long conduit run above OR below ground.

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  #1  
Old 05-21-15, 05:33 PM
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long conduit run above OR below ground.

Have a long conduit (1 or 1.5" PVC) run to make to sub panel (200+ ft).
This run is thru brush on a very rocky slope of about 15 degrees average.

Options:

1) Bury schedule 40 so top of conduit is >18" down. I know this will work but it is alot of WORK.

2) Just lay schedule 80 above ground. I've looked thru NEC and can't find anything against it. If I burried the schedule 80 I would still have to go 18" but the electrical code allows schedule 80 above ground in traffic areas.
a) I don't think I have to comply with expansion provisions as would not be a straight run with secured ends.
b) needs to be supported every 6 feet but it will lay on ground so this is not an issue.


I would rather just bury the schedule 80 4-6" but that does not look like an option.

Anyone see any issue with Option 2 (just routing schedule 80 above ground)?

Thanks
 
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Old 05-21-15, 06:16 PM
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Welcome to the forums!

You did not say how big of a circuit you are running but if you can get by with 120 volt, 20 amp circuit you can bury it 12" with GFCI protection.

If you put it on top of the ground I think you would a have a few code violations:
1) You would have to comply with the secure/support rules of PVC. Every 3' for 1" or 5' for 1.25'/1.5" (It is required to be secured AND supported)
2) You still can only have 360 degrees of bends
3) It can not be subject to severe physical damage (IE: tree falling on it)
4) It would likley not pass the "workman-like manner" required by the code.

How about running rigid or IMC? You only have to bury that 6". You could convert it to PVC for your risers for ease of bends.
 
  #3  
Old 05-21-15, 07:51 PM
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My reading of 352.30 Securing and Supporting Is that the securing in accordance with 352.30(A) refers to close to the termination points:

(A) Securely Fastened
PVC conduit shall be securely fastened within 900 mm (3 ft) of each outlet box, junction box, device box, conduit body, or other conduit termination...


While the supported is covered by 352.30(B)

(B) Supports
PVC conduit shall be supported as required in Table 352.30. Conduit listed for support at spacings other than as shown in Table 352.30 shall be permitted to be installed in accordance with the listing. Horizontal runs of PVC conduit supported by openings through framing members at intervals not exceeding those in Table 352.30 and securely fastened within 900 mm (3 ft) of termination points shall be permitted


The ground will provide support at spacing <5 feet (for 1.5 inch PVC).

Item 4) I would drive anchors every 10 feet or so (that provided loose connection to PVC for expansion) even if the code did not require. I think something like this would be required to come close to meeting "workman-like manner".

Item 2) Thanks for reminding me ... but not an issue in this case (< 360 bends total)

Item 3) No issue like that. Only damage would be caused by fire (seems to occur every 20-40 years). But I have not seen this as a catagory (usually talking about forklifts etc. ) there will be no traffic in this area.

IMC is a possibility but alot of cost for no added improvement.
(unfortunately >20 amps so don't get the 12" exemption but thanks for reminding me of this because it is applicable to another front yard run)

Thanks Again
 
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Old 05-22-15, 08:49 AM
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Of course we can't see it, but I have a hard time believing an inspector would accept a conduit on the ground as safe from damage. Perhaps you could make the case for sch 80 pipe if it is in an area where vehicle traffic is not possible. There is also the issue of the pipe being secured, which usually means attached to something substantial like concrete or framed walls. Outdoors we only would use 4x4 or 4x6 treated posts to support anything electrical. The code does specifically prohibit using any kind of trees or vegetation for support.

I have occasionally seen arrangement like this in a temporary situation like a construction site, but usually there would be temporary barricades or signage. Just a pipe running on the land seems sketchy.
 
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Old 05-22-15, 08:55 AM
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I too cannot see a loose conduit laying on the ground as meeting the code requirements to be secured and supported.
 
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Old 05-22-15, 11:46 AM
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I agree with the comments.

The above ground meets the letter of the NEC.
Except for the "workman-like manner" that I need to check is in the code.

Unfortunatly the inspectors out here are letter of the law folks... which means if I burry it ... the top of the conduit had better never come closer than 18" below surface.
 
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Old 05-22-15, 11:54 AM
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Neat and workmanlike is almost unenforceable as it is too vague. What I consider neat may be someone else's sloppy.
 
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Old 05-22-15, 11:56 AM
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NEC 110.12. Mechanical Execution of Work. "Electrical equipment shall be installed in a neat and workmanlike manner." Some editions refer to ANSI publications for further clarification on "workmanlike manner", but it essentially boils down to doing things the way the majority of professionals in the trade believe is the right way to do it. Installing a pipe that is a tripping hazard could certainly be considered "un-workmanlike" for example.

Regardless of any of that, the big issues are protection from damage, support and securing of the pipe. Any of these could sink this plan in their own right without the need to invoke 110.12.
 
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Old 05-22-15, 12:09 PM
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I think many inspector would default to commonly accepted installation practices to determine neat and workmanlike.
 
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Old 05-22-15, 02:53 PM
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Installing a pipe that is a tripping hazard could certainly be considered "un-workmanlike" for example... Regardless of any of that, the big issues are protection from damage, support and securing of the pipe. Any of these could sink this plan in their own right without the need to invoke 110.12.

This pipe would be supported by the ground almost continuously (5' increments allowed for suspended PVC, which can droop in the sun). In 20 years not a single person has ever crossed the line in question (see photo below, covered in brush 4-8 feet high on a slope).

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Never the less... I still agree that someone will probably find a reason to object. In an ideal world I could just bury it shallower 6", but unfortunately we live in a one rule (18") fits all world. I thought it might be possible to catch them up based on the lack of rules regarding above ground.
 
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Old 05-22-15, 03:35 PM
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I mentioned it before, but I will again, I would run 1" rigid or IMC buried 6" down. It will cost more than PVC but safety is never cheap. Remember, this installation will likely outlast you, at least it should.
 
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