I had a friend wire 10-3 line for a new heat pump. He connected the red and black conductor wires in the house to the 2-pole 60 amp breaker and the neutral white to the neutral bus bar. The outdoor disconnect box (pictured) has terminals for 2 conductor loads, a terminal that the neutral ends at neutral. The heat pump condensing unit only has 3 terminals (L1, L2, GRD).
My question is: why don't I have to run the neutral to the unit? Should I disconnect it from this terminal and breaker neutral bus bar? My friend said I can land the ground to it but didn't explain why. Thank you for your help in this matter.
Best Answer
Neutral is not ground
That thing you are calling a "neutral bar" is bolted directly to the steel of the switch box. It cannot be a neutral, it must be a ground.
Neutral is an active, live conductor that carries current under normal conditions. It is normal for it to have "voltage drop", or more accurately "voltage rise". Ground is a safety shield, and should never flow current except during fault conditions.
In your installation, your appliance does not use neutral. Cap the wire off (Put a wire-nut on it) and wrap the nut with tape because they love to fall off single wires. The stud you have neutral on, is for ground. A neutral bar would be insulated from chassis, since we are anywhere but the main panel.
Conflating/interchanging neutral and ground defeats the purpose of running grounds. People tend to get misled by a couple of things.