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Underground service / water in Service Panel


Renron
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Hey Guys!

You all did such a great job on my last question, I'll try another one.

A customer of mine has a Service panel where the feed is from the bottom. No problem yet, here is where it gets interesting. The bottom of the Service Panel is severely rusted, but no rust is present above 1" from the bottom of the Panel. I think water is comming in through the underground service (grey)PVC pipe when it rains hard. The house is down hill from the street, so if there is a crack or disconnection somewhere in the pipe from the drop water can travel downhill and then enter the service panel and run out on the side of the house. I personaly have seen this twice before living in Tahoe. My question is: What does code say about a drain or Pee trap type of arrangement prior to the Service Panel? Can a hole be cut in the PVC before the entrance to the panel and then protected by a screen? I know we don't do "code" checks but I would like to know (for

myself) how to correct this problem without having to dig up the line all the way to the street ~400' away. Any thoughts? [:-banghead]

I am proud to be a (newbie) Home Inspector!

Thanks,

Ron

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You'll definitley want to wait on a second opinion on this, but I don't think allowing the water to drain out of the pipe is really a good answer to the overall problem. There isn't supposed to be any water in that pipe in the first place, so I would say this water should be eliminated, not managed. The wires are almost certainly not rated for such wet use, and the jackets may break down over time and cause a much more serious incident.

PVC just isn't that difficult to put together properly. I'd love to know what the whole story is on this....

Brian G.

Wait for the Gurus Bro'

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There isn't supposed to be water in the conduit? I didn't know that. Seriously, I've never seen a water tight service pipe and never seen anyone go to any extremes to make them water tight. The service at one of my rentals has the top open on the pipe going up the pole in front of the house and I've seen this stuff installed in ditches full of water. I'll call an electrician friend today.

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Wow!

I am very greatful I found this Website, so many people here with experience willing to help everyone out. Thanks for the techinical info Douglas(and others), I had thought that underground conduit WAS suppost to be watertight, I have a lot to learn about inspecting.

Thanks Very Much

Ron

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I stand corrected, if somewhat mystified. Plumbers can glue PVC together without leaks every day of the week, but electricians can't????

Douglas, the ratings info is interesting. Is a "U" indicative of an underground rating then? As in USE? Wouldn't "underground" automatically assume wet location and be acceptable for this purpose as well? I would assume also that regular THHN is not acceptable, which is most of what we see here.

Brian G.

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I'm seeing the aluminum more and more on this as well, though I haven't thought to check the type (new item on my list now). How do you feel about the AL for this use? I must admit it makes me a bit nervous to see AL anywhere in a house, even though I know there's a significant difference between the little soild wire that cause so many problems and the larger stranded types. I assume you would always recommend paste at the connections, but do you see any other potential problems with this set-up?

By the way, if you found a service like this with wiring NOT rated for wet use, how much would you make of it in the report? Would you recommend changing it out?

Brian G.

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Hi Brian,

While we're waiting for Douglas to answer - Aluminum has been used in that application here in the Puget Sound region since the late 60's early 70's without significant issues. It is typical to inspect a home here and find that the S.E.C. and all 240 circuits (dryer/water heater/stove-oven/spas/furnaces) are wired with stranded aluminum while everything else is copper. Most of the time it is coated with anti-oxidation paste, but in those instances where it is not I have never found an issue.

Incidentally, the other day I did a home built in 1972 that was completely wired with aluminum without a gram of anti-oxidation paste anywhere. The house had never been pigtailed and had the original switches and outlets in it. No oxidation anywhere in the house and no corrosion at any outlets or switches. Wrote it up anyway and explained to the client that an insurance company will most-probably see the aluminum wiring as a potential hazard, regardless of its condition, and she can probably expect to pay higher premiums, if she can get insurance at all. I also provided her with some information about pigtailing and warned her about having it done with the suspect Ideal connectors. Since that was part of a development of cookie-cutter homes, I'm betting that all of them have aluminum branch circuitry.

Douglas,

I heard someplace, I don't remember where, that another company has produced a similar pigtailing method to Amp's copalum method and that any electrician is permitted to do it. Have you seen, heard or read anything along those lines? I remember kicking myself in the butt afterward for not asking for more details, but I can't remember who the conversation was with. Such is the onset of alzheimers, I suppose.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by Douglas Hansen

. . .

I used to think this was a rare problem. That you've seen it twice before makes me think we need the product these guys in Hayward are making.

I see it up here now & then when the meter is downhill from the street. It's sort of like an artisian well effect.

Note the attached pictures. On this house, I speculated that the culprit was rainwater entering the conduit way up the pole, near the transformer.

- Jim Katen, Oregon

Download Attachment: icon_photo.gif Martin 01.jpg

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Download Attachment: icon_photo.gif Martin 05.jpg

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I would assume the set-up in Jim's photos is what Chad was describing, more or less. Forgive me all, but that arrangement looks purely bone-headed to me. Why in the world wouldn't you simply install a weatherhead and a drip loop to keep the rain out? If done at installation the extra labor and expense would be minor, at worst.

Douglas,

I have no desire to pester you, so I promise to not belabor the point beyond this post about the PVC. But I must say that I think you're letting the electricians off too easy by conceding out-of-hand that water-tightness is not possible. Isn't it reasonable assume that it is more difficult to keep water "In" under typical household pressures than to keep it "Out" under any naturally occuring pressures? If asked before this discussion, I would have said that water-tight PVC lines were not only possible, but a relatively minor and common accomplishment. I can see where you might have unavoidable condensation, and the inherent wisdom of planning for a leak by requiring water-resistant wiring, but beyond that I'm puzzled. My apologies, I'm hard-headed.

Brian G.

I Blame It on My Genes, My 5 Year-Old is Even Worse

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Interesting, I appreciate the effort Douglas. Of course we were originally discussing PVC, a very different animal from rigid.

If you ever find yourself at an NEC panel / board meeting where these underground services are being discussed, think of me and recommend a weatherhead and drip loop requirement for the next edition. Not being able to keep condensation and minor leaks out is no excuse for throwing the door wide open and inviting the rain in. Take a few of the photos we've seen, show them what happens to the attached equipment in some cases.

Brian G.

Eternal Hard-head

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Brian,

You seem to be missing the point of being "non-watertight". Water in needs to be water out too.

Condensation is going to happen even if the pipefittings are watertight, better to let the lines dry out when possible than to keep it wet all the time. Moisture always travels from warm to cold, ground heats up and the pipe is cold(er)hence condensation. When the pipe warms up to the same temp. as the earth then the relative humidity is the same.

The weather head on the telephone pole is not a bad idea, but, a better one is a wye with a screened vent prior to the service panel. The Wye can also vent moisture from the pipe.

OOOOHHHH!!!!! Brain storm!!!!!!

What if there is a vented wye with screen on both ends of the pipe to allow for ventillation

similar to a closed eves/ridge vent?

Douglas any comments?

Ron

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Originally posted by Renron

Brian,

You seem to be missing the point of being "non-watertight". Water in needs to be water out too.

Condensation is going to happen even if the pipefittings are watertight, better to let the lines dry out when possible than to keep it wet all the time.

Oh I get the point, where I was differing was with the idea that watertightness was "not possible" with PVC in terms of assembling it. Sure it is.

The weather head on the telephone pole is not a bad idea, but, a better one is a wye with a screened vent prior to the service panel. The Wye can also vent moisture from the pipe.

Why not both? It simply does not make sense to point an open electrical conduit to the sky.

OOOOHHHH!!!!! Brain storm!!!!!!

What if there is a vented wye with screen on both ends of the pipe to allow for ventillation

similar to a closed eves/ridge vent?

How would you do that at the service end? Don't they run down the pole and straight into the ground? Most of the ones I've seen also come straight out of the ground into the meterbase...no place for a wye.

Brian G.

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