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#190826 - 12/07/09 11:05 AM Water in the wire. How to stop the migration
mikesh Offline
Member

Registered: 06/07/06
Posts: 614
Loc: Victoria, BC, Canada
I have an 800 amp service that has water in the service conductors. Parallel copper 500 KCM before compacted wire. IE there are little spaces between each strand which over the last 40 years have filled with rain water. Recently we had the utility remake the terminations but the tails from the pole mounted transformers just let water funnel into the bolted connections where by capillary action, a little head pressure the drip in one end translates to a drip at the other end. The wires have been in the pipe a long time and the water has been flowing for a few years hence the need to replace the guts in the switch. The conductors have been ringed and there are adequate drip loops but once a drip gets into the conductor its partner is displaced and comes out at the terminals of the main switch.
My question is this, How do we keep the drips out? I an contemplating a sealed hypress lug that is used to reduce the terminal size or even a cadweld connection. This is becoming a common problem and the utility has had a few problems with water getting into the wire, especially the non compressed wire of days gone by.
I have thought of solder, can't get it to stick to the oxides, Epoxy or sealant injected down the wire, etc.
This is way beyond what a notch on the insulation can help since the water is inside the wire.
The utility conductors literally funnel the water into the taped connections and water transfers inside the tape from 1 conductor to the next. The difference in height is about 10 feet from the top of the main switch to the terminations at the utility. Changing the wire is a last option as I am sure these can't be pulled out so a new service raceway and conductors would have to be installed at a multi thousand dollar cost.
Any solution has to be OK'd by the utility engineers.

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#190829 - 12/07/09 12:40 PM Re: Water in the wire. How to stop the migration [Re: mikesh]
NJwirenut Offline
Member

Registered: 09/15/01
Posts: 816
Loc: Bergen County, NJ
Heatshrink tubing with a hot-melt adhesive liner? Cover the barrel of the lugs and a few inches up the wire jacket.

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#190830 - 12/07/09 01:07 PM Re: Water in the wire. How to stop the migration [Re: NJwirenut]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5300
Loc: Blue Collar Country
You're goung to have to replace the wire - the only way to dry it out is to 'cook' out the water by running excessive amps throught it for an extended period.

Now, in a pinch, under PROPER engineering supervision, ypu might be able to pull this off by TEMPORARILY using just one set of the paralleled conductors. A lot depends on just how many amps will actually be running through the wires, and whether you'll be able to monitor / inspect the insulation for damage. PVC begins to decompose at about 250F, so you'll want to keep your temps well below that.

Assuming you get the wires well dried, yet still warm, I'd try to get some silicone grease to wick in before sealing the connections thoroughly. Even traditional self-fusing tape will make for a waterproof connection (though heat shrink sure is easier to remove later).

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#190831 - 12/07/09 01:11 PM Re: Water in the wire. How to stop the migration [Re: mikesh]
feather Offline
Member

Registered: 02/28/06
Posts: 25
Loc: Santa Maria CA USA
One possible way is to pressurize the dry side terminations with dry nitrogen. Three or four PSI should do the trick, however the copper has already taken damage. If you replace the cable, a filled strand (poly acrylic dust) is available.

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#190834 - 12/07/09 04:02 PM Re: Water in the wire. How to stop the migration [Re: feather]
mikesh Offline
Member

Registered: 06/07/06
Posts: 614
Loc: Victoria, BC, Canada
We have had a short piece removed when the cable was re terminated and the individual strands are in pretty good condition so I am not too concerned that the copper has oxidized to some green paste. Reno I am not concerned about the water in the wire but a drip in equals a drip out. I was only thinking I had to stop the drip in. NJ wirenut, the heat shrink is fine for preventing the water from getting in through the connection but the wires from the transformers into the lugs are transmitting the water that gets in and a compression lug is not stopping the flow. The nature of the wires and splices don't stop water from getting out of 1 wire and flowing into the next. I know 1 mechanism is capillary action and I have seen it raise a column of water a foot or two. If even a few drips of water make it to the weather head it starts to syphon at least a few drips more until the vacuum breaks.
Feather how do you pressurize the wire what tool? If it bubbles the water would stay put wouldn't it?

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#190835 - 12/07/09 04:38 PM Re: Water in the wire. How to stop the migration [Re: mikesh]
feather Offline
Member

Registered: 02/28/06
Posts: 25
Loc: Santa Maria CA USA
Our 500 mcm is .736" in diameter. Use a 3/4" copper tubing tee fitting, this will give you a gauge port. I get dry N2 from our oxy-acetylene supplier. You'll need a gas regulator to reduce bottle pressure to safe level. This is how filled strand cable is tested using dies to check migration.

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#190836 - 12/07/09 04:58 PM Re: Water in the wire. How to stop the migration [Re: mikesh]
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
This problem certainly won't go away unless you can 100% prevent the initial water entry from the utility end. I can vividly remember my cousin filling junction boxes in underground mains with molten pitch in the late forties, [because I got a whack round the ear'ole for throwing a stone in the pot!]. I'd guess a modern equivalent would be a compound-filled gland - maybe like this?

http://www.douglaselectrical.com/?gclid=CLax-fSwxZ4CFVBd4wodfDDUog

As to the water already in the wire- most of that's probably in there for good. Question is, how long will it take before it all fails due to corrosion?
_________________________
Wood work but can't!

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#190840 - 12/08/09 01:28 AM Re: Water in the wire. How to stop the migration [Re: Alan Belson]
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
Stop further water invasion...

Over time the wicked water will go away.

Corrosion is not a killer problem with nearly pure rain water.

///

To stop further water invasion use every manner of underground rated epoxies...

Talk to 3M and their peers.

The way you describe your situation one can imagine it practically squirting water up into the bus.

The more I think upon your situation the more I think that te water is coming from damaged feeder insulation.

Have you Megged it?

Do that first.

Then get back with us...
_________________________
Tesla

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#190844 - 12/08/09 10:40 AM Re: Water in the wire. How to stop the migration [Re: Tesla]
mikesh Offline
Member

Registered: 06/07/06
Posts: 614
Loc: Victoria, BC, Canada
The guts of the switch and the terminations were checked for leakage current and passed the engineers report. The main switch was re-certified about a year ago.

I can't see water damaging a copper wire, after all it carries water if it was a pipe. There should be no air so what reaction would the copper face? A little oxide on the surface but there is not enough flow to migrate any oxides so I expect they would stay put. Ice could become a problem but it does not go more than 3 or 4 degrees below freezing here and the load should help to prevent ice forming inside the wire.
Epoxies might be the ticket but how do you get it in? Will they affect the termination or conductivity of the connection? Most methods of preventing water from getting into the building are geared at the raceway or outside of the wire.
Many years ago I had water get into the wire through the notch the electrician placed in the drip loop. It actually allowed a stream of water to spray over the CT's in the metering section. We fixed that with rubber tape just by breaking the surface tension on the wire. that also was non compacted wire.
I am hoping for a tried method that has been proven effective. I am sure there is a solution out there that works but what? even a $5000.00 bill that fixes it is way cheaper than 6 X 90 foot lengths of 500 mcm and 2 of 350 copper plus the digging, pulling and down time in winter.

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#190845 - 12/08/09 10:55 AM Re: Water in the wire. How to stop the migration [Re: mikesh]
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
Watertight mil-spec shipboard cables are gel-filled or include expanding fillers that stop the penetration of water. These fill all the cavities in the wire, and prevent water from wicking through it. This is only to prevent compartment-to-compartment flooding through severed cables, though; all connections are always made in watertight boxes. Thankfully, you don't need to worry about this, just the jacket integrity and the connections. There should not be any water anywhere near the end of the utility's termination. It should be sealed and watertight.

Copper corrodes, even when immerse entirely in freshwater due to dissolved gasses, impurities, and simply the natural corrosive properties of H2O itself. Bottom line is you need to keep the water out, not in. Plugging the indoor end with a giant wad of RTV might be a stop-gap and get you into warmer weather, but you're going to need to replace the cable.

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