The extended span table for RMC and IMC - 344.30(B)(2)

[Carultch]

I'm looking at the table 344.30(B)(2), and the conditions that allow you to use it instead of a standard 10 ft support span.

What are some examples of supports that qualify for this use? And some examples that don't qualify? That is to say, preventing transmission of stresses to conduit terminations.

Strut conduit straps?
1-piece / 2-piece straps?
Beam clamp/u-bolt conduit mounts?
Nail up straps?

I would anticipate that it would have to be mounted on a fixed structure to qualify. For instance, a self-weighted rooftop sleeper I'd expect not to qualify. I'd also expect that any span with an expansion fitting or transition to another type of conduit, would not qualify.

 

[tkb]

As long as the strap and supporting structure can handle the weight, you can use the spacing in the table.

 

[Carultch]

As long as the strap and supporting structure can handle the weight, you can use the spacing in the table.

OK, thanks.

I think if the strap and supporting structure cannot handle the weight, one might want to reconsider the design of the structural support.

 

[iwire]

Let the EC decide on the spacing.

Spacing further than 10' can make installation a pain.

 

[Carultch]

Let the EC decide on the spacing.

Spacing further than 10' can make installation a pain.

It's the principle of the concept.

I've got a situation where I either span at 5'-4" or 10'-8", and I'm trying to verify that the 10'-8" span is good enough. All factory segments would have at least one support.