Do you have an example of how a cut off switch at the well head is setup?
I'm no electrician either but I do work around this type stuff all the time. Most wells will have either a pump house outside near the well head or the equipment is stationed somewhere inside or under your house. You could either have a deep well or the more traditional shallow type well. With the shallow well you will have a big old normally 3' round well curbing sticking out of the ground with a concrete top on it. In older homes it was normal to see some sort of wooden structure sitting next to the well curbing that housed the well pump expansion tank and fuse box. They most always had a light inside the structure and a plug of some kind to plug in some kind of heater to keep the equipment from freezing in the winter. This type setup was a pain because it always seemed like the light bulb that was placed inside the box to keep the water from freezing would always wait until it was -2 outside to blow out and let the water pump freeze up and you would have to go out in the middle of the night to thaw it out.
In newer homes they started making builders build the houses where they had more crawl space under them and this allowed all this equipment to be placed under the house rather than have a pump house out in the yard. This presented a problem as that if someone was working on or in the well they would have to pull the fuse or breaker in the main service panel and then go outside to do the work. The problem was that your wife comes home while you are in the well working and she discovers there is no water and sees the fuse or breaker tripped and puts in a new fuse or flips the breaker back on and lights up hubby in the well.
Like I said I'm no electrician and I'm not sure what the electrical code reads but it has always been a good working practice to install an electrical disconnect within sight of the equipment you are working on regardless of what it is, air compressor, well pump, AC unit, ect.
Personally I have never seen a disconnect switch at the well head other than the old type with the pump house. The disconnect is normally placed at the location of the equipment, expansion tank and pressure switch and then the wire goes out to the well where the pump motor is located. I'm not saying this is up to code but this is how most well systems are set up....at least around here anyway.
A disconnect switch is nothing more than a fuse or breaker between the motor and the service and could be installed at the well head by finding the feed wire before it goes into the casing and installing the switch in parallel to the line wiring at that point. You would have to mount it to a post or some other solid object at the location and would have to be a fixture rated for outside service. There are disconnect switches available that have GFI plugs incorporated within the enclosure but you still have to have 4 wires run to that point if the pump motor runs on 220/240 v.
This link talks about an AC disconnect switch but regardless of weather it's a AC unit or a well pump the principal is the same. Around the middle of the page it shows a disconnect switch that I like because it is the pull out type switch. I like these over a breaker type or fuse because I can pull out the plug and put it in my pocket while I work on the pump and it lessons the danger of someone flipping the switch accidentally and lighting me up while working.
Installing a 220VAC Circuit For Air Conditioning Condenser Unit — Knoji
