General Duty Safety Switch not permited?

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iwire

iwire

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A few weeks ago I had to take a CEU course and the two instructors put this question out to us. According to them I got it wrong, so I wonder what you all think.

Can we use a general duty safety switch as the disconnecting means for a HVAC unit located outside a dwelling unit?

If you answer no can you provide a code section?
 
IMO, as long as all conditions of 440.12 are met, you're ok. The listed exemption of 440.12 (a) (1) even mentions a "listed nonfused motor circuit switch". According to that you can.
 
Pierre C Belarge said:
Somehow, I feel like the sheep being led into a valley with steep walls and a bunch of wolves...:D
Click to expand...

:grin:

No I am not trying to set anyone up here, this one perplexed me in the class. They put out an easy question and being the cocky SOB I am I spoke right up and said yes only to be told I was wrong.

They gave me a code section, it is not 110.3(B) but I don't want to give it up yet. I am really interested to find out if anyone else feels the same as the instructors did. I know I was not convinced even though they clearly felt strongly that they where on solid ground. ....... Don't they know who I am? :grin:
 
I am quickly looking at different sites. One of the issues I see, which I never looked too closely at is the fuses used in some of the general duty switches. So far, I see that the fuse types permitted in SQD GDS may limit its usage for HVAC??
 
Pierre C Belarge said:
I am quickly looking at different sites. One of the issues I see, which I never looked too closely at is the fuses used in some of the general duty switches. So far, I see that the fuse types permitted in SQD GDS may limit its usage for HVAC??
Click to expand...

No that was not it.

It is in 110, but I will fess up if this is aggravating anyone, I am not trying to yank anyones chain here. :)
 
iwire said:
A few weeks ago I had to take a CEU course and the two instructors put this question out to us. According to them I got it wrong, so I wonder what you all think.

Can we use a general duty safety switch as the disconnecting means for a HVAC unit located outside a dwelling unit?

If you answer no can you provide a code section?
Click to expand...

Hmm. I looked at both a Sq-D and Murray and I don't see anything that would prevent it. Is it relevant that it was outside a dwelling unit?
 
You did not mention fusible or non fusible. SquareD advertises their safety switches for use on HVAC but I noticed something under the non-fusible I had not noticed prior to your question.

View attachment 3869

(I could not make the print larger, but among other things, it states:
Evaluation of non-fuse switches with molded case circuit breakers has not been performed)

When you read the entire disclaimer, it appears the use of non-fuse general duty switches may be restricted.
 
Bob take a look at the UL book. Switches with horsepower ratings in addition to ampere ratings are suitable for use in motor circuits as well as for general use. Switches with ampere ratings only are intended for general use only. Did they cite 110.3 (B) ?
 
If you really misinterpret 430.109 (e),,,,it could lead you to say not until you get above 100 hp can you use a switch. But again, that would be misinterpreting the article.
 
I believe this has something to do with locked rotor currents in 440.12 - I think... :roll: And that a general duty switch would/may not comply with this requirement - not sure what a dwelling would have to do with it...
 
e57 said:
I believe this has something to do with locked rotor currents in 440.12 - I think... :roll: And that a general duty switch would/may not comply with this requirement - not sure what a dwelling would have to do with it...
Click to expand...

Yeah that article needs a little work ,.. yikes.. I was gonna guess that one too
 
Bob, My memory fails me. Is it possible to open a General Duty switch with the handle in the "On" position, and not do so on Heavy Duty.
I've not tested that theory, but from opening a lot of switches, that may be the case.
Still leads, IMHO, to some interpretive reading for 110.17 but I can see the concern (child factor).
 
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