Extension Power cord & plug adapter 30A to 20A. Is it a code violation?

J

jesusrperezd

Member
Location
California
Occupation
Engineer
Hi all,

I have a wall-mounted receptacle Nema 6-30R in a 30A circuit (30A breaker and 10awg). In the facility, we have two cord & plug devices. The first one has a plug Nema 6-30P, so we can connect it directly to the receptacle in the wall. The second one has a plug 6-20P. As I understand the NEC, article 406.8 "noninterchangeability" does not allow to connect the 20A plug to the 30A receptacle.

However, a fellow told me that we could use an extension cord adapter if it is built (cable, blades, etc.) to stand the maximum current rating of the circuit (30A); this will be like a short extension cord with two ends, one end will be 6-30P and the other 6-20R. What are your thoughts on that? Below is a link with an adapter like the one described.


is this a code violation? How can this be sold?

Thank you so much!
 
jesusrperezd said:
Hi all,

I have a wall-mounted receptacle Nema 6-30R in a 30A circuit (30A breaker and 10awg). In the facility, we have two cord & plug devices. The first one has a plug Nema 6-30P, so we can connect it directly to the receptacle in the wall. The second one has a plug 6-20P. As I understand the NEC, article 406.8 "noninterchangeability" does not allow to connect the 20A plug to the 30A receptacle.

However, a fellow told me that we could use an extension cord adapter if it is built (cable, blades, etc.) to stand the maximum current rating of the circuit (30A); this will be like a short extension cord with two ends, one end will be 6-30P and the other 6-20R. What are your thoughts on that? Below is a link with an adapter like the one described.


is this a code violation? How can this be sold?

Thank you so much!
Click to expand...
If extension cords had to be able to “stand the maximum current rating of the circuit”, 90% of 120V extensions cords sold wouldn’t meet the requirement.
 
IMHO not legal and the product I doubt is UL listed. The circuit in question is a 30 amp circuit so I doubt you can plug a 20 amp cord into it. its not like a general use receptacle in a house.

And you have to be careful with the "UL" thing.

UL listed is "UL" with a circle drawn around it.

I bought a generator cord on Amazon that had the "UL" on the tag but the "UL" had a triangle around it. The Chinese are very smart.
 
tom baker said:
consider the equipment plugged into that 30A receptacle, its listing likely requires use on a 20 amp branch circuit.
Click to expand...
Really? NEC 422.11(E), or perhaps other subparts of that section depending on what is being plugged in, allows up to a 150% increase in overcurrent protection for an appliance. So if the item being plugged in has a 6-20 plug, it most likely is drawing between 16 to 20 amps. Technically, it needs to have a nameplate of 16.7 amps to be placed on a 30A breaker (less than 16.7 maxxes at a 25A breaker allowance).

I don't see a whole lot of risk in this device. Seems no different to me than an appliance with an 18 AWG cord plugged into a 20A receptacle circuit.

If this cord adapter was premises wiring, it would technically violate the rule of requiring a 20A receptacle to be on a 20A or less circuit. But if the appliance was hard wired, a 30A circuit may be allowable.

What could be a problem is an unprotected power tap (no breaker in it) plugged into that 20A receptacle. That could allow multiple 15 to 20 amp appliances to be plugged into it and melt down the power tap with 30A going through it. But seeing how this is a 6-20 plug (208 or 240V), a 15 or 20 amp power tap for that would be uncommon.
 
You must log in or register to reply here.
Top