PVC 100% watertight

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Might also want to keep a constant nitrogen or CO2 purge on your line to prevent any condensation from forming in it.
Matter of fact that's the only way to come close to giving them what they want. Send them an RFI about providing nitrogen cylinders and a purge system so the conduit system will meet their specs.

-Hal
 

Coppersmith

Senior Member
Location
Tampa, FL, USA
300.5(G) and 300.7
I live in a subtropical climate. The inspectors here don't enforce these rules. Perhaps it's because they really don't apply unless the panel is in air conditioned space which is rare for a back-to-back installation. If inside, panel is usually in the garage which means temperature is the same at panel and meter. I'll have to ask an inspector about. (They probably have air conditioned garages in Miami.)
 

Smart $

Esteemed Member
Location
Ohio
300.5(G) and 300.7.
Be sure to point out 300.7(A) and 300.9 in your RFI
I'd lead off with 300.5(B)...
(B) Wet Locations. The interior of enclosures or raceways
installed underground shall be considered to be a wet location.
Insulated conductors and cables installed in these enclosures
or raceways in underground installations shall comply
with 310.10(C). Any connections or splices in an underground
installation shall be approved for wet locations.
 

active1

Senior Member
Location
Las Vegas
"There is an instance where it is important to make careful primered water tight joints in electrical conduit and that is where you have a conduit sloping downhill into a basement. Multiple times i have seen a steady stream out of a conduit in such situations due to saturated soil and non watertight conduit joints. Unfortunately it is very hard to stop. There is a special foam product made for the purpose that is reputed to work well."

In general you really don't want to penetrate a foundation below grade.
Ideally is to 90 up out of the ground into an LB or box then enter the structure.
 

kwired

Electron manager
Location
NE Nebraska
"There is an instance where it is important to make careful primered water tight joints in electrical conduit and that is where you have a conduit sloping downhill into a basement. Multiple times i have seen a steady stream out of a conduit in such situations due to saturated soil and non watertight conduit joints. Unfortunately it is very hard to stop. There is a special foam product made for the purpose that is reputed to work well."

In general you really don't want to penetrate a foundation below grade.
Ideally is to 90 up out of the ground into an LB or box then enter the structure.
If other end of raceway is higher then where that LB enters, you still can have same problem.
 

active1

Senior Member
Location
Las Vegas
If other end of raceway is higher then where that LB enters, you still can have same problem.
???

A problem with ground water entering the basement below grade penetration around the conduit? No.

A problem with water entering the raceway say 2' deep and flowing up above grade say 2' in the raceway? Never seen that.
It would take a 4' difference in elevation with the conduit pitched and standing water / saturated soil on the high ground. Naturally the water would just flow down hill unless something caused it to be retained.

Goes back to design. Cristy box, drain hole in gutter / LB / Can, or a penetration in a different location to avoid a potential standing water area such as a loading dock ramp.

Regardless still a lot better then drilling holes in the subterranean foundation.
 

kwired

Electron manager
Location
NE Nebraska
???

A problem with ground water entering the basement below grade penetration around the conduit? No.

A problem with water entering the raceway say 2' deep and flowing up above grade say 2' in the raceway? Never seen that.
It would take a 4' difference in elevation with the conduit pitched and standing water / saturated soil on the high ground. Naturally the water would just flow down hill unless something caused it to be retained.

Goes back to design. Cristy box, drain hole in gutter / LB / Can, or a penetration in a different location to avoid a potential standing water area such as a loading dock ramp.

Regardless still a lot better then drilling holes in the subterranean foundation.
Is dependent on what is the source of the water and elevation of that source in relation to the ends of the pipe - simple hydraulics - if the pipe fills with water higher then one of the ends, it will run out of the lower end.

If ground water level is an issue, you probably don't have a basement in the first place. If you do it is probably flooded a lot regardless.

If you have a well sealed conduit (at couplings and joints below grade) then any water inside is either a result of condensation or maybe missing cap on a weatherhead or bad or missing drip loop on conductors at a weatherhead. Those could still fill the raceway and run into the building once the raceway is filled to same level as the entry point.
 

active1

Senior Member
Location
Las Vegas
Simple hydraulics?
Where have you you ever seen a situation like you described?
Have you ever, I mean ever in your career seen such a situation so remote like you describe?
If you it was a poor design for the extreme situation.

Weatherhead? We're discussing underground.

Groundwater issue you don't have a basement.
Do you get out of Fremont much?
You ever hear of a sump pump, sump pump back up, multiple sump pumps, super seal membrane, or drain tile?

Please keep busting holes in subterranean foundations and goop it up good. I don't care.

But don't, I mean don't contaminate the rest of the internet with your messed up way with the justification that any other way will flood and be worse.
 

kwired

Electron manager
Location
NE Nebraska
Simple hydraulics?
Where have you you ever seen a situation like you described?
Have you ever, I mean ever in your career seen such a situation so remote like you describe?
If you it was a poor design for the extreme situation.

Weatherhead? We're discussing underground.

Groundwater issue you don't have a basement.
Do you get out of Fremont much?
You ever hear of a sump pump, sump pump back up, multiple sump pumps, super seal membrane, or drain tile?

Please keep busting holes in subterranean foundations and goop it up good. I don't care.

But don't, I mean don't contaminate the rest of the internet with your messed up way with the justification that any other way will flood and be worse.
I never said any other way will flood and be worse, just was trying to point out that it still could let water in and gave some reasons why.

I've seen poor drip loop installation cause plenty of water to enter buildings via raceways that were not below grade at all, schtuff happens.

Sump pumps, membranes, drain tile, all can still fail and if you absolutely needed them in the first place because of natural water infiltration - the result is not good. Most avoid having a basement at all in those situations in this area. There is areas here where water table is not very far down at all. One town nearby has almost no basements, older ones that are there have water issues, the few newer ones there may be are usually limited to mechanical rooms and storm shelters, and are on ground that had been built up, not dug down into the water table.
 
Simple hydraulics?
Where have you you ever seen a situation like you described?
Have you ever, I mean ever in your career seen such a situation so remote like you describe?
If you it was a poor design for the extreme situation.

Weatherhead? We're discussing underground.

Groundwater issue you don't have a basement.
Do you get out of Fremont much?
You ever hear of a sump pump, sump pump back up, multiple sump pumps, super seal membrane, or drain tile?

Please keep busting holes in subterranean foundations and goop it up good. I don't care.

But don't, I mean don't contaminate the rest of the internet with your messed up way with the justification that any other way will flood and be worse.

Yes I have seen a river flowing out of a conduit because it was in saturated ground and the joints did not seal. Yes I have seen water flow out of an above grade conduit several feet off the ground due to hydraulic pressure from higher ground.

I dont have a problem with penetrating a foundation below grade in most cases. It depends on the circumstances. There are two concerns: water entering through the conduit, and water entering around the conduit penetration. Regarding the former, that is why I mentioned making quality joints and then that shouldn't be a problem. I have done the up and back down method a few times where I didnt install the pipe and I could tell it had a good amount of flowing water in it. As far as the conduit penetration, it should be a cast in pipe. Also a properly done foundation will be backfilled with stone and daylighted out so there will not be any hydrostatic pressure on the wall anyway. If that is not the case due to not doing it or it was impossible, then you are going to have far greater problems through the floor and eventual cracks anyway.
 
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