Electrical Preparation-now what?.....

[Brewman]

Couldn't hurt to check with your inspectors first- they'll tell you what they'll allow, and possibly your plans are fine.  Not all areas enforce rigidly to the NEC.
Brewman

[BobRex]

Check with your local inspector before you change over to "stacked" breakers.  The NEC may allow them, but individual areas can be stricter than the NEC and not accept them.  That happened to me when I finished a basement a few years ago.  In an effort to save space, I used a few piggyback breakers in my panel.  The inspector made me take them out and run a sub panel instead.

[Brewman]

Good point, and a good reason to apply for an electrical permit, and get all required inspections.  The NEC is more of a guideline than anything, is way open to interpretations, and what the local authority says always supercedes the NEC
Brewman

[leaky]

Home now, and have checked a few things out.

-Contractor did indeed run conduit with 3 wire plus ground, so I'm okay there.

-Measured the PVC conduit that I had run under the slab, and it's 1", so I'll need to neck it down if I want to run 3/4" flex line.

-Checked the main box, and it's a "3 wire" service, where the ground and common bus is shared.

-The main breaker is 100 amp.  That may cause an issue, although I'm not sure.  Maybe if we're running both ovens and a bunch of other things along with the tub......

-I tried to put a meter in the 220 outlet in the garage to verify that it is the dedicated 50 amp breaker, but can't get a reading due to the "three input" configuration of the plug.  

Now 2 more questions:  How can I check the circuit at the 220v plug, and what gauge wire should I buy to run from the pull box to the spa itself?

[Brewman]

Test your volt meter on a 120v outlet that you know works, to be sure your meter is funtctional.
Then test the 240v outlet.
If the circuit is hot, you should get a 240v reading by putting your volt meter probes to the two hot slots on the outlet.  You should get a 120v reading if you put your probes between a hot terminal and the neutral.
Same with hot and ground if your panel bonds the neutral and ground bars together.
No juice? check the breaker and reset it if it's tripped or shut off, retest.  
Still no power?  Be absolutely sure that you have the correct breaker, and shut it off.  Then remove the outlet plate, and check to see if you can attach your meter probes to the wires instead of the outlet prongs.
You may have to pull the outlet out of the box, do this carefully.  
If you have the breaker on, and the wires test dead, maybe they are disconnected from the breaker.  Again all this assumes you have the right breaker.  Be careful.
Usually you'd run 6 gauge copper THHN/THWN wires from your disconnect to the spa.  Sometimes 8 gauge neutral and ground might be allowed.  That is up to your inspector.  And check the spa manual to see what wire gauge they recommend, and follow it.
Brewman

[tootall]

# 6 Gauge wire white red and black & number 8 gauge for ground. That is what Marquis owners book states.

[leaky]

Some updates:

-Got most of my materials at the HD yesterday.  Picked up a non-fused 60 amp pull box per Brewman's suggestion.  I had to do some modifications, as the box had no hole punch out on the center of the bottom face, and that's where I needed it (I had my contractor stub the electrical PVC straight up in front of the box on the side of the house).  I drilled out & filed a new hole, trimmed the cover to clear the fitting, then threaded in the PVC fitting for a perfect fit.  After placing the box over the opening on the wall and threading the wires through the back, I marked the locations of the mounting holes.  It was then I discovered that the leads coming out of the house are too short to reach the terminals on my pull box!  I have no real choice but to slide on some shrink tubing and solder some jumpers on to get them to reach...

-I saw that the Marquis requires 6 gauge wire with an 8 gauge ground.  I have a HS pre-delivery book that states they require at least 10 gauge.  I checked the #6 conduit at HD, and I think the ground in it is no bigger than 10 gauge, if that.  As a result, I think I'll run individual wires rather than conduit to the spa.

-I followed Brewman's advice and pulled the 220v outlet in the garage, and put my meter to the bare wires.  The 50 amp circuit in my panel is indeed dedicated to this unused circuit, so I capped off the wires and will use that slot in the panel to insert the 60 amp breaker and wire the spa to.

-I also got a bundle of 3/4" flexible conduit, a bag of clamps, and all the other fittings and adapters I'll need.  Getting more excited every day!!!

Thanks to all who are helping me along.  You have been a blessing.

[stl-rex]

Code does not require a receptacle to be installed for the  spa however if you do have a receptacle by the spa code requires that it be atleast 10' away and be a gfi.

And what if it is not?  We are considering putting a tub in a spot adjacent to an existing 110 outlet.  One corner of the tub would be 2 ft from that GFCI outlet.  I'd rather not move it if I don't have to and the location is the only acceptable one for the tub.

[Brewman]

Code may or may not require the outlet, but your inspector sure might.  Mine checked for the existance of the outlet, implying that it HAD to be there.  Luckily it was, but not due to anything but luck.  
So check on that before you complete your wiring, it's often easier to do this stuff at the same time.  

If code is enforced, you will have to move or remove that outlet, it needs to be a minimum of 10' from the spa water (not the spa itself, but the water, as the crow flies).  

Two possible (but not all possible) outcomes- You remove the outlet, cap the wires, and put a cover plate on the box, and are allowed no outlet serving the spa.

Or you are forced to install an outlet in the 10' to 20' feet zone.  

All depends on your inspector.  Check before doing anything to your wiring so you don't waste time of money.
Brewman