This question is about the BNC connection interface itself and not how the coax is attached (assume the coax is attached in a rain-proof way).

While inspecting a male BNC connector we noticed that there is a rubberized gasket in the back that the female side presses against tighly when latched. I checked all the male connectors that I had nearby and they all had the gasket:

Male BNC with Rubberized Seal

Looking at the female side, a touch of dielectric grease on the outer metal ring to mate with the gasket should keep water out (and indeed, the grease might not be necessary).

I've looked around and while all pictures seem to have this gasket, I have found no reference to BNC connectors being rain/waterproof by design even though it appears as though they might already be rain-proof. (There do exist rain-proof connectors that address the cable interface, but in this question I want to know if it happens that the connection itself is already rain-proof by design.)

Does anyone know for sure?

Female BNC

  • 2
    $\begingroup$ Not an answer, a rule of thumb, call it Marcus' law of comprehensive marketing if you will: if a product might have a universally desirable property and it's not advertised, then it likely doesn't have that property. $\endgroup$ Nov 29, 2022 at 10:33

1 Answer 1


According to the BNC spec, connectors are only required to pass "moisture resistance" test MIL-STD-202(Method 106) whose specific purpose is:

The moisture resistance test is performed for the purpose of evaluating, in an accelerated manner, the resistance of component parts and constituent materials to the deteriorative effects of the high-humidity and heat conditions typical of tropical environments.

Since there are so many different idiosyncratic definitions for "rain, resistant," I'll leave it to you to interpret what that means for your locale and use case.

Related, many vendors sell BNC connectors that are also IPX rated (an environmental resistance standard).

  • $\begingroup$ Pardon my ignorance, what is IPX? $\endgroup$ Dec 9, 2022 at 15:07
  • 1
    $\begingroup$ updated answer to include info $\endgroup$
    – webmarc
    Dec 9, 2022 at 15:20

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