I"m installling a 220V circuit in mine attached garage. The circuit will power an older waiting compressor which has a 3 prong plug. Ns have currently pulled a 10g 10/3 cable and mounted in a receptical box. I provided 10g since the run is around 90 feet and the waiting compressor is rated at 20 amps. There was a graph in home Depot that recommended 10g. Ns purchased a three prong receptical to enhance the plug.I"m searching for confirmation top top my following steps. I should cap the white wire on both ends because it will not be in use. The black goes in one side of the twin gang breaker and also the red walk in the other. The floor attaches favor a soil on a 110v circuit. I"m going to the library to watch if i can find a good book to be extra safe, however was spring for specific feedback. Thanks in advance.

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Yes jus t lid the white at both ends don"t reduced it, you may need that later.The ground will certainly go to the box & to the the facility prong on the receptacle.

As you more than likely realize, you do not require the neutral wire (white) for this device. However, at some point it may be needed. Leaving it the same length as ath various other wires and simply place a cable nu end the end. Tuck it out of the method in the panel and in the outlet box.
Great. Say thanks to you both very much. One added question if ns may. I checked out the library this afternoon and also was reading around the code readjust in 1996. I don"t completely understand it, yet it appeared to indicate that the floor in a 10/2 is transferring some lot of current back to the panel and not simply to pilgrimage the breaker. The 10/3 add to the white to return the circuit and the soil is used simply to pilgrimage the circuit-breaker. Again, I probably screwed the explanation up, however here is my question: have to I investigate even if it is I can update my compressor to usage a four prong plug? Or am ns OK through the 3 prong and capping the white wire on both ends?Again, thanks.
Originally posted by gregwils Great. Thank you both really much. One added question if ns may. I checked out the library this afternoon and also was reading around the code change in 1996. Ns don"t totally understand it, however it seemed to suggest that the floor in a 10/2 is moving some lot of current earlier to the panel and not simply to trip the breaker. The 10/3 add to the white to return the circuit and also the soil is used just to expedition the circuit-breaker. Again, I most likely screwed the explanation up, but here is my question: should I investigate whether I can update mine compressor to use a 4 prong plug? Or am i OK with the three prong and also capping the white cable on both ends?Again, thanks.

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The readjust I suspect you are referring come is because that ranges and dryer circuits. What is unique about those is that they have 120 volt loads and also 240 volt loads in the very same appliance. That means that over there is a current flowing top top the neutral during normal operation. For plenty of years the us NEC allowed the bonding that the metal framework such appliances to the neutral rather than request a separate devices Grounding Conductor. Due to the fact that your compressor is only a 240 volt fill there is no ar to affix a neutral come it so there is no for sure conversion that you can undertake. --Tom H
As hornet has actually mentioned, the is dryers and ranges that supplied to be 3 wire and are now four wire. Dryers and also ranges typically have some 110 volt components, such as lights, clocks, timers, buzzers, etc. These portions of the applicance usage 110 volts and need a route for the return current. Directly 220 volts is supplied for the big job that these appliances perform, heating, and also does not need a return, together the return is via the other half of the 220 line.

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