Electrical: making rainproof conduit connections

Hello,
I'm somewhat familiar with the use of different electrical metal conduits (e.g. RMC and EMT), but I'm wondering what additional procedures are required when making up connections outdoors. A few questions:
1) For an overhead connection to a box (enclosure), a hub is typically held onto the top of the box by 4 screws. Is the mating of the two metal surfaces raintight, or is an additional washer or silicone needed between the two surfaces?
2) For a threaded RMC connection, is any silicone or other thread sealant required?
3) When making an RMC connection to a knockout at the bottom of a box (enclosure), is the use of two locknuts sufficient, or is a different termination fitting required?
Thanks, Wayne
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There is typically no gasket because the metal of the box has a slightly raised collar that fits under the hub. water would run around the collar rather than into the enclosure No sealant is used for threaded pipe Two locknuts is fine for the bottom of the enclosure, be sure to use a threaded bushing

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Thanks RBM for all the info. Sounds like other than using a hub when required, using RMC outdoors is the same as using it indoors.
Cheers, Wayne
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