Schedule 80 vs 40

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wireman3736

Senior Member
Location
Vermont/Mass.
got sited for using sch 40 under a residential drive way. wanted to get it covered so i changed it to sch, 80, Anyone know of a code requirement for this, the work was in MA,:-?
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
Unless the you have a local code, you only have to follow the depth requirements in Table 300.5. The NEC doesn't care what you use....
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
"cited" by an authority enforcing NEC or POCO (or both) ??

(Some of our local POCOs required 80 under a drive..........)
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
The vagueness of 352.10(F) as to what locations could be considered physical damage leaves a wide field for interpretations.
By policy or practice, the local AHJ may consider that a "damage" location.
As I say, some local POCO's do,
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
true....
but as the (unenforcable) FPN notes, Sch 80 is for Physical Damage areas (supported by the UL White Book as I recall) .. this "interpretaion" area had led to many local requirements for using Sch 80.
 

wireman3736

Senior Member
Location
Vermont/Mass.
I always use 80 under roads or parking lots, I just don't see the problem under a small residential drive way. Like i said I just wanted to be able to get it covered up so it wasn't a big deal to change it,
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I understand and agree with your action.
To clarify my reply, the wording of the NEC and UL (DZYR-White Book) referencing Sch 80 for "Physical Damage" locations with no definition of such leaves us all open to any inspectors interpretation as to where it just be used.
 

kwired

Electron manager
Location
NE Nebraska
Which leaves the question - why is it subject to damage?

If he is worried about possible future excavation trenchers and backhoes don't seem to care if you use sch 40 or 80 and even RMC is not enough sometimes.

Would he allow direct burial rated conductors to be installed in the same location as long as they meet minimum depth requirements?

This is just stupid.
 

pete m.

Senior Member
Location
Ohio
It's been said on this site probably a gazillion times.... ask for the code section, whether local or NEC, that you are supposedly in violation of. That is the only legal way I know of that a job can be defected by an inspector.

Pete
 

renosteinke

Senior Member
Location
NE Arkansas
It's an interesting paradox: just how deep need the pipe be? After all, it can be enough to 'protect' it with nothing but 4" of concrete - which would be the driveway itself.

Such a shallow depth, though, begs the question of what happens to the pipe after it exits the slab. Then you might be required to have the pipe buried as much as 30" down (HUD rules for mobile home feeds). That's quite a transition.

How the pipe is placed also matters. If you bored a hole under an existing slab, there's no way for you to properly fill and compact the soil around the pipe.

I suspect that the inspector in this case is trying to strike a balance: "I'll let you run the pipe a bit shallow IF you use a stronger pipe." Since Article 110 has general requirements for wiring methods to mechanically protect the wires, there is some room for discretion on the part of the inspector.
 

iwire

Moderator
Staff member
Location
Massachusetts
I suspect that the inspector in this case is trying to strike a balance: "I'll let you run the pipe a bit shallow IF you use a stronger pipe."

Who said it is shallow?


Since Article 110 has general requirements for wiring methods to mechanically protect the wires, there is some room for discretion on the part of the inspector.

:roll:
 

wireman3736

Senior Member
Location
Vermont/Mass.
I guess the answer to my question is there is no nec requirement to use 80, and i don't see any requirement in the ma. amendments. I just believe the inspector was misinformed about the requirements, if I just threw direct burial in the ditch and ran no pipe then he probably wouldn't have mentioned it. It wasn't a big deal to change it this time. :)
 

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
i guess the answer to my question is there is no nec requirement to use 80, and i don't see any requirement in the ma. Amendments. I just believe the inspector was misinformed about the requirements, if i just threw direct burial in the ditch and ran no pipe then he probably wouldn't have mentioned it. It wasn't a big deal to change it this time. :)

300.5(5)(d)(4).
 

jumper

Senior Member
300.5(5)(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.

Mike, how are conductors under a resi driveway in schedule 40 PVC subject to physical damage as a general rule of thumb?
 

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
n
(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.

Mike, how are conductors under a resi driveway in schedule 40 PVC subject to physical damage as a general rule of thumb?

It is the opinion of the POCO and others that the gravel, #2s - "fines", can compact and damage the pipe.

Now do I believe that 80 is better than 40? To me that is saying that the "rhythm method" is safer than "protection". Both can fail.
 

jumper

Senior Member
n

It is the opinion of the POCO and others that the gravel, #2s - "fines", can compact and damage the pipe.

I thought OP said this was not a POCO service install.

Now do I believe that 80 is better than 40? To me that is saying that the "rhythm method" is safer than "protection". Both can fail.

Okay, you lost me.:confused: ( I do understand the analogy, but not how it applies here). Any install can fail, the question seems to be " What is required by the NEC for reasonable safety under the conditions described?".
 
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