6) Can I use a bare ground to power the coil on 120V starter?
The short answer is no. Will it work? Yes.
A lot of folks will order a starter for 230V and request an operating voltage of 120V. Now this is fine but we usually follow up by asking if they are going to pull in a neutral to operate the coil… Sometimes the answer is, I will use the ground… So what they are saying is they are pulling in 3 hots and a mechanical ground. By using one leg (exception high leg delta power) if you reference from one hot to ground you get 120V. The problem is that the mechanical bare ground becomes a current carrying circuit. Sometimes customer's will respond, well the neutrals and bare grounds are tied together in my panel.
Briefly, in a 230V circuit, the current is traveling between hot and hot and hot (3 phase) - your reference is phase to phase since all phases are opposite at any point in time. When you ground your distribution panel and tie your neutral wires to the ground bar - the ground rod is not a passing current. But at the point where power is applied any wiring leaving the ground bar (neutral) becomes a current carrying conductor. If you were to verify this with a clamp meter you would read zero Current in the ground conductor between the ground rod and the distribution panel. Then, reading the Current on any neutral wire connected to the ground bar would read that circuits Current. Remember, Current is the same in a series circuit from start to finish.
In our example of using a bare mechanical ground as a neutral to power the coil of a starter, yes, it will work. However, the same Current carried through the hot wire is returned on the ground wire… Current being current it will travel the path of least resistance so hazardous shock is not likely (unless a person is grounded very well). But if that circuit becomes broken or open at some point, then you could become the ONLY path to ground. This would make your circuit a floating neutral looking for a way to ground out.
