15 Amp devices in a 20 Amp circuit

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kbsparky

Senior Member
Location
Delmarva, USA
Re: 15 Amp devices in a 20 Amp circuit

...Where is the language in the NEC that allows the fusible disconnect..
I believe that 240.21(B) allows for a 60 Amp fusible switch to be supplied by a 100 Amp feeder.

...Or more to the point where is the section in the NEC that tells us that a receptacle must be supplied within it's current rating at all?
I would refer you to 110.3(A)(7) as well as 110.3(B) for that.
 

izak

Senior Member
Location
Springfield, MO
Re: 15 Amp devices in a 20 Amp circuit

i agree wholeheartedly with the man with the lance chasing the windmills... or beating the horse that is not dead yet... this sounds like a horse i would beat myself...

the listing doesnt SAY the device is 'Rated for 15A Load, or 20A feed-thru'.
its a black and white matter... the paper is white, and the letters are black... most of the time...
if you cant find IT in black and white, then you cannot say what it is...
 

coulter

Senior Member
Re: 15 Amp devices in a 20 Amp circuit

Originally posted by kbsparky:
... can you provide me with some tangible reference that backs up the claim that 15 Amp duplex outlets can be installed as part of the circuit conductors on a 20 Amp circuit? ...
Try UL 498. Its all about receptacles and testing for compliance.

The UL test for both 15A and 20A is to overload test at 150% followed by a feed-through temperature test, followed by a retention test. The overload portion is different, 22.5A test current for the 15A recpt and 30A for the 20A recpt. The feed-through test amps are the same, 20A.


carl
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: 15 Amp devices in a 20 Amp circuit

Thanks for getting back to me on my questions.
:)

Originally posted by kbsparky:
...Where is the language in the NEC that allows the fusible disconnect..
I believe that 240.21(B) allows for a 60 Amp fusible switch to be supplied by a 100 Amp feeder.
You are obviously a guy that cares a lot about the specific wording of code sections. That being the case you will have to agree that 240.21(B) only applies to conductors, not the switch.


Originally posted by kbsparky:
Or more to the point where is the section in the NEC that tells us that a receptacle must be supplied within it's current rating at all?
I would refer you to 110.3(A)(7) as well as 110.3(B) for that.
Again if these sections mean what you say they mean the fusible disconnect is also in violation if supplied above it's rating.

I do hope UL gets back to Don, my view is obvious.

UL and the NEC work hand in hand and if this was an issue there already would be a code section similar to this one.

300.13 (B) Device Removal. In multiwire branch circuits, the continuity of a grounded conductor shall not depend on device connections such as lampholders, receptacles, and so forth, where the removal of such devices would interrupt the continuity.
I just don't buy the notion that the NEC and UL have overlooked this issue (if there is one) for this many years. :)

Bob

[ November 29, 2005, 04:40 AM: Message edited by: iwire ]
 

pierre

Senior Member
Re: 15 Amp devices in a 20 Amp circuit

If I am understanding this correctly, I agree with Bob. 240.21(B) deals with the protection of TAP conductors, not the equipment that this type of conductor supplies. Reading the definition of tap conductor may help in the understanding of this issue.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: 15 Amp devices in a 20 Amp circuit

Don,

Thanks for your inquiry. Sorry for the delay in responding.

UL 498, the Standard for Attachment Plugs and Receptacles, has requirements regarding receptacle feed-through terminals. For receptacles rated 15 or 20 A, 125 or 250 V, the feed-through construction is evaluated using a test current of 20 A and is considered suitable for use in a 20 A branch circuit. For further clarity, we will consider adding this information to our directory guide information.

Please contact me if you have any further questions.

Rich

Rich Berman
Sr. Staff Engineer
Regulatory Services
Underwriters Laboratories
333 Pfingsten Road
Northbrook, IL 60062
 

kbsparky

Senior Member
Location
Delmarva, USA
Re: 15 Amp devices in a 20 Amp circuit

Don:

Finally, some documentation regarding this issue. Thank you.

As to my original posting of this subject, I now would have to disagree with the inspector flunking the installation, since UL 498 recognizes a 15 Amp receptacle as capable of sustaining the current flow of a 20 Amp circuit.

Thanks for your posting in the EKF as well :)
 
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