When installing the new Raintite connectors in a threaded device do you use the rubber washer? On some lights and boxes the female threads start resessed and you can't get but one or two threads but if you remove the washer you can get a good connection. I was taught if it was threaded it was water tight. What are your thoughts? Rod

I haven't used them yet but I would say that you need the "O" ring. Threaded is not necessarily leak proof and this is especially the case with Bell boxes and connectors. It all depends on whether the full taper of the threads on the fitting or conduit fully engage the threads of the box. That's possible with threaded rigid or IMC conduit but with most fittings the limit is reached when the hex or shoulder contacts the box.

-Hal

Welcome to the forums!

THe fitting must be used as per the mfg instructions. There are/were an instruction/installation sheet in the last few boxes of RT EMT fittings we bought. I can't say fore sure, but I believe the O-ring is to be used. The UL listing of RT fittings was revoked a while back, as the 'old style' fittings were not 'RT'.

A gut answer will be "use the O-ring"

John

Danm not what I want to hear but I do see your point. On a horizontal run I am more worried about a tight connection, the threads are short I do not see how water can enter if you have 5 threads but what do I know I have only been at it for 26 yrs. Do we have to put rubber gaskets on ridgid too? I am not talking about the ring on the Emt just the crush washer. If 5 threads is good for explosion proof why is it not good for weather tite?

Because for explosion proof, all the threads do is provide a long enough path to cool the escaping gases below the ignition point of the surrounding atmosphere. They DO NOT have to completely prevent leakage.

Pipe threads generally aren't leakproof without some kind of sealant. Plumbers need to use teflon tape, pipe dope, etc. to keep threaded pipe joints from leaking.

I would use the O-ring unless the instructions say to omit it.