Schedule 40 vs. Schedule 80 PVC conduit underground
Schedule 40 vs. Schedule 80 PVC conduit underground
(OP)
I'm upgrading the service to my house. I intend to put it in underground. The Utility requires schedule 80 PVC pipe that is exposed near the meter base and at the service pole.
There is about a 75 feet from the pole to the house where the new service entrance will run. The Utility told me to run a conduit underground. This section where I intend to put it screams for some landscaping that either I or the next owner will surely put in. I can see rototillers, spade shovels, etc directly over this conduit and cable.
I just wonder for safety's sake would it be better to install Schedule 80 the whole way, encase schedule 40 in concrete, and if I did encase it, or dig it down deeper...is schedule 40 good enough?
There is about a 75 feet from the pole to the house where the new service entrance will run. The Utility told me to run a conduit underground. This section where I intend to put it screams for some landscaping that either I or the next owner will surely put in. I can see rototillers, spade shovels, etc directly over this conduit and cable.
I just wonder for safety's sake would it be better to install Schedule 80 the whole way, encase schedule 40 in concrete, and if I did encase it, or dig it down deeper...is schedule 40 good enough?






RE: Schedule 40 vs. Schedule 80 PVC conduit underground
If you encase it, then Sched 40 is surely good enough.
Also, when using Sched 80, make sure you use the correct conduit fill calculation, since the ID is reduced compared with Schedule 40.
David Castor
www.cvoes.com
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
I don't know whether schedule 40 is adequate, but I would think the extra thickness from schedule 80 would be worth the investment.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
There is certainly nothing wrong with the schedule 80 if you take dpc's suggestion and account for the reduced internal diameter, but I'd probably run sch40. I never liked the idea of direct bury cable when placing it in conduit isn't difficult.
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If it is broken, fix it. If it isn't broken, I'll soon fix that.
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
PVC is brittle, and can and will be damaged by rototillers and spades. That's why the sch 80 is required at the risers; a little better for fending off lawn mowers and trimmers that might contact it.
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
There is no problem going from Sched 80 to Sched 40 right?
This is a 200A service. The extra fill requirements for the Sched 80 must be why they asked it to be 2-1/2" instead of 2".
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
One last thing; be mindful of your jam ratio if you are pulling 3 wires at once.
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If it is broken, fix it. If it isn't broken, I'll soon fix that.
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
While others may pooh-pooh this, my coworker had that exact thing happen to him, and this is a million-dollar home, to boot.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
> bad sealing on the conduit
> citywide storm drain debris prevention
> big rainstorm that overflowed the storm drains
The second one is the most annoying. Why bother having storm drains if you're going to prevent rainwater from getting to them?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
Are you saying that water seeps into the conduit and into the meter base even if the meter base is 5' above grade?
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
Likewise, there wouldn't be burrowing animals and tree roots that do other sorts of damage...
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
Water can enter the conduit albeit very minor amount of water unless the conduit is connected to a vault that happens to collect water from a parking lot or something like that. If there is a chance that water will enter this conduit from a vault or utility connection to a vault than the standard installion would include a 30" x 30" handhole with drain near the service entrance riser, with conduit broken (not continuous) at the handhole. The handhole will prevent hydrostatic pressure build up.
This sounds unlikely but I have witnesses a large hotel service entrance that was flowing water like a waterfall down the finished interior walls because the CT enclosure was well below the utility vault several hundred feet, away that was collecting water. As a utility concerned with liability, we dug down to the LV conduit and chopped a hole into the conduit while the service remained energized. Water 'geysered' up about 10' from the conduit: it is possible to build up substantial flow and head in a large interconnected conduit system.
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://virtualpipeline.spaces.live.com/
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
When you say a vault are you talking like a manhole? And how does water get it to them if they are all sealed PVC conduits coming into them? Matter of fact I don't really understand get how water is getting into any of the conduits underground. It certainly doesn't get into the plumbing system does it?...so why the electrical?
BigInch, the Utility came out and told us to put it in conduit and run it to their service pole and they would do the job freebie....so actually I don't have a lot of choice. And as others have described here, there are some additional benefits to running conduit - easy replacement, added protection. And when conduit is less than $100 for the whole job, I think its worth it.
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
Electrical conduit is a completely different animal. It has no internal pressure and it is open on both ends. Water will therefore find its way in. Sometimes it happens quickly, other times it takes years. It all depends on the design and installation.
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If it is broken, fix it. If it isn't broken, I'll soon fix that.
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
Turbinegen, Water should be assumed to get into anything placed underground. In fact I've hardly ever seen a conduit that wasn't full of water, or had evidence of it, even in Saudi Arabia. Its only a matter of time. That's why the NEC requires UG ratings for cables placed in underground conduit, if I'm not mistaken. Water DOES get into plumbing systems quite often, as they do not normally run "pressurized" (they're usually designed for open channel flow; atmospheric pressure everywhere only, thus are always sloped) and at times groundwater even infiltrates into potable water supply pipes through lose joints or cracks in the pipe. One of the reasons that septic tanks must be placed away and lower than the nearest water supply piping. They do run pressurized sometimes, most notably after a heavy rain when you see water blowing off the manhole covers, but otherwise, no. However at the same time, when soil water tables are also high, outside hydrostatic pressure can exceed inside pressure even of potable water piping and enter into the pipes, as you correctly note.
As a matter of practice, I wouldn't drill holes in conduit, but rather leave a drain point at the last pull box before connection into a building. Water will get in there one way or another, so it only makes sense to let it get out. A small hole somewhere won't let out enough of it to make any difference anyway.
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://virtualpipeline.spaces.live.com/
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://virtualpipeline.spaces.live.com/
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
NEC 250.53 requires raceways enclosing service-entrance conductors to be arranged to drain.
The idea of the drain hole is not to drain all of the water out of the conduit, but to prevent water from getting high enough to get into the house.
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://virtualpipeline.spaces.live.com/
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
"Scientists dream about doing great things. Engineers do them." -James Michener
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://virtualpipeline.spaces.live.com/
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
Yes a weep hole could conceivably let water in, however that is why you should put this at a low point in the system and hopefully have the service entrance into the building at a higher elevation. Some of this stuff is too basic for engineers, yes?
RE: Schedule 40 vs. Schedule 80 PVC conduit underground
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://virtualpipeline.spaces.live.com/