I just learned something
I opened up the Sub Panel in my tool shed and noticed that there were separate bus bars for Neutral and Ground. I know the Main Panel has them bonded with a connector that runs behind the service terminals, and I wondered why the Sub Panel was not done the same way. So I looked it up and found this:
If you have the neutral and ground bonded at a subpanel, then you'll get neutral return current through the
ground wire back to the main panel (since there are now multiple paths). Even worse, as @Tester101 points
out, if the neutral ever has a fault, everything will continue to work but you'll have all the current on the ground,
which also means that you can now be electrocuted by touching the panel chassis, for example.
The ground and neutral must be bonded only at one place (in the main panel) to avoid this
I opened up the Sub Panel in my tool shed and noticed that there were separate bus bars for Neutral and Ground. I know the Main Panel has them bonded with a connector that runs behind the service terminals, and I wondered why the Sub Panel was not done the same way. So I looked it up and found this:
If you have the neutral and ground bonded at a subpanel, then you'll get neutral return current through the
ground wire back to the main panel (since there are now multiple paths). Even worse, as @Tester101 points
out, if the neutral ever has a fault, everything will continue to work but you'll have all the current on the ground,
which also means that you can now be electrocuted by touching the panel chassis, for example.
The ground and neutral must be bonded only at one place (in the main panel) to avoid this
