This was a previous question with some great answers. How can I adapt a wall outlet to suface mount conduit? One answer was: "There are collar boxes available that have conduit KO's (knockouts). Just install one on top of the existing device box and run your conduit." I was wondering if there was a way to do this while maintain weather proofing of the outlet for outside applications? Is there a gasket box extender that could be used? I have a plug I would like to adapt to conduit that is on a partially covered porch. It would not be exposed directly to rain or weather but could potentially get wet.
The appropriate extension box will look like this. Hole plugs in unused openings then conduit can be run on the surface for an additional outlet with a weather tight box.