Water cooling cables

Hi,
Does anyone know of a case where a 250 kva transformer has "cooling"
water in the underground conduit carrying its cables? Stated another
way, does the NEC allow water to be used to cool cables in an
application like a strip mall? This transformer feeds a building with
small retail shops and the cables do NOT appear to be special purpose
cables. My guess is that water leaked into the conduit and the
electrician explained it as "water to keep the cable cool". I am NOT
an electrical engineer but I am simply seeking a little information
before taking my observation to the next level.
Thanks for opinions,
Mac
Reply to
OldMac77
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Franky speaking, underground conduit usually has problem on water inside conduit. The water can cool down the cable BUT not the initial design idea (The water also causes leakage if cable is damage).
Reply to
Samuel Chan
No, Water sometimes gets into conduits but it is not there for cooling. Any application needing cooling would use oil or sulfur hexafluoride and would have heat exchange fins, pumps, fans and other accouterments associated with the installation. There would never be just water alone.
Is this guy a licensed electrician? Take it to the next level.
Reply to
Bob Eld
The inside of conduits installed underground is a wet location by the 2008 NEC. Cables installed in these conduits are required to be listed for wet locations. That would be cables with insulations such as XHHW, THHW, THW, but not THHN. The W has to be in there. Water often is found in these underground conduits because conduit is not water tight. However, the water is an anomaly that we live with and is not part of the "cooling" effect and is not part the calculation for ampacity.
Reply to
Gerald Newton
Hello All,
Thanks for the helpful replies. This guy is The Contractor! Not his apprentice! This matter is definitely going to be reported to the next level.
Best wishes.
Reply to
OldMac77
Think about that carefully. This guy might have told you the story about water cooling just to jerk your chain. He may know better and "the next level" may know that he knows.
Reply to
Paul Hovnanian P.E.
I am almost sure I'd have the last laugh, he may even know that too. I gave him enough clues. If this guy has a position of trust and can set out to deceive me, we do not need him. Along with other documented transgressions, I have the authority to terminate him. ("Next level" person =3D me, "Next level" action=3D termination.)
Regards to all,
mac
Reply to
OldMac77
The "design criteria" for below grade wires in conduit is that it might be flooded and it might be dry but it should work in either situation.
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Reply to
John Gilmer
quoted text -
Jerk chain deceive
I bet you're a fun guy at parties too.
--=20 Keith
Reply to
krw
|
|> Franky speaking, underground conduit usually has problem on water inside |> conduit. The water can cool down the cable BUT not the initial design idea |> (The water also causes leakage if cable is damage). | | The "design criteria" for below grade wires in conduit is that it might be | flooded and it might be dry but it should work in either situation.
Right. The appropriate "W" rated wire should be used. Expect the conduit to be perpetually flooded.
Reply to
phil-news-nospam
|
|> Hi, |> |> Does anyone know of a case where a 250 kva transformer has "cooling" |> water in the underground conduit carrying its cables? Stated another |> way, does the NEC allow water to be used to cool cables in an |> application like a strip mall? This transformer feeds a building with |> small retail shops and the cables do NOT appear to be special purpose |> cables. My guess is that water leaked into the conduit and the |> electrician explained it as "water to keep the cable cool". I am NOT |> an electrical engineer but I am simply seeking a little information |> before taking my observation to the next level. |> |> Thanks for opinions, |> |> Mac | | No, Water sometimes gets into conduits but it is not there for cooling. Any | application needing cooling would use oil or sulfur hexafluoride and would | have heat exchange fins, pumps, fans and other accouterments associated with | the installation. There would never be just water alone.
SF6 is good for thermal transfer?
Reply to
phil-news-nospam

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