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Author Topic: Burying coax in conduit??  (Read 5332 times)
K8AXW
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Posts: 7042




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« Reply #15 on: February 09, 2018, 10:44:47 AM »

Tisha:  Visualize a 24" water line breaking over a small room full of 480VAC bare copper bus bars, each carrying around 5,000A!  THAT gives new meaning to "boom!"  LOL (now)
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A Pessimist is Never Disappointed!
K0UA
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Posts: 4786




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« Reply #16 on: February 09, 2018, 10:49:36 AM »

A friend of mine dropped a wrench across the -48 volt DC battery plant to a Telephone Central office one time.  Apparently this was before the fuse.  He said the wrench turned white liquid hot and fell into the floor as molten drops of steel.  Apparently there were some repercussions to him.
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73  James K0UA
ARRL Missouri Technical Specialist
WZ7U
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Posts: 1073




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« Reply #17 on: February 09, 2018, 12:14:34 PM »

Gee, ya think? Grin
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K0UA
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Posts: 4786




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« Reply #18 on: February 09, 2018, 02:17:13 PM »

There was an article in the March 2018 QST that referenced the conduit full of water problem and its solution of the drain field.  As that article said, some would not agree with the majority opinion, but I will tell you this, in all of my years of pulling cable into conduits in the ground or concrete touching ground, there are only two kinds of closed conduit:  Conduit with water in it or new conduit that will have water in it very soon.
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73  James K0UA
ARRL Missouri Technical Specialist
AA4HA
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Posts: 2630




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« Reply #19 on: February 09, 2018, 02:39:46 PM »

Tisha:  Visualize a 24" water line breaking over a small room full of 480VAC bare copper bus bars, each carrying around 5,000A!  THAT gives new meaning to "boom!"  LOL (now)
With my incident thankfully there was nobody in the switchgear building when the fountain started.

I too concluded that it is a near impossibility to keep water out of metallic electrical conduit, the threaded joints are just not up to it. It might be a little different for glued PVC (like Sched 40/80) but there still will be that diurial breathing effect (sucking in moist air that condenses).

At my cleverest I had them install a "weatherhead" that had a broad enough sweep for semi-rigid coax to make the bend. We did not pull through it and installed it only after the feedline was pulled through the PVC conduit. It was really smart looking and we did not have to contend with a wad of duct plug seal stuff.

https://www.frostelectric.com/buy/product/pvc-4/111996
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
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