Disconnected Neutral

[gbeaumont]

Originally Posted by jpope

Great info. Thanks Marc.

Ditto Marc, thanks for the clarification, very well explained.

Regards

Gerry

[Bill Smith]

Excellent information, thanks Marc.

[Greg Fretwell]

There should also be some credit for Mr Ohm

[Marc D. Shunk]

Originally Posted by Greg Fretwell

There should also be some credit for Mr Ohm

That reminds me of this old electrician joke thing that you can draw on a napkin during lunch. What's this? :



It's a voltswagon pulling a mobile ohm.

[gbeaumont]

Originally Posted by Greg Fretwell

There should also be some credit for Mr Ohm

Funny Greg, I'll buy him a beer next time I run into him as well

Regards

Gerry

[Greg Fretwell]

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.

[John Allingham]

Another related article
http://ecmweb.com/grounding/electric...uth_grounding/

[George P. Wells, CMI]

Originally Posted by jpope

It's been a while since I've seen this condition, and I've always listed it as a "significant" defect. Can one of you remind me of the potential consequences of this condition?

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

[brian winkle]

Originally Posted by Marc D. Shunk

You're assuming way, way, way too much. Consider a rural property with no TV cable, no municipal water piping, and no natural gas service. This describes millions and millions of homes. The only "path", if you even want to call it that, is by way of the rod electrodes. No path at all, really, at the voltages we're talking about.

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.