We are installing a hot tub on our deck and need a little advice. We ran a 6/3 wg sheathed electrical cable cable across the basement and out thru the wall above the deck. At this point do we need a service disconnect, and then run a wire from the disconnect to the hot tub? What kind of disconnect would you recommend? Also, the wire will be running under the deck and will be in damp conditions at times. Is UF wire available in 6/3 or do we need to run conduit into the tub? Thanks for your help!

If you are using a GFI breaker at the panel, then a non-fusible AC disconnect would work. If you are using a standard breaker at the panel, then a hot tub disconnect with a 50A gfi breaker would be necessary.
Use 3/4 Liquitite conduit from the disconnect to the tub and run 4 pieces of #6 or #8 THWN wire (2 black, 1 white, 1 green)for your power wires. You can use #8 here if the tub instructions allow it because you are running THWN and not sheathed electrical cable.