60-amp receptacle on 40-amp circuit and less

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Jps1006

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I have a piece of equipment 250-volt 3-phase fed from an SOOW 8/4 drop cord with a waterproof pin and sleeve connector rated at 60-amp fed from a circuit on a 40-amp breaker.
Next to it is another machine with an identical setup, except it's fed from a 30-amp breaker.
Next to it is another machine with an identical setup except it's fed from SOOW 10/4 on a 20-amp breaker (all 60-amp pin and sleeve connectors).
Code violation?

(NEC 2011) 210.20 (b)(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.

What am I missing?
 
Jps1006 said:
I have a piece of equipment 250-volt 3-phase fed from an SOOW 8/4 drop cord with a waterproof pin and sleeve connector rated at 60-amp fed from a circuit on a 40-amp breaker.
Next to it is another machine with an identical setup, except it's fed from a 30-amp breaker.
Next to it is another machine with an identical setup except it's fed from SOOW 10/4 on a 20-amp breaker (all 60-amp pin and sleeve connectors).
Code violation?

(NEC 2011) 210.20 (b)(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.

What am I missing?
Click to expand...

I'm not sure what you are missing. You just described three circuits where the receptacle has an ampere rating not less than that of the branch circuit, per 210.21(b)(1).
 
Seems like it should be a code violation from a practical point of view. Am I missing some other part of the code that would forbid this? I have always matched receptacle ratings to circuit ratings, so I was surprised to see this allowed. Anyone could unplug the the larger machine and plug it into the 20-amp circuit and overload it.
 
Jps1006 said:
Seems like it should be a code violation from a practical point of view. Am I missing some other part of the code that would forbid this? I have always matched receptacle ratings to circuit ratings, so I was surprised to see this allowed. Anyone could unplug the the larger machine and plug it into the 20-amp circuit and overload it.
Click to expand...

Then the breaker would trip.
 
406.8 Noninterchangeability. Receptacles, cord connectors,
and attachment plugs shall be constructed such that receptacle
or cord connectors do not accept an attachment plug with a different
voltage or current rating from that for which the device is
intended. However, a 20-ampere T-slot receptacle or cord connector
shall be permitted to accept a 15-ampere attachment plug
of the same voltage rating. Non–grounding-type receptacles and
connectors shall not accept grounding-type attachment plugs.
Click to expand...

My understanding is all those 60 Amp pin and sleeve configurations are the same.
and the setup described is a 40, 30 and 20 amp setup all using the same configuration.
 
tortuga said:
My understanding is all those 60 Amp pin and sleeve configurations are the same.
and the setup described is a 40, 30 and 20 amp setup all using the same configuration.
Click to expand...

A 60A plug will plug into a 60A receptacle.

A violation of 406.8 would be a 40A receptacle that would accept a 60A plug.
 
david luchini said:
A 60A plug will plug into a 60A receptacle.

A violation of 406.8 would be a 40A receptacle that would accept a 60A plug.
Click to expand...
Good point,
you don't think the code is saying the rating of the branch circuit modifies the rating of the receptacle?
 
It just seems wrong. So I could change all the 15-amp outlets on 15-amp circuit in my house out to 20-amp devices and not have violated the code?
 
Jps1006 said:
It just seems wrong. So I could change all the 15-amp outlets on 15-amp circuit in my house out to 20-amp devices and not have violated the code?
Click to expand...

No, you couldn't. The only 15A receptacles on 15A circuits that you could change to 20A receptacles would be single 15A receptacles on individual branch circuits.
 
Last edited:
This is very common in the welding machine world. Most machines are equipped with a NEMA 6-50P plug. The machine might only need 30A of 240, and if this was your only machine, and you made a circuit dedicated for it, you could make a 30A branch circuit with a 50A receptacle on #10 Cu, and that doesn't even factor in that you could use smaller wire on a welding machine, too, because of its duty cycle.
 
david luchini said:
No, I don't.
Click to expand...
I like how you make me think and I see your point. Occasionally I see old 50 Amp crows foot receptacles (NEMA 10-50 I think) on 30 and 40 amp dryer circuits, with 10AWG copper and a 30A breaker, in your opinion this is not a violation because Table
210.21(B)(3) only applies if we have two or more receptacles or outlets.

However it could be argued the 'rating' 406.8 is talking about is the NEC rating of the individual branch circuit as determined by by 210.18.
By way of definition of a branch circuit:
Branch Circuit. The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).
Click to expand...
the receptacle is included.
and
210.1 scope covers branch circuits.
and the rating is:
210.18 Rating. Branch circuits recognized by this article shall
be rated in accordance with the maximum permitted ampere rating or setting of the overcurrent device...
Click to expand...
 
tortuga said:
I like how you make me think and I see your point.
Click to expand...

I believe in short and to the point

tortuga said:
Occasionally I see old 50 Amp crows foot receptacles (NEMA 10-50 I think) on 30 and 40 amp dryer circuits, with 10AWG copper and a 30A breaker, in your opinion this is not a violation because Table
210.21(B)(3) only applies if we have two or more receptacles or outlets.
Click to expand...

That is correct. 210.21(B)(1) allows a single 50A receptacle on a 30A individual branch circuit.

tortuga said:
However it could be argued the 'rating' 406.8 is talking about is the NEC rating of the individual branch circuit as determined by by 210.18.
By way of definition of a branch circuit:
Click to expand...

I don't see how that could be argued, as 406.8 doesn't say anything about branch circuit ratings. It says receptacles and connectors shall not accept a plug with a different voltage or current configuration. In the OP's case, the receptacle and plug have the same voltage and current configuration...there is no violation of 406.8.

tortuga said:
the receptacle is included.
and
210.1 scope covers branch circuits.
and the rating is:
Click to expand...

The receptacle is not included in the definition of branch circuit, only the circuit conductors. I'm not sure where you are getting at with 210.18, as we have already established that a single receptacle on an individual branch circuit is permitted to be larger than the branch circuit rating.
 
On a few occasions over the years I have installed "oversized" receptacles where equipment is plugged in repeatedly causing failure of the "standard size" receptacle from the constant plug-unplug actions. IMHO, prohibiting such action would actually increase the "danger" as the smaller receptacles often have significant arcing and physical damage as compared to the
"oversized" one.
 
augie47 said:
On a few occasions over the years I have installed "oversized" receptacles where equipment is plugged in repeatedly causing failure of the "standard size" receptacle from the constant plug-unplug actions. IMHO, prohibiting such action would actually increase the "danger" as the smaller receptacles often have significant arcing and physical damage as compared to the
"oversized" one.
Click to expand...

Well I learned something new on here again. I just checked my dryer plug and it is in fact a old NEMA 10-50 which is pretty common to see, on the nameplate of the dryer it says "connect to a 30A individual branch circuit, with minimum 10AWG copper conductors". So the 40A OCPD is the only violation in my case ;)IMG_20190313_152511.jpg
 
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