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Joined: Oct 2000
Posts: 2,749
Member
Someone found this problem at a newly constructed site. The water was actually boiling when the site lites were energized.

[Linked Image]

The electrical contractor installed a nonmetallic junction box below grade, and then fabricated a 4 inch square cover to it to allow a riser conduit for the support and to feed a sign lite.

[Linked Image]



[This message has been edited by Joe Tedesco (edited 02-18-2003).]


Joe Tedesco, NEC Consultant
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Joined: May 2001
Posts: 717
G
Member
Great one, Joe.
I wish I had a camera but I was a bit 'busy' that day.....We had one of our institutions trip out, which of course started a panic. I went to the substation..where it went from 12.5 to 4,160, and isolated the shorted circuit, by then I was joined by 3 other guys. When I saw which circuit was out, it was a quick deduction.

The institution had been wired around the turn of the century, it was the standard to put pole transformers in a vault, there was only one of these originals still left, and that was the circuit. The sump pump had failed and the vault was full of water. That was a 15 X 15 room, 10' high with about a 6' collar.

The entire thing was still boiling when we opened the manhole lid, but hey, didn't take long to dry once we pumped it [Linked Image]

Joined: Nov 2001
Posts: 745
M
Member
Joe:
Hate to ask what is probably a stupid question, but...is the water boiling because of a fault in this poor installation? (I guess it makes sense, though; if a fault can get hot enough to start a fire, it can get hot enough to boil water, as in George's case)

Mike (mamills)

[This message has been edited by mamills (edited 05-02-2002).]

Joined: May 2001
Posts: 717
G
Member
Water boils in this type of thing because it is conducting electricity. I think we can assume faulty splice in the case of the pic. Maybe simply made with wirenuts and not approved for underground/underwater use. Faulty, maybe not, improper, definitely.

Joined: Apr 2002
Posts: 10
D
Junior Member
Well, it's not exctly boiling if the water is exposed to electricity. It's electrolysis. it is being divided into hydrogen and oxygen, or if there's other things in the water, the products are different.

Joined: Sep 2001
Posts: 806
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Member
Would you actually get electrolysis (with "boiling" production of gases) with an AC current? Every demonstration of the process that I have seen uses a DC current. I would think that the chemical reaction would reverse itself 120 times per second, with the generated H2 and O2 recombining rather than building up at the electrodes as they do with DC.

Joined: Oct 2000
Posts: 2,749
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Any additional thoughts concerning the boiling water?


Joe Tedesco, NEC Consultant
Joined: Feb 2002
Posts: 183
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Member
Water (ok, not pure water) is conductive due to dissolved materials. Apply a potential through it and it will heat up. I remember vaporizers (humidifiers) that worked that way - the linecord terminated in two rods that were immersed in the water. Add just enough salt to reduce the resistance and it would boil.

Joined: Feb 2003
Posts: 939
F
Member
also as long the device is not sealed it can relase the vapor from the source.

if it was in sealed box or device it will blow the gasket out or go thru back to the power source where the breaker or fuse box is located.

myself i did see one of the device did boil the water pretty good later i learn that the ground wire and neutral wire was pretty corroded and cause all the water in the box vaperized and see the box inside all green

oh yeah one more thing that the boiling water can burn your hand if you dont look out !!!! [Linked Image]


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


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