NM underground in conduit

[bphgravity]

In early October, my jurisdiction will be having a contractor workshop and conference to discuss changes to inspection requirements and to go over any issues the contractors may have. Our director has instructed us to come up with issues we are seeing in the field that we wish to have changed or at least reviewed for change.

One issue I have not liked since the moment I started woring here is our allowance for NM to be installed in underground/under slab/in the slab raceways to islands or floor recptacles etc..

It's apparently not enough to simply state, "it's not to code", so I am trying to determine te real issue or problem with this allowance. Other than the obvious code violation, is there a true hazard or potential hazard in the long term permitting this to continue. Many other jurisdictions in the area have enforced UF or individual conductors with wet location listing. At this point, our director feels this practice has never been a real problem and it does not make any sense to force contractors to change now.

Any help or thoughts about this.?

 

[benaround]

Re: NM underground in conduit

Bryan,

This is just a list of thoughts about such subjects.

1. They say that code rules can be traced back to a real hazard.

2. It seems that things like this have a way of coming back to bite you.

3. The out of town boys will be using UF cable,the home boys will be using NM.

4. The young guns in town will never know it can not be done elsewhere until they get tagged .

5. If you are going to send a message,make it read like you want it to read.

6. EC's live with constant changes,on the job,NEC,customers,etc. This would be a good time to make it right.

7. Good Luck and I hope you can convince the others.

 

[tom baker]

Re: NM underground in conduit

Underground conduit is considered a wet location-especially in Washington State. NM is not listed for wet locations. I have seen THHW fail in underground conduits with water.
See article 100 definition of location, wet. one way to address this issue would be to adopt a local code admendment that allows NM in conduit.

 

[allenwayne]

Re: NM underground in conduit

Look at 300.5 D 5.had a home that started as a spec home and then wanted a floor box . So we retro a floor box.About 6 months later the rains started and water was coming from the cpvc that fed the masterbath.Filled that box full of water .
someone just pointed out plumbers use cleaner/primer/glue to keep water in but eletrictricians only use glue and that won`t keep water out