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#209941 - 05/16/13 02:42 PM Underground Risers  
akmaster  Offline
Joined: Jun 2012
Posts: 70
Is there any code section requiring risers and the 90 from a duct bank to be schedule 80 PVC or Rigid Conduit? I think it comes down to physical damage but on the job we have a 13.8 duct bank of schedule 40 pvc that has pvc 90's and risers that I feel need to be and the SPECS call for galvanized rigid conduit..

any help on what NEC says would be appreciated...see pic attached.

Thank you,


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underground.JPG (41 downloads)

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#209942 - 05/16/13 03:38 PM Re: Underground Risers [Re: akmaster]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,057
300.5(D)(4) is what you are talking about.


(D) Protection from Damage. Direct-buried conductors and cables shall be protected from damage in accordance with 300.5(D)(1) through (D)(4).

(4) Enclosure or Raceway Damage. Where the enclosure or raceway is subject to physical damage, the conductors shall be installed in rigid metal conduit, intermediate metal conduit, Schedule 80 PVC conduit, or equivalent.

It still brings up that ambiguous "subject to physical damage" thing.

Greg Fretwell

#209943 - 05/16/13 03:52 PM Re: Underground Risers [Re: akmaster]  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,799
Brick, NJ USA
The 'over 600 volts' (300-31 to 300-50) basically is what Greg said above.

That said, who wrote the 'Specs' you referenced above??

'Specs' should be followed, or a letter from the writer (assume an engineer) allowing a change should be obtained.


#209944 - 05/16/13 03:53 PM Re: Underground Risers [Re: akmaster]  
akmaster  Offline
Joined: Jun 2012
Posts: 70
Thank you Greg!



Don't drive and TEXT! Drive now TALK LATER!

#209945 - 05/16/13 05:14 PM Re: Underground Risers [Re: akmaster]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,057
I used to see a lot of RNC sweeps on these risers because pulling wires around those corners can actually cut into PVC.
Around the water, they can still rust out so it is going to be a compromise around here.

Greg Fretwell

#209984 - 05/20/13 01:48 PM Re: Underground Risers [Re: akmaster]  
Yoopersup  Offline
Joined: Mar 2003
Posts: 822
We always Put RSC 90's As gfretwell said. for the same reason. Lots of times the nylon pull string or the pulling rope would pull thru the 90's. If the RSC 90 extends above ground it should be bonded. Utility companys as well as others use PVC u guard & sch. 80 up the pole.
Just my 2 cents worth

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