I don't believe that the KO shown in this thread meets the requirements of 110-12(a). This section requires that the hole closed provide protection substantialy equivalent to the wall of the equipment. Don(resqcapt19)
I don't know if the plug affords "substantially equivalent" protection any more than I know how many wraps of tape are required around a splice to provide insulation "equivalent to that of the conductor", as required by 110-14(b). I don't have a roll in front of me, but isn't the di-electric strength of Scotch33 in the thousands of volts? Does that mean one layer on a 480 volt splice is sufficient? Or, is puncture resistance the issue? How many layers would this require? I dunno! As far as the plug, if the issue is mechanical strength, or to prevent foreign material, I see nothing wrong with the plug shown. If the issue is to contain a fire, it probably provides at least as much protection as most standard panel covers.
If this KO closer was used on any NEMA 1 enclosure, I would say that it is in compliance.
NEMA's definition of a NEMA 1 enclosure states "Type 1 - Enclosures constructed for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment and to provide a degree of protection against falling dirt."
Since the KO closer in question will provide the same protection as the enclosure, the fact that it is thinner is a non-issue, regardless of the wording of the NEC. As thin as this closer is, i don't think I could poke my finger through it.
I've seen just about everyone on these boards, at one time or another, state that they would accept work that did not meet the letter of the NEC, I think this is one of those areas.
[This message has been edited by Tom (edited 08-07-2001).]
Few things are harder to put up with than the annoyance of a good example.
(I removed your duplicate post) If I can toss my 2 cents in here. I too have always thought that it meant "equal to" in size, but upon reading again I can see some different meanings.
Substantial (according to Websters) can mean: "being largely but not wholly that which is specified" When you see the word "substantially" used with "equivalent" it seems like this might be the most likely meaning for the word.
Also, different materials can have different properties which means that they can offer the same protection at different thicknesses.
So, it looks to me like You have to determine what it is protecting from and them make a call from there.