Roof penetration & support

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jap said:
Can we put a C condulet on top of a piece of EMT and then thread the box into the top of the C with a short nipple and get away with it? :angel:


JAP>
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Does it meet the support requirement? Don't forget, the requirement references the conduit entering the box. :D
 
jap said:
Ever tried threading a box on to 2 rigid metallic conduits ?
It's always comical to see the illustrations showing that.:)

JAP>
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NEC doesn't say it has to be practical or easy to change out later, though it is a little surprising since they do like to venture into making themselves a design specification sometimes.
 
jap said:
No it's not impossible just not smart.

I used to take pride in being able to install long runs of rigid without ever having to use unions until one day a very sharp engineer stopped me in the middle of a run and point blank made me install them, especially when approaching a machine or disconnect.

He wanted serviceability in the future and didn't want to "Lock anything into place". Since that day I've been more mindful of things that might need to be removed and add them on purpose.

We had a line of disconnects on a strut stand that were all nippled together with short nipples and Meyers hubs side by side in a row.
He asked, "If the middle disconnect fails,,,, How in the H*** are we supposed to change it out efficiently?".
That was also the first day I started using the Meyers hub that butt up against the outside of the enclosure and have the chase nipple type insert that screws into it from the inside of the enclosure. With a standard hub, you would have not been able to get it out of the middle without loosening all the other disconnects and sliding them apart.

JAP>
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You are obviously assuming that the replacement would be the same manufacturer, part number and dimensions as the original in which case, you could just replace the interior and leave the enclosure as is. But, I do in general respect your integrity in your installations.
 
Jim1959 said:
You are obviously assuming that the replacement would be the same manufacturer, part number and dimensions as the original in which case, you could just replace the interior and leave the enclosure as is. But, I do in general respect your integrity in your installations.
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I'm not assuming that at all.

Unless your talking about something simple like a burnt lug or the like, it's very seldom that I've found replacing the complete interior parts of a disconnect to be more cost effective or quicker than changing the whole thing out.


JAP>
 
Smart $ said:
Conduit body, yes.

Box, no.
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2011 314.23(E) uses the terms "raceway" in the title and the first sentence, and uses the term "conduit" in the third and fourth sentences. I don't believe this change of terminology is an intentional decision to allow EMT in the first sentence and then disallow it in the third and fourth sentences. It's just sloppy language. As conduit is a term that is not defined in the NEC, the word "conduit" in the third and forth sentences should be read as "raceway", the term previously used in that paragraph.

Cheers, Wayne

P.S. On the other hand, 358.12(5) prohibits the use of EMT "for the support of luminaires or other equipment except conduit bodies." So that does prohibit supporting boxes by EMT only.
 
jap said:
I'm not assuming that at all.

Unless your talking about something simple like a burnt lug or the like, it's very seldom that I've found replacing the complete interior parts of a disconnect to be more cost effective or quicker than changing the whole thing out.


JAP>
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In the case of a row of discos nippled together as you described, it varies with the manufacturer of the original equipment installed and the spacing of the installation. Square D discos for instance tend to be tall and narrow, while many other manufacturers discos tend to be wider.
 
wwhitney said:
2011 314.23(E) uses the terms "raceway" in the title and the first sentence, and uses the term "conduit" in the third and fourth sentences. I don't believe this change of terminology is an intentional decision to allow EMT in the first sentence and then disallow it in the third and fourth sentences. It's just sloppy language. As conduit is a term that is not defined in the NEC, the word "conduit" in the third and forth sentences should be read as "raceway", the term previously used in that paragraph.
...
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The use of 'raceway' or 'conduit' doesn't matter because the requirement specifies threaded entries... and RMC and IMC are the only threaded raceway types.
 
Smart $ said:
The use of 'raceway' or 'conduit' doesn't matter because the requirement specifies threaded entries... and RMC and IMC are the only threaded raceway types.
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It seems to me threading an EMT straight connector into a threaded hub would satisfy the 314.23(E) requirements. I understand that there may be other issues with doing that because of the straight/tapered thread issue, and of course 358.12(5) renders 314.23(E) compliance moot.

What about using PVC with a male adapter going into a threaded hub, that would satisfy 314.23(E), right?

Cheers, Wayne
 
wwhitney said:
It seems to me threading an EMT straight connector into a threaded hub would satisfy the 314.23(E) requirements. I understand that there may be other issues with doing that because of the straight/tapered thread issue, and of course 358.12(5) renders 314.23(E) compliance moot.

What about using PVC with a male adapter going into a threaded hub, that would satisfy 314.23(E), right?

Cheers, Wayne
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Fittings do not equal conduit.
It shall be supported by two or more conduits
threaded wrenchtight into the enclosure or hubs.
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Refer to 3xx.1 scopes of each raceway type.
 
So if it's not defined in the NEC, what the heck is conduit anyway?

I'm all ears seeing as how I'm not a big fan of having to use (2) of those threaded things as the sole support for a box anyway and would like to know a code compliant way of getting around it.


JAP>
 
wwhitney said:
Conduit is not a defined term in the NEC, so that is open to different interpretations.

Cheers, Wayne
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A definition is not necessary where there is substantial context.

342.1 Scope. This article covers the use, installation, and
construction specifications for intermediate metal conduit
(IMC) and associated fittings.
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344.1 Scope. This article covers the use, installation, and
construction specifications for rigid metal conduit (RMC)
and associated fittings.
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You can simply look at the Article headings to see which other Chapter 3 wiring methods employ 'conduit'. 3xx.2 Definition will tell you which are threadable.
 
Smart $ said:
Too many and wrong pieces. See attached revised....
View attachment 18540
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I thought the argument was that you couldn't use a fitting and the rigid conduit had to be threaded into the box.

That was my complaint about the rule anyway.

In your drawing the union is in between the rigid conduit and the box, does that satisfy the rule?

JAP>
 
jap said:
I thought the argument was that you couldn't use a fitting and the rigid conduit had to be threaded into the box.

That was my complaint about the rule anyway.

In your drawing the union is in between the rigid conduit and the box, does that satisfy the rule?

JAP>
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Well now that you bring that back into the light, reverse nipple and union. The unions are only there to permit threading/unthreading two conduits into/from two hubs on one box.

Haven't checked out rigid unions lately, but I believe the male thread of a rigid female to male union is NPT, i.e not straight threads. I believe many AHJ would qualify it the same as using a female to female (aka 3-piece coupling) with a close nipple. Po-ta-to, po-tah-to.
 
Smart $ said:
Well now that you bring that back into the light, reverse nipple and union. The unions are only there to permit threading/unthreading two conduits into/from two hubs on one box.

Haven't checked out rigid unions lately, but I believe the male thread of a rigid female to male union is NPT, i.e not straight threads. I believe many AHJ would qualify it the same as using a female to female (aka 3-piece coupling) with a close nipple. Po-ta-to, po-tah-to.
Click to expand...

Post #10 is where the confusion started.

JAP>
 
Smart $ said:
Haven't checked out rigid unions lately, but I believe the male thread of a rigid female to male union is NPT, i.e not straight threads. I believe many AHJ would qualify it the same as using a female to female (aka 3-piece coupling) with a close nipple. Po-ta-to, po-tah-to.
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I thought PVC male adapters use tapered threads, like their plumbing analogs (although I believe I've seen assertions both ways on this forum). In which case the same logic would allow PVC to support a box.

BTW, I'm not convinced by your argument that the threads have to be on a stick of conduit and not a fitting, but I agree it is one reasonable interpretation of the text.

Cheers, Wayne
 
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