Sizing rigid for soow

[Worlds Gr8est Electrician]

I am doing some remodeling of some waste water pump sites. Some of the pumps need new rigid ran from control panel to the wet well containing the pumps. I am to rework the leads from the pumps into the new Rigid. The specs say to size RMC to existing wire size.

So I went to Chapter 9 note 9 and it said flexible cords of 2 or more conductors shall be treated as one conductor. I then got on the internet and looked up 8/3 SO to see the total area.

8/3 so has a area of .720

So if I go to chapter 9 Table 4 (RMC) it tells me I need 1 1/2" RMC

Am I correct. Also is there somewhere in the code book that tells you the area of SO cord. I checked Article 400 and nothing jumped right out at me. Thanks guys

 

[iwire]

I think one of the reasons you are not finding how to size a raceway for SOOW is because cords are not allowed in raceways.

400.8 Uses Not Permitted. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:

(6) Where installed in raceways, except as otherwise permitted in this Code

Now I know what you are planing is common but I do not any code section that allows it.

All that said I would not use less than 1.5" for 8/3 cord and might use 2", it will not pull easy.

 

[Worlds Gr8est Electrician]

Thanks for the reply. I knew about 400.8 but chapter 9 note 9 sounds like we are aloud to do it. Like you said it is common practice. We do it all the time with new well sites. The 21 well sites we are remodeling are all done this way as well.

Thanks for confirming the pipe size. For ease of the pull I will probably step it up to 2 inch if my boss is cool with it.

 

[Cow]

I haven't pulled SO through conduit in a while but we used to wipe baby powder all over it so it'd slide through the conduit a little easier. Everyone looks at you funny when you get that stuff out though....

 

[Girl Engineer]

Do the specs say something like "Install in accordance with the NEC" or "with all applicable codes"? If so, you need to bring it back to whoever wrote the spec, and ask them, "Which is it?"
But as an electrician, you should know better. Will a state inspector be inspecting your installation? If so, I would save yourself the work and do it right.