PVC schedule 80 or 40

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frenchcomp

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Article 300.5 NEC 2005 UNDERGROUND INSTALLATION: (<600V) "where raceway is subject to physical damage, conductors shall be in RMC, IMC, Schedule 80 RNMC or equivalent".

What are criteria which permit or not use of Schedule 40 in direct buried PVC duct bank?

What are North American industrial practices regarding PVC duct bank materials?

Thanks
 
Re: PVC schedule 80 or 40

Where it is emerging from underground or where it is likely to be spaded (installed under mommy's flower garden). :D
 
Re: PVC schedule 80 or 40

Reading UL 651 Schedule 40 & 80 Rigid PVC conduit:
"Schedule 80 rigid PVC conduit are for use wherever schedule 40 conduit may be used and in addition for installation on poles".

Could someone confirm?
Schedule 40 is not considered as a protection for cable damage. Schedule 40 shall not emerge from ground.
When use aboveground schedule 40 must have protection if subject to physical damage.
 
Re: PVC schedule 80 or 40

Your statements are correct, I am not sure what you are looking for since you have already looked at the UL standards. The UL White Book says the same thing and you are required to comply with its listing requirements.

BTW it is on page 25 and category DZYR.
 
Re: PVC schedule 80 or 40

I'm unfamiliar with USA designations like schedule 40(I'm french)and try to make correct interpretation of NEC requirements.
I have difficulties to understand some NEC articles cause they relate products or know-how which doesn't exist in Europa.
I apology if my querries are unappropriate.
 
Re: PVC schedule 80 or 40

WOW, I apologize. I made the assumption that you were in the U.S. The schedule 40 RNMC has a wall thickness of about 1/4 in. and the schedule 80 RNMC has a wall thickness of about 3/8 in. The difference is the strength of the conduits. Sorry but I can't convert the fractions to mm. :D
 
Re: PVC schedule 80 or 40

Charlie - where does it say in the code that you must use Sch. 80 where it emerges from the ground?

I have seen many installations (using Sch. 40) where the conduit emerges from the ground right next to a foundation/structure/pole and is not subject to physical damage (due to its close proximity to the structure).

As as inspector I have permitted this; but if I have been in error I would like to be able to back up future 'correction notices' with some code section.
 
Re: PVC schedule 80 or 40

300.5(D)(4) Enclosure or Raceway Damage.
.."where subject to physical damage"

This is a judgememt call by the inspector, so this call is all over the place, in regards as to what physical damage actually is.
 
Re: PVC schedule 80 or 40

Wayne, I don't have a copy of the NEC in front of me but I believe 300.50 is for over 600 volts.
 
Re: PVC schedule 80 or 40

Good catch Curt. It figures Trying to use the search in the CD NEC again? :eek:
I could have sworn that Mike H. sent out a news letter stating this is required for all conduit exting ground? We have inspectors that site this all the time?
 
Re: PVC schedule 80 or 40

300.5(D)(1) Emerging from Grade. Direct-buried conductors and enclosures emerging from grade shall be protected by enclosures or raceways extending from the minimum cover distance required by 300.5(A) below grade to a point at least 2.5 m (8 ft) above finished grade. In no case shall the protection be required to exceed 450 mm (18 in.) below finished grade.

IMO, schedule 40 is not protection at a pole but schedule 80 is protection. The bottom line is that it is JMO. It is the call of the AHJ. :D
 
Re: PVC schedule 80 or 40

Originally posted by charlie:
Your statements are correct, I am not sure what you are looking for since you have already looked at the UL standards. The UL White Book says the same thing and you are required to comply with its listing requirements.

BTW it is on page 25 and category DZYR.
Click to expand...
I have been looking for this "white book" for ever. Do you know its real name,and how to get it. I have even tried calling the UL and they kept thinking I was saying light book, but when I spelled it out they where at a loss.
Please help if you can. :D
 
Re: PVC schedule 80 or 40

Doesn't schedule 40 PVC have to be incased in concrete, if it is to be schedule 40, otherwise use schedule 80? I might have this backwords. :)
 
Re: PVC schedule 80 or 40

Here is the wording from the UL White Book.

UL MARK
The Listing Mark of Underwriters Laboratories Inc.

Schedule 80 conduit has a reduced cross-sectional area available for wiring space and is suitable for use wherever Schedule 40 conduit may be used. The marking ??Schedule 80 PVC?? identifies conduit suitable for use where exposed to physical damage and for installation on poles in accordance with the NEC.

Roger
 
Re: PVC schedule 80 or 40

The white book is the General Information for Electrical Equipment Directory. You can order it from the UL. The information is available online as the Online Certifications Directory, getting the Guide information. Here is the DZYR information for example.
 
Re: PVC schedule 80 or 40

Originally posted by hurk27:
Dana
Check out 300.50(B) It's required Whether or not subject to physical damage. ;)
Click to expand...
As Curt pointed out, this section is for 'over 600v'. However, there is still nothing in that section that requires ALL PVC emerging from the ground to be Sch. 80....just that PVC associated with 'poles'.
 
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