We run into Mr Ohm every day, the trick is recognizing it.
That was a good picture Marc posted, I tried to come up with an easy example for the terse answer I gave but it kept getting too complicated.
In the case of a lost neutral you have many loads on each side of the see saw and the ones on the high side will start blowing out, reducing the load and making imbalance worse … until everything on one side is blown open or on fire. Fortunately this doesn’t happen that often when you have a city wide metal piping system to take up the slack. As plastic replaces metal it will become more common tho. I suppose the real “fix” would be a shunt trip breaker that had a comparator between the 2 phases and the panel neutral bus and tripped the main if the difference went beyond a few volts.
I would say we don’t have the tombstone count to get this into the code but after some of the stuff I have seen rammed through in the last couple cycles, it wouldn’t surprise me.
Loss of Neutral is a major cause of electrical fires. When I do fire investigations (suspected to be electrical or I need to rule out electrical), that is one of the first things I look for.
If you sign up for our free electrical course “Inspecting Residential Electrical Systems - Advanced Topics and Concepts, Course 01”, you will get a detailed explanation of what happens. The course is approved for 4 InterNACHI or CMI continuing education hours. You can learn more about the free course here: http://www.bestinspectors.net/education/home.htm
My point was that the piping would become energized in r bradys example, as he presented a scenario with a furnace and a gas pipe. The current may or may not find a low enough path back to it’s source, as I suggested by stating there may be problems.