Low voltage indicator lamp of 110vac circuit

No, the ground line is there for protection during fault conditions, not for general power supply connections.
Any indicator would need to go across the switched line and neutral.
There are low voltage, non-invasive circuits around, I believe one cropped up a couple of weeks ago.
Fairly simple arrangement from memory.
Others will know where to find it in the discussions here.
Basically worked by wrapping an insulated wire around the switch wire active.

 

You could put a current transformer at the switch driving a led, so indicating passing current. It may be possible to monitor the current and detect if the pump is stalled.
The only best way is to measure pressure.

 

Reference to #2, found the link.........

 

Five neon pilot lamps can be used,

Hot------------A-----------switch------------B-----------Pressureswitch---------C--------pump---------N eutral

A pilot lamp between A and N will tell the mains is good.
A pilot lamp between C and N will tell the pump is energized.
A pilot lamp between B and C will tell the pressure has been reached and pump is off.
A pilot lamp between A and B will tell the power switch is off and pump is enabled to run.
A pilot lamp between B and N will tell the pump is enabled.

Implement as many as you want, green, red,... wired, spade,...

 

I have the impression the Op wants to operate the indication remotely hence the original request for using the earth wire as one signal return.
Who knows as there has been no reply.

 

If you plan to run light gauge cable; cat3+ cable is cheap and could provide several conductors for signaling, even control a remote relay to turn the thing on/off from inside the house.
If the concern is running the well dry, a float switch in series could take care of that.

 

So you only wish to monitor that power is available to the pump via the isolator switch and NOT that the pump is actually running.???
So where is the switch and pump located in respect to eachother, where do you require the warning light to be and where is the power fed from??
Perhaps a pencil sketch of what is where and what you have in mind would be a great help.

 

So now the low voltage indicator is out.........

and you now want to by-pass the pressure switch ......

and have the pump manually run from 4 locations......???

Yes, can be done but not without running cabling ......

/or using some form of wireless control.

Depends on the size of the pump as to the size of the control relay/contactor/ or if you must, ssr relay.

You do know there are control relays that can detect either presence of water or pressure/lack of at start-up and operate the pump/or not depending on circumstances...would negate the requirement for all of these hack manual mods.

 

I use a 20K ohm resister and a LED between the switched line and neutral. Use a smaller resistor if LED too dim.

 

Normally, a pair of diodes in inverse parallel is used so that each diode protects the other ffrom excessive voltage.

 

Do yourself a favor and remove the pressure switch and replace it with a float switch.

 

Keep away from connecting to the ground wire. Already told you about that.
It's there for fault current conditions and connecting there can be dangerous.