Code violation Article 30amp recpt on 20 amp circuit

Status
Not open for further replies.

electricg

Member
Location
wa
I thought there was an article that prevented this specifically but I cannot find it. Other than common sense and not wanting to mislead the end user, is it a violation to put a 30amp 250 volt receptacle on a 20amp ciruit/breaker? the wire is sized #10 copper is what I am told, so that should not be an issue.

210 tells the maximum, but the I do not see where you are prevented from do this.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I know of nothing that would disallow such a practice.
In the past I have seen folks use 50 amp outlets on much smaller circuits when there is serious repeated use and they wanted the "beef" of the heavy receptacle.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
I think the only issue is placing a lower rated receptacle on a higher rated circuit like placing a 20 amp Rec on a 50amp circuit.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Here is my take: If this receptacle is the only outlet on the circuit, then 210.21(B)(1) explicitly allows it. If there is anything else on the same circuit, then 210.21(B)(3) and its associated table explicitly forbids it.
 

electricg

Member
Location
wa
Here is my take: If this receptacle is the only outlet on the circuit, then 210.21(B)(1) explicitly allows it. If there is anything else on the same circuit, then 210.21(B)(3) and its associated table explicitly forbids it.

I agree with the 210.21(B)(1) 3 interpetation, however i think it is being a little libral with 210.21(B)(1). I think 406.8 Noninterchangeability may apply here.

"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......"

Key word is intended. One has to check with UL to see what the intended reason was.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
A single receptacle can be rated higher than the ampacity of an individual branch circuit. One example is 40 amp range circuits with 50 amp single receptacles.
 

electricalist

Senior Member
Location
dallas tx
Im not knowledgeable on all the diff receptacles. I would look at the needs of the equipment then the cord. If its a 30 amp circuit from the panel to the equipment except for the breaker,,maybe its a derated circuit or voltage drop or existing circuit and the equipment was changed out requiring 20 amps.
Since i dont know im curious as to what equipment needs 30 amp outlet but a 20 amp circuit?
 

darekelec

Senior Member
Location
nyc
I installed 20 amp 220V circuit with 30 amp receptacle for Miele speed oven recently.
 

Attachments

  • miele.jpg
    miele.jpg
    22.5 KB · Views: 5

mbrooke

Batteries Included
Location
United States
Occupation
Technician
I installed 20 amp 220V circuit with 30 amp receptacle for Miele speed oven recently.


I bet they require that just because the assume it to be the most common. I know Euro dryers with no noodle and only needing 15 amps call for a 30amp 14-30r.

My understanding is that nothing in the NEC disallows a single 20amp outlet on a 15 amp circuit or a 50amp receptacle on a 40amp breaker.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Nothing disallows a dozen 50A receptacles on a single 14 AWG 15A circuit if the circuit is for a single roving load.

Edit: sorry, the exception is for a welder only, I forgot it was more specific.
 

electricg

Member
Location
wa
Ok. So the only violation would be when the someone plugs in equipment that needs a 30amp branch circuit and its only a 20amp branch circuit. Even though they were mislead to believe it was a 30amp circuit because it was a 30amp receptacle that is configured to take only 30amp plugs/cord caps.
 
Ok. So the only violation would be when the someone plugs in equipment that needs a 30amp branch circuit and its only a 20amp branch circuit. Even though they were mislead to believe it was a 30amp circuit because it was a 30amp receptacle that is configured to take only 30amp plugs/cord caps.

I can't see that as a code violation. Breaker might trip, but that's its purpose :D.
 

GerryB

Senior Member
Ok. So the only violation would be when the someone plugs in equipment that needs a 30amp branch circuit and its only a 20amp branch circuit. Even though they were mislead to believe it was a 30amp circuit because it was a 30amp receptacle that is configured to take only 30amp plugs/cord caps.
I guess I'll ask the obvious. You said as far as you know the wire is #10, so why wouldn't you put it on a 30a breaker? Single pole or double pole, whatever it is? Same price.
 

electricg

Member
Location
wa
I guess I'll ask the obvious. You said as far as you know the wire is #10, so why wouldn't you put it on a 30a breaker? Single pole or double pole, whatever it is? Same price.

The reason there is #10 wire on a 20amp breaker is because of derating the ampacity of the wire. There are at least 9 ccc conductors in there. In another pipe from the same panel there is over 10 ccc, and this is just counting the hots, not the neutrals.

I am aware some guys do not derate their wires ampacity, but that does not make it right either. All these circuits are running at the same time. There will need to be a #8 if they want to upsize to a 30amp breaker, or other wise just leave the 20amp breaker.

I will accept that it is legal to put a 30amp receptacle on a 20amp breaker. Its just not prudent to do it in all cases. ;-)
 

electricalist

Senior Member
Location
dallas tx
If there are 9 hots and 3 neutrals in the first conduit then it has 9 ccc..Which wouldnt change the wire size because the percent value derated is still good for #12 awg,,,
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
I thought there was an article that prevented this specifically but I cannot find it. Other than common sense and not wanting to mislead the end user, is it a violation to put a 30amp 250 volt receptacle on a 20amp ciruit/breaker? the wire is sized #10 copper is what I am told, so that should not be an issue.

210 tells the maximum, but the I do not see where you are prevented from do this.
Common sense, while narrowly defined and understood by the user of the term at the time he or she uses it, is actually very broad and ill defined.

Common sense tells me that 20A circuit breaker doesn't know what kind of receptacle it has hooked onto it. Common sense tells me a 20A circuit breaker is supposed to do its job.

Common sense tells me anything that can go wrong.........wait that's a law.... Hey! HEY!!! Oye! You Murphy!! Stop messing with my definition of Common Sense! Go on now, move along.
 

iwire

Moderator
Staff member
Location
Massachusetts
Ok. So the only violation would be when the someone plugs in equipment that needs a 30amp branch circuit and its only a 20amp branch circuit.

Isn't that that pretty much the same violation that can happen anytime someone plugs into a multi-receptacle outlet circuit?

Even though they were mislead to believe it was a 30amp circuit because it was a 30amp receptacle that is configured to take only 30amp plugs/cord caps.

No one was mislead, there is nothing in the NEC that tells us a 30 amp receptacle has 30 amps of capacity at anytime. It could be on smaller breaker or the circuit might already have loads on it.



I would like you to consider the following.

You are hired to wire a portable industrial machine, it must be cord and plug connected.

The machine has a minimum circuit size of 65 amps and a maximum overcurrent protection listing of 70 amps.

What size receptacle and cord cap are you going to use?
 
Status
Not open for further replies.
Top