240v help!

[eblend]

Hello guys,

Been doing 120v electrical for a while on the garage and the basement, but this is my first attempt at 240 volt, and I am confused!

Here is the background.
In the house, I have a double braker which crosses over from both feeds, so I get 120v on each braker for a combined 240v. From here on I have a 10-3 wire running underground to the garage sub panel. In the house the 10-3 cable is connected in the following way (red to braker 1, black to braker 2 on the dual braker), white to neutral and the uninsulated copper to the panel itself.

In the garage, the other end of the 10-3 cable is connected like this.

Red to one phase, black to the second phase, white to neutral and copper to the ground. Okay everything up to this point is fine and everything works. In the garage I have a few single brakers that are used for lights ect. Now, this is where I am getting confused. I want to install a 240v plug and a 240v heater.

The plug is a Numa 6-30 plug which has 3 connectors on it.



I have a bunch of 10-3 wire left over so I want to use it to wire the rest of the stuff, and I think that this is where I am experiencing the problem and confusion. From reading online it appears that most 240 wireing just uses 3 wires, 2 hots (black and white) and a ground. Since I am using a 10-3 cable, I actually have 4 cables inside (red, black, white, ground). What is the proper way to wire this plug. Should I still use black and red for the right and left connectection, or should I use black and white? For the ground connection I assume I use the ground cable? At any rate, it appears that one cable will be left disconnected, is that right? Should the one that is left be the white wire or the red wire? Also, I assume I have to loop through the ground in the outlet box before connecting to the plug (just like I would with 120v)? In the subpanel in the garage I have a dual braker for 240v and currecntly have it hooked up with 1 red and 1 black (these are the connections that are going to the plug as hot at the moment, with white being connected to neutral in the subpanel)

Okay, same question for the heater. Do I use black and white (both hot 120v) or can I use black and red connected to a dual braker (leaving white disconnected)

Sorry for the long post, just a little confused.

[sr20s14zenki]

It doesnt matter how you wire it with 230v, as long as you get the ground correct, atleast thats what im pretty sure my friend's cousin (journeyman electrician) told me. I run my welder on my plug, and have no issues at all with it. Im pretty sure mine is red, black, and green for ground, i would have to look to confirm.


I could be wrong about him saying that, but i didnt just guess, so i know i got it from somewhere.

[eblend]

I don't have a green in my cable, which is another concern, as the ground cable seems to be alot thinner then the other cables....and is no insulated. I assume that is okay, just seems strange. Is the green cable the same gauge as the red and black for you sr20s14zenki?

[sr20s14zenki]

Originally posted by eblend
I don't have a green in my cable, which is another concern, as the ground cable seems to be alot thinner then the other cables....and is no insulated. I assume that is okay, just seems strange. Is the green cable the same gauge as the red and black for you sr20s14zenki?

SORRY i just went and looked, yah, i have red, black, and ground (copper) and yes the ground is like half the size of the other two.

my bad

red and black dont matter which way, but ground is ground always.

[danno]

for the plug shown you don't need the white wire just put a marrette on it and leave it. the ground is almost always smaller don't worry it's normal.

[eblend]

Awesome, thanks guys!