Conduit in road

Status
Not open for further replies.
O

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Master Electrician
I am running 1" Sch 40 pvc in a residential dirt road driveway with 6-8" of cover for a fiber line. Its in the mountains so 6-8" will be all we can get because there is a lot of rock.

My question is do I have to worry about this pipe being crushed by vehicle traffic?

I have googled crushing strength of PVC but I would hope its a lot higher when it is buried.
 
I would think 6 inches would be really shallow.

Going across, or along the length?

If going along the length, maybe going straight down the middle would be less like to get driven over
 
You might sleeve the PVC conduit with a couple 10ft. lengths of 2" galvanized rigid conduit if it's running across the driveway. Or use GRC instead of the PVC conduit.
 
The first question we always get asked is “How deep do we bury the wiring or cable?” That’s a great question. And the answer is that it depends on what wire you use and whether you run it within a conduit or not. Since most people ask the question so that they can meet a particular desire for maximum burial depth, let’s start there. Breaking it down by how deep you bury the underground electrical wiring when you install it, we have the following options:

24-inches Deep Burial Depth

  • Use direct-burial underground feeder cable at 24-inches deep (or more). You don’t need to use conduit at this depth with UF cable, however, you do need to provide PVC conduit on your vertical feeds starting at 18-inches.
18-inches Deep Burial Depth

  • You can run THWN-2 conductors inside of PVC conduit at just 18-inches deep in the ground. This protects the wire from damage in the event someone digs overtop of the cable. THWN-2 is basically water-resistant THHN (Thermoplastic High Heat-resistant Nylon-coated wire)
12-inches Deep Burial Depth

  • At 12-inches deep, you can run direct-burial feeder cable wire that is GFCI-protected. Protect it with PVC where it pops up at the house, garage, or shop.
6-inches Deep Burial Depth

  • If you use galvanized EMT (metal electrical conduit) with individual conductors inside, you can bury it just 6-inches deep. The idea here is that the EMT can withstand a shovel or other significant potential cause of shorting the wiring.
 
The code dictates conduit types and burial depths, your looking for our acceptance for you to violate the NEC.
“In the mountains” has no code reference, if it’s rocky run galvanized rigid conduit, which will reduce burial depth, but increase installation cost.
 
And yes, there is significant risk that the conduit would get crushed.
 
scrubbin said:
6-inches Deep Burial Depth

  • If you use galvanized EMT (metal electrical conduit) with individual conductors inside, you can bury it just 6-inches deep. The idea here is that the EMT can withstand a shovel or other significant potential cause of shorting the wiring.
Click to expand...
Wouldn't that be rigid metal conduit, and not EMT?
 
olly said:
I am running 1" Sch 40 pvc in a residential dirt road driveway with 6-8" of cover for a fiber line. Its in the mountains so 6-8" will be all we can get because there is a lot of rock.

My question is do I have to worry about this pipe being crushed by vehicle traffic?

I have googled crushing strength of PVC but I would hope its a lot higher when it is buried.
Click to expand...
Burial depth has been mentioned.I reviewed Art 770 on my cell phone and I did not see a reference to table 300.5, if this is customer owned fiber.

(See 90.3) for why table 300.5 does not apply
If this a utility application then the NEC does not apply

You could use Sch 80 pvc. As mentioned, concrete encasement can be done. A locatable warning tape or locate wire with fiber in the conduit is a must.

Running down the middle of the road is not a expected location, typically fiber idd add on the side of road with warning signs
 
scrubbin said:
The first question we always get asked is “How deep do we bury the wiring or cable?” That’s a great question. And the answer is that it depends on what wire you use and whether you run it within a conduit or not. Since most people ask the question so that they can meet a particular desire for maximum burial depth, let’s start there. Breaking it down by how deep you bury the underground electrical wiring when you install it, we have the following options:

24-inches Deep Burial Depth

  • Use direct-burial underground feeder cable at 24-inches deep (or more). You don’t need to use conduit at this depth with UF cable, however, you do need to provide PVC conduit on your vertical feeds starting at 18-inches.
18-inches Deep Burial Depth

  • You can run THWN-2 conductors inside of PVC conduit at just 18-inches deep in the ground. This protects the wire from damage in the event someone digs overtop of the cable. THWN-2 is basically water-resistant THHN (Thermoplastic High Heat-resistant Nylon-coated wire)
12-inches Deep Burial Depth

  • At 12-inches deep, you can run direct-burial feeder cable wire that is GFCI-protected. Protect it with PVC where it pops up at the house, garage, or shop.
6-inches Deep Burial Depth

  • If you use galvanized EMT (metal electrical conduit) with individual conductors inside, you can bury it just 6-inches deep. The idea here is that the EMT can withstand a shovel or other significant potential cause of shorting the wiring.
Click to expand...

I think you missed the part about this being a sleeve for a fiber line.
 
tom baker said:
Burial depth has been mentioned.I reviewed Art 770 on my cell phone and I did not see a reference to table 300.5, if this is customer owned fiber.

(See 90.3) for why table 300.5 does not apply
Click to expand...

Also 770.3 says: "Only those sections of Chapter 2 and Article 300 referenced in this article shall apply to optical fiber cables."
 
olly said:
I am running 1" Sch 40 pvc in a residential dirt road driveway with 6-8" of cover for a fiber line. Its in the mountains so 6-8" will be all we can get because there is a lot of rock.

My question is do I have to worry about this pipe being crushed by vehicle traffic?
Click to expand...

Besides crushing, PVC might get abraded and/or punctured by being pushed around against sharp rock over a period of time.
And even if RGS is used alone or as a sleeve, embedding it in a relatively small amount of concrete, cement, or mortar could help keep it in place and avoid having it move around under the forces of traffic.
 
Status
Not open for further replies.
Top