DIYbanter - View Single Post

Cydrome Leader

wrote:
"If it's not the same as the bulb
connected to hot and neutral, you have a faulty ground. "

Not necessarily. There is some voltage on neutrals in some places. This is caused by heavy loading on one side of the 240 compared to the other. It can be worse if common neutrals are used.

Saw one place that had like 20 volts on the neutral because of two 110 volt window AC units that happened to be on one side of the line.

Good point- there could be other serious problems with such a test.

But still, if you're in the US, have 20 volts on neutral relative to
ground, you probably have a bad neutral, which is also a big deal. This
problem could even exist outside your home, over at the distribution
transformer or wiring from there to your meter.

If your neutral "drifts" by 20 volts from ground, where it should be
bonded at the service entrance, and you have split phase 240 (120+120)
service you've got half the house with 100 volts at the oulets and other
side with 140 volts. That's not good for any devices or appliances you
have.