Water Wicking In Lighting

[rc0213]

We are designing lighting that has water wicking issues. We have connection to wiring on both sides. But, somehow, they are still accumulating water. We use 14 - 20 GA wires, normally in the 16 - 18 GA range. The wire is stranded. Someone thought that tinning the stripped ends might help. I saw only a couple of companies have a shrink wrap they sell with some epoxy to seal the ends of the harness.

So, we would like any suggestions from other engineers who work with harnesses in the outdoor and is exposed to the environment. What do you suggest?

Thanks in advance,

 

[MacGyverS2000]

I'm assuming you mean the water is wicking inside the protective sheathing...

Sealant is the only way to go... self-healing tape (the stuff that sticks to itself) is one method if you're doing a few manual installs. If you need speed, get the snap-on connectors that are filled with gel. I cannot speak as to the long-term longevity of those connections in terms of water ingress, however.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[IRstuff]

Seems like you've not provided sufficient information
> are the lights on all the time?
> what kind of environment are they in?
> what does the physical layout look like?


TTFN
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[itsmoked]

If you're talking about the housing (not clear) then often the daily pressure swings pump air and water vapor in and unfortunately just air back out of it resulting in a pool of water that can run the humidity up to 100% in the enclosure when the sun hits it.
Sometimes venting the enclosure with a felt dust/bug filter on the very bottom stops all the pumping action plus it allows the condensation to dry out daily.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Keith's answer is a good one, I see this so often with enclosures which have good IP ratings yet still accumulate water internally. A breather usually solves the problem.

Other options... use a filled cable rather than one with formers or tracers. 'Old-fashioned' cables with a textile thread former are the worst for water wicking. Or use a barrier gland at the entry, although that could get expensive.

 

[rc0213]

Thank you all for your inputs, I really appreciate it!

To clarify, in more detail, this design is a lighting electrical circuit for a vehicle. So, this wiring is exposed to the environment. And, the light is on only during the vehicle operation. The heat output is very minimal, since the LED being used is running around .07 Amps. There was a suggestion of using encapsulated wiring. The little I could find out seems to be the answer.

My question is, does anyone know how much more expensive encapsulated wiring is versus regular stranded? And, is there any pros and cons on the encapsulated wiring?

There are some suggestions that might apply to my design, but for now, we are pursuing the encapsulated wiring. So, I need to learn about it from you, and see if it is really feasible. If not, I will try some of your suggestions.

 

[IRstuff]

The water accumulation might not specifically be wicking, which has a certain connotation about the physical mechanism. Presumably, the ends of the cable are not exposed to a liquid water environment? If not, then how can there be "wicking?" Is there a sheath around the individual wires?

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[BillPSU]

It depends on what voltage your LED are operating at. Currently at my companty we have to control water ingress on harness connections which are either 5 volt or 12 volts. We build construction equipment which used EH valves(electo-hydraulic valves). Normally we us dielectric grease to control ingress and try to keep all connections turned horizontal to stop any pooling.

Previously I worked at an aerial device and digger derrick manufacturer. People were up to 102 feet in the air working on live power lines. Connection to control circuit were critical. All harness ends were the screw together water tight connections. The connectors had either solder connection pins or crimp on pins. The connectors were potted after being assembled and then a heat shrink sleeve was used to cover the pin connections. This manufacturer now has machines which take people over 200 feet in the air.

How much liability is in your application and what are the risks if something fails?

Good Luck
Bill

 

[jraef]

But to your earlier point, you CAN get heat shrink tubing that has a hot-melt sealant in it. Used heavily in marine environments.

http://www.te.com/usa-en/products/harnessing/heat-shrink-components.html

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