Conduit Support

[StronerRich]

I work for a large manufacturing company, and have been discussing the following with my state electrical inspectors, supporting IMC or Rigid conduit drops. On our industrial machines located on the shop floor in areas where there is no means of intermediate support we follow Article 342.30(B)(3) or 344.30(B)(3) which states that vertical risers that are less than 20 feet in length and are supported and securely fastened at the top and the bottom do not need any other means of support. Our vertical conduit runs are supported at the top and we contend that when the conduit enters into a panel (such as a large Hoffman electrical panel) and secured with the proper locknuts the top of the panel becomes the support for that conduit run. After a recent electrical inspection, our state inspectors feel that we have to come up with some sort of additional supporting means for the bottom of the conduit run, hence the discussion. I have worked in the industrial electrical field since the 1970's, have a Master Electrical license, and I have never added additional support to any vertical conduit drops that are installed like this. Also this practice has never been questioned before. Any thoughts? Thanks

 

[GoldDigger]

What is supporting the panels?
I.e. are these fixed to the floor in some way or attached to skid-mounted machinery?
Is the inspector for some reason concerned about what will happen if the panel is removed or moved?
Tapatalk...

 

[jdixon]

344.30 requires both A and B and A requires support within 3ft of box or cabinet.

 

[don_resqcapt19]

I have have seen supports built at the bottom end for that application. The inspector is correct based on the code rules. There is nothing in any of the "rigid" raceway articles that even suggests that the conduit termination can be used as the securing or supporting method.

 

[StronerRich]

StronerRich

StronerRich

What is supporting the panels?
I.e. are these fixed to the floor in some way or attached to skid-mounted machinery?
Is the inspector for some reason concerned about what will happen if the panel is removed or moved?
Tapatalk...

No these are either large hoffman style panels 72 high x 12 deep x 48 wide or they are 30 to 60 amp fusible safety swtches mounted to a rigid frame work. In either case they are anchored to the concrete floor. Rich Stroner

 

[StronerRich]

StronerRich

StronerRich

344.30 requires both A and B and A requires support within 3ft of box or cabinet.

If you look at 344.30.B.3 which states vertical risers from industrial machinery where there is no other means of intermediate support, the conduit (as long as it has threaded couplings) can have up to 20 ft. between supports. This is what I have, the inspectors are not questioning the vertical riser support at the ceiling, they are just saying that it must have support at the bottom. The conduit runs into a large machine control panel or a fusible disconnect. Both of which are mounted securely to the concrete floor. Rich Stroner

 

[StronerRich]

StronerRich

StronerRich

I have have seen supports built at the bottom end for that application. The inspector is correct based on the code rules. There is nothing in any of the "rigid" raceway articles that even suggests that the conduit termination can be used as the securing or supporting method.

I would agree with you that there is nothing that says that the large equipment panel or fusible disconnect can be considered as support for the bottom of this conduit run. But since this question has come up I have asked my electrical suppliers and they have never heard of such a rule and also they say if it was, someone out there would be making some sort of support fixture to mount on the backs of these panels. Rich Stroner

 

[pjholguin]

Is it possible to extend uni-strut from the support frame? Two vertical extension cross-connected to a horizontal member.

PJHolguin

I would agree with you that there is nothing that says that the large equipment panel or fusible disconnect can be considered as support for the bottom of this conduit run. But since this question has come up I have asked my electrical suppliers and they have never heard of such a rule and also they say if it was, someone out there would be making some sort of support fixture to mount on the backs of these panels. Rich Stroner

 

[don_resqcapt19]

I would agree with you that there is nothing that says that the large equipment panel or fusible disconnect can be considered as support for the bottom of this conduit run. But since this question has come up I have asked my electrical suppliers and they have never heard of such a rule and also they say if it was, someone out there would be making some sort of support fixture to mount on the backs of these panels. Rich Stroner

Most of the time I see a strut type structure built on the top of or supported from the sides or back of the enclosure if it is a large enclosure.