Tricks for Identifying Existing PVC?

[kwired]

Uhmmm that's not the "bury part of the code". That's the part of the code that has General Requirements for Wiring. And there is nothing in that part of the code, or any other part of the code, that says anything about transitioning from sch 40 to sch 80 at a given depth.

There is 300.5(D) but unless you read between the lines really should only apply to physical protection of conductors, though (D)(4) could mean Sch80 is required as the protection up to min burial depth or 18" when PVC is the protection.

 

[ActionDave]

There is 300.5(D) but unless you read between the lines really should only apply to physical protection of conductors, though (D)(4) could mean Sch80 is required as the protection up to min burial depth or 18" when PVC is the protection.

Where in (D)(4) does it say anything about transitioning from sch 40 to sch 80?

 

[FionaZuppa]

What part was it that makes it plausible? The part where he says, "The portion of PVC that is visible above ground is painted."
Or maybe the part where he says, "I was just wondering if anyone had any tricks for identifying existing PVC."
Or perhaps it's where he says, "The only (2) things I can think of are (1) dig down until I find some insignia on the PVC... or (2) disconnect/cut a section and measure the Internal Diameter (ID)."
Other than that I guess one could miss the context, but that is pretty much all of the words used to describe the conduit in the OP.

None of that indicates to me a re-use of conduit for a re-wire, or even just a re-use of old existing pipe.

But yeah, you are right, OP seems to be on a quest to determine if some section of PVC pipe is 40 or 80, and w/o any further details beyond that, I did provide a few ways to figure it out.

If the unprotected exposed section is not 80, then it's not compliant anyways, so best to run the fill math using 80, yes? BUT (always a but in there), I think to be NEC compliant when re-using old pipe, either have to pull the old permit and show the inspections (which should list the pipe specs) as a reference, or, have to show it "all" (depth and pipe specs) to the new inspection. This is a gray area as I am not 100% sure of what re-use of old pipe means in terms of installing new ckt(s).


I also believe frostline is a cause for unprotected physical damage, thus you would use 80 to traverse across frost depth for directly buried (covered) PVC. 300.5 does not seem to account for frostline depths, but I think that should be one of the criteria for 300.5. 300.5 should caveat the table with "if frostline is deeper than any of the recommeded burial depths by application, frostline depth shall prevail for sched 40".

 

[Jerramundi]

Are you re-using old pipe, is that the nature of this no-details project?

I'm estimating various possible options, including potentially re-using the existing raceways, yes. The reason for no details is because I've gotten in trouble on the forum before for posting things multiple times. So instead of having ONE post about the various things I'm interested in discussing, I've divided them up into specific topics

Just put a bore scope into the pipe...

How would you be able to tell from the interior aside from measuring it? I don't see how you could perform an ID measurement via scope?

If the pipe you say is painted, so then it's exposed pipe w/o any further protections from damage, then it "should" be 80 if it was inpected off of an old permit, no?

That's cute. You assume the job was permitted. I kid I kid. Just messing with ya. I honestly didn't think about checking for past permits because they had a handyman before me that did a bunch of stuff and to my knowledge, wasn't a licensed electrician. The way the existing PVC stubs out of the ground 3ft into the air without any support before it turns into the building pretty much left me assuming there was no old permit.

And a real valid Q from me. If you re-use pipe to pull new wire, the whole thing is considered new install and you would have to show the pipe before burial, or is that kinda voided if say you can show it (the pipe) listed on a old permit & inspected?

It would be considered new and I will be pulling a permit. I always pull permits when required, even to my own detriment. I didn't pay for night school to be just another hustler. Once the job begins I'll be able to demo part of the existing PVC when I replace the above ground portion with metal conduit and measure the ID.

I was just wondering if there were some trade tricks about determining what size an existing PVC was beyond measuring the OD because to my knowledge, Schedule 80 and Schedule 40 have the same OD. Everyone I've ever worked for has always run metal conduit, less one year experience on cell-towers where we bored PVC through long parking lots. So my knowledge of PVC is limited. My previous employers, less the one, made it out to be some type of boogeyman.

 

[electrofelon]

If the unprotected exposed section is not 80, then it's not compliant anyways,

Where in (D)(4) does it say anything about transitioning from sch 40 to sch 80?

Right, Nowhere. I think many people misread 300.5(D)(4). Lets back up. 300.5 (D) says:

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

Then (D)(4) says:

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,
RTRC-XW, Schedule 80 PVC conduit, or equivalent.

Ok, so I admit its a bit easy to get distracted here, but dont forget we are still under (D) which is "direct buried conductors and cables", so the "Raceway" they are taking about is the raceway in (D)(1), NOT a complete raceway system. Here is what (D)(1) says:

Emerging from Grade. Direct-buried conductors and
cables emerging from grade and specified in columns 1 and
4 of Table 300.5 shall be protected by enclosures or raceways
extending from the minimum cover distance below
grade required by 300.5(A) 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.

So there is not automatic requirement for sched 80 PVC when transitioning from below to above grade. If you consider that area subject to physical damage, then it would be required per 352.10(F). Of course opinion on that will vary. I used to use sched 80 when transitioning but I hardly ever do anymore. I do however religously use expansion couplings, and I feel that play and flexibility makes that transition piece very unlikely to be damaged even if sched 40.

 

[FionaZuppa]

How would you be able to tell from the interior aside from measuring it? I don't see how you could perform an ID measurement via scope?

Usually two things give it away. It has an end fitting on it? They are typically sched40 fittings, so when a 80 pushes up against the stop in the fitting the ID of the 80 will be smaller than the stop ID thus showing a obvious shoulder on the end or the pipe. Another giveaway is easier to see and common practice when using 40 fittings on 80 pipe, and that's to chamfer the end of the 80 so that the shoulder I mentioned before is minimized, thereby minimizing chaffing wire as it is pulled through. So wither look for the obvious shoulder or chamfer. If it's not obvious then it's either 40 on a 40 fitting, or, someone found a 80 fitting to use on the end. 80 fittings are out there but not as common as 40's.

That's cute. You assume the job was permitted. I kid I kid. Just messing with ya. I honestly didn't think about checking for past permits because they had a handyman before me that did a bunch of stuff and to my knowledge, wasn't a licensed electrician. The way the existing PVC stubs out of the ground 3ft into the air without any support before it turns into the building pretty much left me assuming there was no old permit.

That's not good news. If it's all new how do you plan to show proper burial depth (if need be)?

It would be considered new and I will be pulling a permit. I always pull permits when required, even to my own detriment. I didn't pay for night school to be just another hustler. Once the job begins I'll be able to demo part of the existing PVC when I replace the above ground portion with metal conduit and measure the ID.

So you already have a plan....

I was just wondering if there were some trade tricks about determining what size an existing PVC was beyond measuring the OD because to my knowledge, Schedule 80 and Schedule 40 have the same OD. Everyone I've ever worked for has always run metal conduit, less one year experience on cell-towers where we bored PVC through long parking lots. So my knowledge of PVC is limited. My previous employers, less the one, made it out to be some type of boogeyman.

I no magician, so I don't have that many tricks in the bag. Only a few methods that I know of, etc. Trickery is like labeling the wire "12-2" when it's really 14-2 and the reader has no clue what the diff is between 12 and 14.

 

[Jerramundi]

I no magician, so I don't have that many tricks in the bag. Only a few methods that I know of, etc. Trickery is like labeling the wire "12-2" when it's really 14-2 and the reader has no clue what the diff is between 12 and 14.

Haha. "Tricks of the trade" is an extremely common phrase and the word "trick" in that context does NOT carry the negative connotation of deception unless you force it to.

You remind me of my old boss that used to have a heart attack when he handed me a pipe with a mark on it to cut... and I would say something along the lines of "alright, whack it here?" He would lose his mind and scream "you don't WHACK it! you CUT it!" It was hilarious. I used to say it just to piss him off, lol.

 

[electrofelon]

80 fittings are out there but not as common as 40's.

I dont believe there are any RNC schedule 80 fittings. There are schedule 80 fittings, but for other piping systems and not listed as RNC. 352.6 requires fittings to be listed. Of course that doesnt mean someone didn't find and use one.

 

[FionaZuppa]

Right, Nowhere. I think many people misread 300.5(D)(4). Lets back up. 300.5 (D) says:

Ok, so I admit its a bit easy to get distracted here, but dont forget we are still under (D) which is "direct buried conductors and cables", so the "Raceway" they are taking about is the raceway in (D)(1), NOT a complete raceway system. Here is what (D)(1) says:



So there is not automatic requirement for sched 80 PVC when transitioning from below to above grade. If you consider that area subject to physical damage, then it would be required per 352.10(F). Of course opinion on that will vary. I used to use sched 80 when transitioning but I hardly ever do anymore. I do however religously use expansion couplings, and I feel that play and flexibility makes that transition piece very unlikely to be damaged even if sched 40.

I see the issue, it's NEC verbiage once again.

Ok, 300.5(D) refers to "direct burial cable and conductors"
but 300.5(D)(4) starts with "enclosures and raceways". Well, those two things are not cable or conductors, AND, you have to go back and read the NEC definition for "raceway". (D)(4) then says "Where the enclosure or raceway is subject to physical damage, the conductors shall be installed in....."

There's also technically no such thing as direct burial "conductors". Has anyone ever directly buried metal wire that only has a primary jacket? It always has some sort of secondary jacket for contacting earth.

So, (D)(4) carries the words that suggest "conductors in a raceway, where the raceway is buried".

Also, (D)(1) is not correct, it refers to protecting "direct burial cables and conductors" using a raceway. That would suggest the "direct burial rated cable or conductors" are not directly buried at all, they would be in a raceway (see def for raceway). It probably should say "sleeved" to protect the cable or conductors. Which makes sense because you want some sort of protection around the cable or conductors from min bury depth to some distance above grade. As example, you trench, lay in a direct burial rated cable, then use a sched80 long radius 90 to turn up out of the trench and then extend it to some termination point (a box or someting) using 80.

I am reading some other old chatter here on MHF about this very subject, user said he thought he had a newsletter sent out by MH stating that the turn-ups should be 80 if using PVC (and not protected by any other means).

 

[FionaZuppa]

I dont believe there are any RNC schedule 80 fittings. There are schedule 80 fittings, but for other piping systems and not listed as RNC. 352.6 requires fittings to be listed. Of course that doesnt mean someone didn't find and use one.

I just mean in PVC.

 

[FionaZuppa]

There are plenty of other NEC sections that refer to "subject to physical damage", and then refer to "PVC shall be listed for it's use", and to get the damage protection rating I think UL only has that for sched80 PVC (for PVC), etc. So if you apply the "subject to physical damage" to any wires in raceway, or just cable & conductors, if using PVC for the protection, it would need to be sched80 PVC.

 

[electrofelon]

There's also technically no such thing as direct burial "conductors". Has anyone ever directly buried metal wire that only has a primary jacket? It always has some sort of secondary jacket for contacting earth.

Yes, it is called USE-2. Direct bury PV wire is another example.

 

[FionaZuppa]

Haha. "Tricks of the trade" is an extremely common phrase and the word "trick" in that context does NOT carry the negative connotation of deception unless you force it to.

You remind me of my old boss that used to have a heart attack when he handed me a pipe with a mark on it to cut... and I would say something along the lines of "alright, whack it here?" He would lose his mind and scream "you don't WHACK it! you CUT it!" It was hilarious. I used to say it just to piss him off, lol.

I know what it means
So I gave you the trick, use a bore scope.

 

[electrofelon]

So if you apply the "subject to physical damage" to any wires in raceway,

That would be ridiculous. Not everything is subject to physical damage.

 

[FionaZuppa]

Yes, it is called USE-2. Direct bury PV wire is another example.

I did mean for like branch ckt stuff. 338.12 related, etc.

 

[ActionDave]

There are plenty of other NEC sections that refer to "subject to physical damage", and then refer to "PVC shall be listed for it's use", and to get the damage protection rating I think UL only has that for sched80 PVC (for PVC), etc. So if you apply the "subject to physical damage" to any wires in raceway, or just cable & conductors, if using PVC for the protection, it would need to be sched80 PVC.

There is no such requirement in the NEC or the UL.

 

[FionaZuppa]

That would be ridiculous. Not everything is subject to physical damage.

Correct, but conductors coming out of trench, be it conductors in a raceway or a direct burial rated cable or just conductors, that are not protected from the common wheelbarrow, are subject to physical damage. Yes, subject to damage is open for interpretation by the AHJ.

 

[FionaZuppa]

There is no such requirement in the NEC or the UL.

there is.
PVC shall be listed.
and
UL only has sched80 listing (PVC) for "physical damage protection"

 

[ActionDave]

I did mean for like branch ckt stuff. 338.12 related, etc.

So direct bury wire can only be used for branch circuit stuff?

 

[electrofelon]

Are you just trying to argue? You are all over the place

You say there is not such thing as direct bury conductors, then you say "branch circuit stuff" (not even sure what that means).

Then you say one can apply subject to physical damage to any conductors in a raceway, then you say well just this specific part where conductors come out of the ground.....