that you can't use the same configuration for two different systems but I cant find it now.
 
tortuga said:
The only code section that I see is 406.4 you have to have a connection to an equipment grounding conductor and you have to use the identified equipment grounding contacts (pins). I think I remember another one that you can't use the same configuration for two different systems but I cant find it now.
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I think it's something like 406.3 f? Basically saying where there are different systems in a building you can't use the same receptacle for different systems
 
electrofelon said:
I think it's something like 406.3 f? Basically saying where there are different systems in a building you can't use the same receptacle for different systems
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Ahh yeah thats it 406.4(F) in my 2023 book, so we have to follow a pattern at any given premises, but the code does not require any particular pattern just that you consistently use one and that ground pins are connected to an equipment ground.
 
Sorry I am still not clear on what the code rules are, I get that is not ideal to install a outlet and omit phase or neutral pin, and in the case of the neutral pin possibly dangerous, I need to cite a clear code section that it violates.
 
pipe_bender said:
Sorry I am still not clear on what the code rules are, I get that is not ideal to install a outlet and omit phase or neutral pin, and in the case of the neutral pin possibly dangerous, I need to cite a clear code section that it violates.
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I don't believe you will find one. Look over 110.3 and see if you think it applies. I think you will find it is arguable whether that applies, and it might depend on how the instructions are worded.
 
My favorite was an L15-30 wired up to jump 5V 30A DC between two racks. Rather spectacular when someone plugged it into 120v instead...
 
IMHO the main code rule being brought up is in NEC 406.4

Receptacles connected to circuits that have different voltages, frequencies, or types of current (ac or dc) on the same premises shall be of such design that the attachment plugs used on these circuits are not interchangeable.

IMHO this should be ready to mean that if you use a receptacle configuration in some fashion, you must use it the same way all over the premises.

If you have an ordinary 14-50 range receptacle wired to 240V, it would be a violation to supply a 14-50 receptacle with 208V in the same premise, even though that configuration is commonly used for either voltage.

As this applies to the original post, IMHO if you only had a single L21-30 on the premises, you could use it without a neutral and be code kosher. But if you had two such receptacles they would have to be configured the same way.
 
winnie said:
Receptacles connected to circuits that have different voltages, frequencies, or types of current (ac or dc) on the same premises shall be of such design that the attachment plugs used on these circuits are not interchangeable.
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Another poorly written and obsolete part of the Code. It should read: "Receptacles designated by NEMA for specific voltages, current or systems shall only be used for those purposes."

Reason being it is widely accepted that NEMA is a standard and accordingly most equipment will have mating plugs for the voltage, current and system it is designed to operate with. There should be an assurance that if a plug fits it will be supplied properly, regardless of if the equipment is manufactured or moved from some other location.

Saying "on the same premises" only gives permission for misuse!

-Hal
 
Here's a scenario to ponder: Let's say you needed 240 volts, 30 amps. Normally you would use a 6-30R receptacle with a matching plug. But maybe you only have a 10-30R on hand. Assume the main panel is where you get your circuit, ground and neutral bar are one in the same. Would it be a violation to use the 10-30 in this manner?
 
hbiss said:
Another poorly written and obsolete part of the Code. It should read: "Receptacles designated by NEMA for specific voltages, current or systems shall only be used for those purposes."

Reason being it is widely accepted that NEMA is a standard and accordingly most equipment will have mating plugs for the voltage, current and system it is designed to operate with. There should be an assurance that if a plug fits it will be supplied properly, regardless of if the equipment is manufactured or moved from some other location.

Saying "on the same premises" only gives permission for misuse!

-Hal
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My only issue with that is there are times when we have a non-standard system and or piece of equipment. For example say we have something that is 400 volt, or something that needs 220V line to neutral? These are both situations I come across. I guess the wording could be such that the configuration as far as line, neutral and ground would have to match but the voltage applied could be lower. So in those cases above for the former you could use a 480 volt and for the latter you could use a 277 volt.
 
CoolWill said:
Here's a scenario to ponder: Let's say you needed 240 volts, 30 amps. Normally you would use a 6-30R receptacle with a matching plug. But maybe you only have a 10-30R on hand. Assume the main panel is where you get your circuit, ground and neutral bar are one in the same. Would it be a violation to use the 10-30 in this manner?
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Yes. For the same reason we can't install it as a 3-wire dryer receptacle.

-Hal
 
electrofelon said:
My only issue with that is there are times when we have a non-standard system and or piece of equipment. For example say we have something that is 400 volt, or something that needs 220V line to neutral? These are both situations I come across. I guess the wording could be such that the configuration as far as line, neutral and ground would have to match but the voltage applied could be lower. So in those cases above for the former you could use a 480 volt and for the latter you could use a 277 volt.
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I agree but require that the receptacle used be the closest available voltage and current configuration and be clearly and permanently marked as to the nonconformity.

-Hal
 
pipe_bender said:
Stupid question does code require all the pins on a receptacle to be used as marked ?
A 120/240 NEMA 14-50 with the neutral pin omitted for a 240V EV load.
Thanks all
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Absolutely not.
But you could try to petition NEMA to create a NEMA 14-50A with a blank spot for the neutral,
and a NEMA 14-50PA with the neutral pin missing.

Or petition NFPA to allow locking connectors to be used for EVSE, in which case you have more choice.
 
hbiss said:
Another poorly written and obsolete part of the Code. It should read: "Receptacles designated by NEMA for specific voltages, current or systems shall only be used for those purposes."

-Hal
Click to expand...

I disagree, because then you are stuck if you are in a situation that doesn't fit the available NEMA patterns.

I agree that it is very good practice to follow NEMA receptacle patterns, and for cases where common appliances are supplied with standard cords then I'd be comfortable with the mandate (120V and 120/240V residential applications, for example).

But once you get to industrial 3 phase stuff you need flexibility to deal with uncommon situations.

Jonathan
 
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