General Duty Safety Switch not permited?

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iwire said:
There must be more than one standard as many discconects have no interlock at all ........ or maybe that is a new standard?
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I just read it again, and it doesn't say what I was sure it said yesterday. It does say that heavy duty switches are required to have an interlock. Yesterday, I thought it said both HD and GD.

You can download and read NEMA KS1 for free via this link:

http://www.nema.org/stds/ks1.cfm

It's a locked PDF, so I couldn't copy and paste the relevant text, and its too long to type.

Its 2.6.4 - mechanical interlock.

Steve
 
So a general duty switch is OK to use for "Service Equipment" (according to the square D catalog, their GD switches can be service entrance rated), but not for an AC disconnect??

We all know that doesn't make much sense.
 
I don't agree with the instructors, but I think their problem was that the hypothetical switch was located outside and not in one of the protected locations mentioned in items (1) through (4) of 110.27(A).

The problem with their logic is that it would require a locked room in a home not accessible by the homeowner in order to allow the use of a general duty switch in a home. Otherwise, this same homeowner that could open the enclosure and get shocked could enter the room and do the same. Items (1) through (3) require the location to exclude unqualified persons (i.e. the homeowner). So, to turn off whatever is disconnected by the general purpose switch, the homeowner would need to call his electrician who has the key :)
 
eprice said:
I don't agree with the instructors, but I think their problem was that the hypothetical switch was located outside and not in one of the protected locations mentioned in items (1) through (4) of 110.27(A).

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Read (past, not present, tense ;)) carefully, items (1) through (4) are alternates to the basic 110.27(A) rule which is "... live parts of electrical equipment operating at 50 volts or more shall be guarded against accidental contact by approved enclosures ..."

Beyond the fact that the switch must be suitable for outdoor use and be horsepower rated, general duty or heavy duty notwithstanding, the class instructors' interpretation was in error.
 
charlie b said:
Thanks for the citation, Bob. Now here is my answer to your instructors:
That is all you need. Might I presume ...
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Beautiful rant in post #39.
We'll just have to agree to agree. :grin:

George Stolz said:
Count me in for a big
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on the 110.27(A) citation. Seems as though I've installed more than a couple AC Disconnects without any guarding over the terminals to speak of, but I wouldn't swear to it. ...
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Guarding over the terminals has nothing to do with accidental contact. That would be finger safe components within an enclosure. The enclosure itself is the guarding against accidental contact.

The instructors also graded you wrong because:
(1) YES << incomplete answer
(2) YES with alternative << complete answer
(3) NO << wrong answer because it implies you can't make it work under the alternatives

But as Charlie pointed out, (1) is both correct and complete. So two strikes against your instructors.
 
rbalex said:
Read (past, not present, tense ;)) carefully, items (1) through (4) are alternates to the basic 110.27(A) rule which is "... live parts of electrical equipment operating at 50 volts or more shall be guarded against accidental contact by approved enclosures ..."
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I agree, that is how the section reads. The instructors referenced in the OP apparently didn't think that the enclosure satisfied the requirement for protection because it could be opened while the switch was in the "on" position. Trying to anticipate what their thought process was, I just wanted to point out that, if you don't think the enclosure adequately protects the homeowner, then you won't be able to use Items (1) through (3) either unless the room in which the switch is located is locked to keep the (unqualified) homeowner out.
 
SEO said:
Sad thing that it's only a wrong answer on an exam but it would be a violation in the field and a re-inspection.
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Yes, and that's what irks me about this. If you perform this installation in this guy's town you will get a violation notice for not actually violating the NEC. :mad: And everybody in the class will come away with a false interpretation of the code and not read the section critically as so many have done in this thread.
 
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