[AMRadio] 220 vac line

[Gary Schafer]

Neutral must be grounded to earth at some place in your power distribution,
usually at the service entrance panel.
 
The SAFETY ground wire (bare or green) must also be bonded to the neutral
somewhere in the system, usually at the service entrance panel.

If the hot wire should touch/short to the chassis the safety ground wire
becomes the return path for the current back to the neutral at the service
panel to ensure that the breaker will trip. 

The EARTH ground rod(s) are bonded to the neutral and safety ground wire.
Earth ground is not there to trip the breaker in case of a fault. Earth
ground is there for a lightning path and to prevent stray currents on
equipment.

73
Gary  K4FMX

 
>  Regarding the neutral, remember that is the wire that runs to the
> centertap
> on the 240 volt secondary service, that must be a solid connection to
> maintain the 120 each side of the line. The ground may or may not be
> connected to the neutral and is almost never a good ( low impedance)
> ground.
> The typical 8 ft ground rod is simply terrible, frequently 20 Ohms or
> so. If
> 120 goes to the
> "grounded" chassis it simply flows 6 Ampers or so to ground and the
> chassis
> would be at 120 volts.
>  My ground circuit here is eight 8 ft rods under and spread around  the
> footer all bussed together with #4 Cu, another #4 goes to the big ground
> rod, 5 inch pipe 180 feet deep.  measures about one Ohm. The main panel
> has
> a big fat MOV block on the secondary side of a 60 Ampere breaker.