Roof penetration & support

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greenspark1

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New England
Hi all,
I happened to run into both of these yesterday. The situation is roof penetrations with small conduit to a device box and JB. Neither have any support besides the conduit. I thought NEC requires support for both of these installations. I think there are only limited exceptions when using multiple pieces of rigid to a JB (no devices). See attached images #1 & 2. The next part is how the contractor should support these. Thanks for any thoughts!
 

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Are you sure it isn't supported just below the deck line? If not perhaps a piece of Unistrut cantilevered off of the portal for the exhaust fan. I can't see enough of the second one to see a good point for mounting but the same idea would apply.
 
314.23 (E).

Is EMT a 'conduit'? If so then the second one supported by two conduits is okay, provided the conduits have support right under the roof surface less than 18" from the box.

I'm more concerned about the flexible raceways not having any proper kind of support.
 
Thanks for the responses. Unistrut under the roof is a good idea, but sure hard to verify after the install :)
Yes, lacking support on the LFMC is another item. As is the way they penetrated the exhaust fan. It's above the air flow so will get covered in greasy exhaust. It was supposed to go through the shroud 'breather tube' or through the curb.
 
Take a look at sections 314.23 (E) and (F)

The first picture only has the box supported by one raceway - and it looks like it may even be EMT or RMC with compression fitting - needs to be threaded RMC or IMC and needs to be two raceways providing support.

Second picture may be fine - if they used a box with hubs designed for supporting the box - I think it needs to be a type "FS" box and the typical "bell box" like pictured in both images is not listed to be supported by incoming raceways.
 
kwired said:
Take a look at sections 314.23 (E) and (F)

The first picture only has the box supported by one raceway - and it looks like it may even be EMT or RMC with compression fitting - needs to be threaded RMC or IMC and needs to be two raceways providing support.

Second picture may be fine - if they used a box with hubs designed for supporting the box - I think it needs to be a type "FS" box and the typical "bell box" like pictured in both images is not listed to be supported by incoming raceways.
Click to expand...

Ever tried threading a box on to 2 rigid metallic conduits ?
It's always comical to see the illustrations showing that.:)

JAP>
 
jap said:
Ever tried threading a box on to 2 rigid metallic conduits ?
It's always comical to see the illustrations showing that.:)

JAP>
Click to expand...
Meyers hub?
:angel:
Or think like a plumber and have one conduit coming in (rotate the box to attach) and one going out, which you can build starting at the box and dead ending somewhere else.
 
GoldDigger said:
Meyers hub?
:angel:
Or think like a plumber and have one conduit coming in (rotate the box to attach) and one going out, which you can build starting at the box and dead ending somewhere else.
Click to expand...

What's a Meyer's hub going to do for you?

and if you do the in and out thing you will never be able to get the box off the conduits without destroying it and then wont be able to thread one back on them after that so you'd end up with compression connectors anyway.


JAP>
 
Jim1959 said:
Spin both pieces of conduit into the box, support it in place, then go below and connect to the conduits.................
Click to expand...

And as I said before, your left with a box that can't be changed out without taking everything apart and destroying whatever sealing material that was put in place on the roof to begin with without resorting to threadless connectors or compression fittings.

JAP>
 
Just like spinning 2 pieces of rigid into a threaded box to support it above and converting to pvc under the concrete.
Then if or when the box or conduits get damaged its 3 times harder to repair than if it were installed differently.

Having to use rigid 90's and rigid pipes for risers up out of a slab or to support a simple box on a roof is a complete overkill in my opinion.


JAP>
 
jap said:
And as I said before, your left with a box that can't be changed out without taking everything apart and destroying whatever sealing material that was put in place on the roof to begin with without resorting to threadless connectors or compression fittings.

JAP>
Click to expand...

I agree, my post was just a response to a previous post as if it couldn't be done.
Just another way of looking at things, it is in fact not impossible to put it together.
 
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>
 
wwhitney said:
Certainly in the context of (2011) 314.23 (E), since EMT is explicitly listed in the exception as one of the raceways for which a single entry may support a conduit body of a not larger trade size.

Cheers, Wayne
Click to expand...
Conduit body, yes.

Box, no.

:D
 
jaggedben said:
314.23 (E).

Is EMT a 'conduit'? ....
Click to expand...
EMT is a raceway. Been debated as to whether it is a 'conduit'. Technically it is 'tubing'. Regardless, EMT is not threaded, so it cannot be threaded wrenchtight into the enclosure or hubs... no way, shape, or form... as required by 314.23(E) or (F).
 
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