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#178063 - 05/22/08 02:30 PM Underground Junction  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
Doing a repair at a church, the parking lot lights have PVC running from the building to the lights, but between they have a green electric box in the ground with the PVC running into it and spliced with W/P connectors, but there is no sealed enclosure with these boxes and water can get in the PVC and eventually corrode the wires. Is this a legal installation?


The Golden Rule - "The man with the gold makes the rule"

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#178070 - 05/22/08 05:56 PM Re: Underground Junction [Re: aldav53]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,830
Brick, NJ USA
Yes, what you describe sounds like a compliant install. Any conduit 'buried'/outside is considered a wet location, hence the conductors must have a "w" in the insulation designation (ie: THHN/THWN).

A quazite type box is an approved method.



John

#178071 - 05/22/08 06:06 PM Re: Underground Junction [Re: HotLine1]  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
Hard to believe the THHN-THWN is good for wet locations since the wires corroded and shorted out. I had to replace them. I somehow have to seal off the PVC so water won't get into the pipe again. Seems to me it should be like a round floor outlet box - completely sealed. Low voltage may be ok for this, but can't see how 120v could be safe or code.
I've seen the power companies use these green boxes underground for splices from their transformers. Guess they have there own code.


The Golden Rule - "The man with the gold makes the rule"

#178074 - 05/22/08 07:54 PM Re: Underground Junction [Re: aldav53]  
EV607797  Offline
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Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
You are correct: Utility companies do not have to make their installations compliant with the NEC, nor do federal government facilities. In most cases, utility standards are much higher than those mandated by the NEC and government facilities are still NEC compliant even though they technically do not have to be.

As for the green hand hole box, those are usually meant for housing underground sprinkler controls. There's not much effort made to make them even remotely watertight since there's no need to keep water pipes dry. I would be willing to bet that this isn't part of the original installation. There was probably an above-ground J-box that kept getting hit by the grounds keeping people. A handyman probably took a trip to Home Depot and came up with your current "solution".

A true Quazite box will be somewhat more tightly-designed to keep as much water out as possible. Of course, with an open bottom, there's not much that can be done about rising water from the bottom. You can dig down as far as possible and fill the base with gravel to aid in quick disbursement of collected water though.

Of course, the best thing to do is to situate the splices as high up as possible so that the likelihood of their sitting in standing water will be minimized. If the wires are solid, they will usually stay upright on their own. When stranded wire is used, I'll sometimes just bang a short piece of 1/2" PVC pipe in the ground and secure the wires to it with a cable tie or two. If this still concerns you, you could always get a PVC junction box that fits within the confines of the hand hole. You can then extend the existing conduits into the bottom of the box. If they won't all work into that plan, maybe you can cut some of them back a bit and extend them into the proper position.

It's true that THWN wire is rated for wet locations, but that doesn't necessarily mean that people should go crazy with assumptions. My guess is that it wasn't necessarily the wire insulation itself that caused the issues you are having. I'd imagine that the splices being submersed in water cause enough corrosion to result in excessive heating during dry conditions. Over time, this heating caused the insulation to deteriorate.

If you decide to keep the box as-is, just try to keep the splices as high up as possible and also try to situate the wire nuts so that they are vertical (wire openings facing down). At least no water will get in due to the cover leaking and any ground water rising will have to come WAY up. Even then, it might not stay very long if you put a decent amount of gravel in the bottom.


---Ed---

"But the guy at Home Depot said it would work."

#178076 - 05/22/08 08:09 PM Re: Underground Junction [Re: EV607797]  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
Yeah, probably do that, also, seal off the pvc ends so water doesn't get in there. How can this be code?.. the top of the green box says "Electric" on it, don't think it means low voltage only.
Was thinking on your line of suggestions though, Thanks,


The Golden Rule - "The man with the gold makes the rule"

#178079 - 05/22/08 08:39 PM Re: Underground Junction [Re: aldav53]  
EV607797  Offline
Member
Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
Unfortunately, it is. Hey, you can even splice wires without a box when they are directly-buried in the ground with an approved splice kit. This also includes approved tapes and sealants, not necessarily any kind of splice kit or enclosure. Once it's outside, the rules change dramatically.


---Ed---

"But the guy at Home Depot said it would work."

#178081 - 05/22/08 08:51 PM Re: Underground Junction [Re: EV607797]  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
Yep, but thats different.


The Golden Rule - "The man with the gold makes the rule"

#178086 - 05/22/08 10:49 PM Re: Underground Junction [Re: aldav53]  
EV607797  Offline
Member
Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
I don't like it either, but that's the way it is. All that I can say is to try to do it right as best you can.


---Ed---

"But the guy at Home Depot said it would work."

#178087 - 05/22/08 11:11 PM Re: Underground Junction [Re: EV607797]  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
ya right.. :-)


The Golden Rule - "The man with the gold makes the rule"

#178095 - 05/23/08 06:53 AM Re: Underground Junction [Re: EV607797]  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,207
Chesapeake, VA
THWN is suitable for wet locations, but that doesn't mean exposed stripped wires won't corrode. The terminations also have to be made up with a method suitible for wet environment, completely enclosed, and set up-right so any water will drip out instead of pooling up.

Originally Posted by EV607797
You are correct: Utility companies do not have to make their installations compliant with the NEC, nor do federal government facilities. In most cases, utility standards are much higher than those mandated by the NEC and government facilities are still NEC compliant even though they technically do not have to be.
Back in the day, the government had all their own codes, but there's been a push in recent decades to go with commercial standards. Several government agencies have adopted IBC and NEC as the official buildings codes; DoD and NASA I know of for sure, and a few others too. Of course, the facilitiy owners are their own AHJ, so...


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