Old 03-27-08, 07:19 PM
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Why does a 240 30,40, 50 etc amp breaker use 3 wire + gnd and a 240 15 amp breaker use 2 wires + gnd? Is it the amperage, the devices being plugged in?
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Old 03-27-08, 08:07 PM
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A 240 volt breaker use only two wires. Whether the circuit use two or three wires depends on the load requirements.
A 240 volt motor only needs two wires.
A 240 volt piece of machinery that has control circuits might need a 240/120 volt supply.
Old 03-27-08, 08:20 PM
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A 240v c/b feeding a sub-panel generally (but not always) has two hots, a neutral and a ground. If you desire, require 120v power as well as 240v, that is.

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