Encapsulating a circuit

[Brian Logan]

I'm encapsulating a circuit that has 230V present and may from time to time be
completely submerged in water (including the wiring entering the encapsulant). I
understand that standard epoxy is good enough at keeping water/moisture out, but
I also understand that the hard part is sealing between the cables and
encapsulant. Looking through the Google news archives I came across one post
that mentioned the use of "special irradiated PTFE wires" as the epoxy
_chemically_ bonds to this, whereas it doesn't to PVC cable. Not sure what the
"special irradiated" bit is. Can't get in touch with the original poster. Anyone
any other suggestions as to how to seal cables properly?

Cheers

Brian

 

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You might try cross-linked polyethylene. Good water
resistance, and glues better than many other insulations.

 

[Brian Logan]

Thanks, for the suggestion. I had a search for it and there doesn't seem to be
much mention of it. Would you happen to know if it is readily available, or is
it a bit specialist?

I would have thought that adhesion to cables was a common problem with
encapsulation, but it's surprising how little mention there is of it. :-(

 

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It's a bit of a specialty item for the electronics trade. The
power and lighting people use it in 18 AWG (I think), and that should
be available as a catalog item. You will probably want try it out
with a variety of epoxies. You will want to talk to some epoxy people
(like Masterbond) about the right epoxy to use . It will help if you
have enough quantity in this to have a custom epoxy made if required,
and also custom wire or cable. The wire and cable people will do this
for as little as a few thousand feet.