My power comes from a line that is about 2000 feet long and my drop comes from about the middle. It is just two wires, hot up high and the neutral lower. About a month ago one of my trees took out the neutral before my drop. Nevertheless I still had power. What gives? Eric
The neutral wire is grounded at the power utility transformer, typically at the pole on which the transformer is mounted. At your house, the neutral wire from the transformer is connected to the neutral bus in your circuit breaker/fuse panel. Inside that panel there is a connection between the neutral bus and the ground bus. That connection is required by the NEC (National Electrical Code). The ground bus is also required to be connected to the "electrode grounding system" - typically referred to by homeowners as the "ground rod". So with a broken neutral wire you still have a complete circuit from hot to the panel by the unbroken wire, and from neutral at the transformer to ground, through the ground to your "grounding electrode system" which is connected inside your service panel to the ground AND the neutral bus.
The top wire is 17,000 volts. The lower is the neutral. Both are tied to a transformer that feeds my house and one across the street. The neutral is also tied to a ground at the pole. There is at least one pole before mine that has a wire going to ground from the neutral. And yes, I did have 220 while the neutral wire was down. I am amazed that the ground could work so well. Maybe it's because the ground here is so wet. Eric
That's pretty scary, actually. If the ground at the pole was broken, or marginal, the primary would be grounded by your & your neighbor's service ground rods. I.e., your service would be part of the 17,000 volt circuit. In the very worst case, if your grounds were broken, you would have 17,000 volts on your houses' circuits, just waiting for a path to ground.
Part of it working so well is that most of the current in one leg returns through the other leg. It's only the difference that returns through the ground. E.g., if there were 10 amps of load on 1 leg and 12 on the other, only 2 amps would flow through the ground.
When I first saw the line down I was leaving my place. I saw a cable on the ground and thought it was a stay that broke. But then I looked up and could see the neutral was broken, not a cable stay. When I called PSE I told them I had a neutral line down. They told me to treat it as if it was a live wire. I then said "Does that mean I shouldn't lick my finger and touch it?". The woman I was talking to just got silent for a couple beats and then repeated her admonition. Eric