Wiring up a 20amp 240volt outlet

[GilSwillBasementBrews]

I haven't been able to verify from searching. Tried posting in a similar thread in electric brewing but got no response and was hoping to get this going 5hrs from now when I am done work so figured I'd get more views here. So when wiring an 20amp 240volt outlet it says use 2 hots to the posts and neutral/ground to the ground screw. Aren't neutral and ground 2 different things? Are they interchangeable? I would assume ground is ground is ground why have it if neutral serves the same purpose??? Any of the qualified electricians around here want to enlighten my ignorance???
The reason I ask is I am trying to step down a existing 30amp dryer feed to a spa panel and 20amp breaker and outlet. The dryer feed is 10/3 (2 hits and a neutral) and the wiring diagram I found for 20amp 240volt outlet said to wire ground/neutral to the ground screw in the outlet. If this is ok I can use the existing 10/3 wire if they're not interchangeable I will need to pull a ground wire from somewhere to tie into the outlets ground. The spa panel I got also only has the 2 hot connections and a single bus bar for the neutral leg. If I do need a seperate ground where/how would I go about connecting that to the spa panel. I had read older wiring sometimes would connect ground and neutral to the same bus bar and just want to verify that is safe before I electrocute myself accidentally while thinking I was ok.
Thanks anyone who helps out with this.

 

[Scout]

Well... in a 120 volt circuit the neutral is the return. The ground is there as a safety, if the hot energizes the frame or chassis the ground will keep you from being electrocuted. And yes, once in the breaker panel both ground and neutral go to the same bus bar.
In a 240 volt circuit, there is no need for a neutral, unless the appliance has a light bulb or clock or something like that. (Electric stove) You will still need a ground though. Does your ug have two prongs or four?

 

[IslandLizard]

I did see your post in the electrical forum thread. That's where you should expect the right exposure and answers.

Doesn't the 10/3 dryer feed have a bare copper conductor? That is the ground wire. Red + black are both phase. White is neutral, which is bonded to the ground bar at the service panel. 4 wires and a 4 prong receptacle/plug is code for modern dryer/stove type installations where a 120V feed is needed for the electronics in addition to the 240V feed for the elements. The reason for the neutral wire is that the ground wire won't carry any current (return of the 120V), and is a true ground.

For your IC3500 you only need 2 hots (black and red) and the ground. There is no 120V service needed.

Why the spa panel? Just a NEMA 6-20 receptacle would do it.

 

[GilSwillBasementBrews]

No the dryer wire is just red,black,and white. The reason I got the spa panel is the dryer feed is 30amps and the induction plate has a 20amp plug so I want to splice the dryer feed into the spa panel with the 20amp 240volt breaker then out to the 20amp outlet for the induction cooktop. So I am assuming I will just terminate the white to the neutral bus bar in the spa panel then run a separate ground wire to the 20amp outlet instead of using the neutral to the ground screw in the outlet.

 

[IslandLizard]

As long as the white wire is connected to the ground bar in your main panel, you can use it as the ground conductor to your Spa panel, and your 6-20 receptacle. No need to run a separate ground wire from your Spa panel or receptacle back to the main panel.