Prevention of undersized circuit with over rated device?
- Thread starter ritelec
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I don't "really" see it.
But I would think maybe Table 210.21 (B)(3) might address it. But it's really addressing receptacles rated less than the circuit, and more than one receptacle.
The example of putting a 30 amp 2 pole receptacle on a 20 amp circ. isn't good practice imo,but, is it.
I had the comment that well "it would trip the breaker" if the 30 amp load was on the 20. I would think there would be an article to address this?
hmmmm
As far as a single receptacle on a circuit is concerned, it appears to me there is nothing that prevents you from using an oversized receptacle. If you had a situation with a lot of use you might want to upsize purely for durabilty.
If does seem that 210.21(B)(3) when there are two or more receptacles or outlets, will not allow a 20 amp receptacle on a 15 amp circuit {Table 210,21(B)(3)}.
That the only restriction of which I am aware.
If does seem that 210.21(B)(3) when there are two or more receptacles or outlets, will not allow a 20 amp receptacle on a 15 amp circuit {Table 210,21(B)(3)}.
That the only restriction of which I am aware.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Have you ever tried to find a NEMA 40A receptacle for a range that calls for a minimum 40A circuit and breaker?
Tapatalk!
Tapatalk!
:- ) Is this a trick question?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
That has been my experience, yes.
Although I have seen a few cases where a 30 is used instead, so as not to overload the breaker.
Tapatalk!
Although I have seen a few cases where a 30 is used instead, so as not to overload the breaker.
Tapatalk!
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- Occupation
- Licensed Electrician
If you overload a circuit you overload a circuit, what difference does it make what kind of plug is on the end of it?
Worse thing would be to have too big of a breaker tied to too small of a plug.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
So what receptacle would one use with a circuit that had a 70,80, or 90 amp overcurrent device? Probably not a 60 amp receptacle. Next higher rated receptacle in most instances would be 100 amps. Where does NEC say a device can not have less load/less overcurrent protection then its rating?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
You just crossed the danger line of common English with that sentence.
Most people hear "less overcurrent protection" and their mind makes the jump to "less protection" therefore not as well protected.
I try to use "lower overcurrent protection" or just lower overcurrent threshold in an attempt to avoid the mental problem, but sometimes it is just too much work and too many words.
Tapatalk!
Most people hear "less overcurrent protection" and their mind makes the jump to "less protection" therefore not as well protected.
I try to use "lower overcurrent protection" or just lower overcurrent threshold in an attempt to avoid the mental problem, but sometimes it is just too much work and too many words.
Tapatalk!
ok ok
Just thinking it didn't sound right.
20 amp brk, 20 amp wire, 30 amp recept.
Not only putting a possible heavier load into that receptacle, which may trip if someone thinks theres a 30 amp circ..
but also, we project or suspect people to do things, which brings this circuit closer to someone saying "just" put a 30 amp breaker on it. It will be ok.
Just saying.
Just thinking it didn't sound right.
20 amp brk, 20 amp wire, 30 amp recept.
Not only putting a possible heavier load into that receptacle, which may trip if someone thinks theres a 30 amp circ..
but also, we project or suspect people to do things, which brings this circuit closer to someone saying "just" put a 30 amp breaker on it. It will be ok.
Just saying.
- Occupation
- Licensed Electrician
The fact is a 30A recpt protected by a 20A breaker is safe. That is all there is to say about it.
Are you willing to be satisfied once you put a stop to this one particular, possible thing an untrained person could do? There will be more you have not seen or thought of yet. Start down this road and there is no end other than a journey into madness.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
How about a 25 amp circuit, 25 amp conductor - can't really use a 20 amp receptacle so you need to go up.
"just put a 30 amp breaker on it" doesn't quite work out though if you have 15 or 20 amp cord caps and want to use a 30 amp receptacle. 15 amp straight blade caps typically will plug into a 20 amp straight blade receptacle, but I am not aware of any 20 amp configuration that will plug into any 30 amp receptacle.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
As Augie has pointed out where you have two or more receptacles on a circuit 210.21(B)(3) says that we must conform to the values in table 210.21(B)(3) which to me seems to say that the receptacle must have a rating of the branch circuit with a 20 amp circuit allowing a 15 or 20 amp receptacle and a 40 amp circuit allowing a 40 or 50 amp receptacles which I think was because of electric ranges with the fact no one makes a 40 amp range receptacle, but it's strange that only the 15 amp states "not over 15 amps, as well as table 210.24 summary stating 15 amp max, but the wording of 210.21(B)(3) could be took as only allowing the size that is listed in table 210.21(B)(3)
I could see where installing a larger receptacle on a smaller sized circuit could also be took as violating 210.23 because it allows a load larger then what 210.23 allows?
I do know that putting a 20 amp receptacle on a 15 amp circuit in an area where appliances that have a 20 amp plug on its cord is a big mistake as home owners will try to use them to the full load current and you will get call backs from tripping breakers, a garage is one such area because of air compressors and small welders, I just don't like installing things that I know will be abused and cause call backs, and of course Joe handyman will fix it by just installing a bigger breaker even though the conductors are only rated for 15 amps, just not a good combination
I could see where installing a larger receptacle on a smaller sized circuit could also be took as violating 210.23 because it allows a load larger then what 210.23 allows?
I do know that putting a 20 amp receptacle on a 15 amp circuit in an area where appliances that have a 20 amp plug on its cord is a big mistake as home owners will try to use them to the full load current and you will get call backs from tripping breakers, a garage is one such area because of air compressors and small welders, I just don't like installing things that I know will be abused and cause call backs, and of course Joe handyman will fix it by just installing a bigger breaker even though the conductors are only rated for 15 amps, just not a good combination
Yes, That's what I do !!!
I was talking about 240v 30amp 3 wire in this scenario with 12's,
But as actiondave mentioned "what possible things an untrained person could do",
serenity !!
OK, I have some company.
Thank you all.
- Location
- Massachusetts
So we must stop putting anymore than one receptacle per branch because that allows people to overload the circuit.
Of course all power strips and three way adapters will also have to be outlawed.
The local inspection departments will run buy back programs to get these dangerous items off the streets.
Of course all power strips and three way adapters will also have to be outlawed.
The local inspection departments will run buy back programs to get these dangerous items off the streets.
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