Do you agree or disagree that 20A receptacles can not be put on a 15A circuit based on Table 210.21(B)(3)?
The circuit is 15A because it has been derated due to too many conductors in a conduit.

15 amp circuits that supply multiple receptacles can not feed 20 amp receptacles.

The text in 210.21(B)(3) seems to be rather clear and points to the Table 210.21(B)(3) and I would say 15a. receptacles on 15a. circuits.

While improper, it is almost certainly harmless. There are very few genuine 20Amp plugs out there. If one were ever to be put on your circuit, it would pop pretty quickly.

BTW, I am shocked that you just didn't pull bigger wire. #12 THHN, above ground, derates to 21Amps with 9 conductors. #10 derates to 20Amps, above ground, with 20 conductors.

If this is a commercial job most customers want a consistent look for their receptacles.

That is not relevant in a forum titled NEC & other Code issues

For what it is worth a 20 amp load on a 15 amp breaker may never open the breaker, it will certainly not open quickly.

Bob

I can't really respond as to the "legal line" of the NEC. Let's look at it another way first.....

A 15 amp circuit, for whatever reasons, is designed to deliver 15 amps (12 continuous).

An appliance with a 20 amp plug has been deemed, for whatever reasons, to require more than what a 15 amp circuit can deliver.

It seems likely, to me, that the appliance will suffer from an inadequate feed. It also seems likely that the appliance will, over time, damage the circuits.

After all, how often do you see wire insulation that has been destroyed, simply because someone insisted on using a too-large light bulb?

Since there are no legal requirements on truth in labeling, it is legal to take an appliance that draws 20amps and place a 15amp plug on it.

My lawnmotor has a 15amp plug and draws 13amps, more than what is allowed on a 15ap circuit. My bandsaw is rated at 1.5hp with the corresponding current draw and a 15amp plug. In reality it is 2hp. Both should have 20amp plugs.

In addition, since a duplex 15amp recept can have 2 15 amp devices (30amps total) plugged in ...

I expect that 20amp recepts on 15amp circuits are not only harmless, but the same effect is common.

But again it is a violation of the NEC unless you hire an engineer and have nhim approve it,

An engineer's approval of a violation does not make the violation go away. It is still a violation. The NEC (310.15(C))does allow an engineer to certify the maximum ampacity of a conductor using the formula printed there. Nowhere, that I can find, does the NEC allow an engineer to certify the use of 20 amp receptacles on a 15 amp circuit.

George


Can you show me where it is a violation have a 13 amp load on a 15 amp circuit?


I have no idea why you would think that, almost all jobs I work on are designed by engineers, they still have to comply with the NEC.



[This message has been edited by iwire (edited 11-08-2005).]

Maybe it takes George over 3 hours to mow his lawn.

I bet that mower is not pulling anything close to 13a unless you are mulching the garden hose.

earlydean ---

I allow the courts to deal with those who disagree with me about code issues.

iwire ---

13amps is simply more than 80% of 15amps and I believe that would require a 20amp circuit. (You can fill in any details of use to make this statement true.)

George, as Scott touched base on, all you would have to do is take a break from mowing every 179 minutes to keep your 15 amp circuit legal.

Roger

When I was learning to use the parachute, we were told the 'chute needed a minimum of 200 ft to work.

Now, I suppose there is someone out there who will claim to jump all the time from 190 ft, and never had a problem. Or 180. Or 170.....

The point is, you can shave the rules all you like, but sooner or later you're going to run out of luck- and go SPLAT!

In another thread (damaged extension cords), the tale is told about a tile saw that didn't work well, at the end of 300 ft of #16 extension cord. Sure, you can put on a smaller pug, use a smaller circuit, and push things to the max- but something will suffer.

Manufacturers aren't entirely stupid. If the product is listed by someone like UL, the rating agency may very well have insisted upon a certain plug. If a product comes with a 20 amp plug, well, that is the manufacturer's way of telling you that the thing needs a 20 amp circuit. @) amp breaker, 20 amp wire, 20 amp receptacle. And, even then, even larger wire may be wise (if the run is long enough).

John, you have hit the nail on the head.

The truth in labeling (or lack of) may come to play in a manufacturer overstating horsepower or performance of a tool, (Tim the Toolman mentality) but if the tool is listed by a NRTL it would come with the proper cord cap to accompany it's listing.

I have a 120v table saw with a 15 amp cord cap that boast a 3hp max output (play on words) that I use on a 20 amp circuit, and we know that a true 3 hp motor wouldn't really work on this circuit.

Roger

I will echo that label "power inflation"
Campbell Hausfelt had to give me an air nibbler (or some other tool from the catalog) because of a class action suit about the labels on their compressors.
Mine says 6.5 HP with a NEMA 5-15 plug.
I did a little informal study of hair dryers a while ago, checking every one I could find with my Fluke clamp on. None pulled more than 12a, in spite of labels up to 1800w.

In the case of this mower, I am sure the 13a is FLA and perhaps a generous cushion. Most of the time a mower runs at a small fraction of full load and we know article 430 lets us use 310.16, not 240.4(D) when we size conductor, so you have to put on your thinking cap and pinch your nose tight when you read 210.23(A)(1)"Cord-and-Plug-Connected Equipment. The rating of any one cord-and-plug-connected utilization equipment shall not exceed 80 percent of the branch-circuit ampere rating."

I have an electric smoker with a 1650w element, a U/L tag and a NEMA 5-15 plug.
From the number of melted 16ga extension cords, damaged receptacles and tripped breakers in it's path before I inherited it, I think that is an accurate label. Go figure.
I know it never caused me a problem on a dedicated 20 with a spec grade receptacle.

[This message has been edited by gfretwell (edited 11-09-2005).]

"I will echo that label "power inflation"

Funny you mention Cambell Hausfeld. I have a particular gripe with my CH compressor too,
5HP with a 5-15 plug and 15 FLA yeah sure 1800W. Even if the motor was 100% efficient it cant be more than 2.4 HP. I guess if I hooked it up to 240V it might hit 5 HP as it burns out.

I should point out that I agree that the NEC disallows 20amp recepts in this case. I simply am trying to say that from an engineering standpoint a 20amp recept is not going to cause any problems that can not be caused using 15amp recepts.

I only have an old code book here. It seems to allow 50amp recepts on 40amp circuits.

Except for the fact that it will be real difficult to get the 20 amp plug in the 15 amp recept.

"I only have an old code book here. It seems to allow 50amp recepts on 40amp circuits."

That is a fairly common setup for electric ranges, at least it is in FL. I see no problem in this case. For instance, I have an arc welder that draws 37 Amps at full range. This precludes the standard 30 amp recepticle, yet it doesnt justify the expense of stepping up to 6 ga and a 50 Amp Ckt. However there I saw no problem running #8 and a 40 amp breaker with a 50 Amp socket.




[This message has been edited by IanR (edited 11-15-2005).]

Just a reminder...there are rules...and then there are the exceptions!

When we wire receptacle for general use, we follow one set of rules. That set, however, has ten 'exceptions,' or special cases where different rules are followed. Two of these exceptions are ranges and welders.

I do not believe there is a need for a specific exception for ranges.

A 50 amp single receptacle can be supplied with a 30 amp branch circuit.

A 100 amp single receptacle can be supplied with a 30 amp branch circuit.

This is the rule for single receptacles.


Bob

[This message has been edited by iwire (edited 11-15-2005).]

renosteinke....

When I was learning to use the parachute, we were told the 'chute needed a minimum of 200 ft to work.

Now, I suppose there is someone out there who will claim to jump all the time from 190 ft, and never had a problem. Or 180. Or 170.....

The point is, you can shave the rules all you like, but sooner or later you're going to run out of luck- and go SPLAT!

Hmmm, skydiving / receptacle ratings, never got the connection before. I think you're right. The reserve might open in 200'-300' but they teach you to have pack opening by 2500'-2000' & make your decision to cut away or ride what you've got by 1800'. All I know is that once you've pulled all your handles, it seems to take 179 minutes for the thing to open.(That & you owe a case of beer.) That 20 amp plug gives them better odds of having their product work properly. That ugly orange & black warning label on the center cell at the tail of my Raven doesn't help me keep from bouncing but it might help the folks that made my chute. That 20 amp plug could save the mfg & cook your keester if something goes wrong.

So if I have to unplug something in an emergency, do I look, grab, protect, pull, punch or look, grab, look, pull, pull?
Joe

This reminds me of the size wire in a light fixture. I know code says ok, but how can you tie in fixture wires usually about 16 gauge to a 15a or 20a circuit?

Because the design of the light fixture will prohibit the conductors being overloaded.

If there is a short circuit or ground fault those short pieces of 16 AWG will still cause the breaker to trip.