Originally Posted By: Bob Badger This post was automatically imported from our archived forum.
Good Catch Mike, I agree.
It looks like a green bonding screw in place near the bottom of the right side bar.
Also the tie bar is still in place at the bottom of the two bus bars.
I see what looks like a grounding conductor on the 5th terminal down on the left hand bus bar (just under the red 12 AWG)
So it looks like the right number of conductors have been run from the main to the sub 2 Hots, Neutral and Equipment Ground but are not isolated in the sub panel.
The green screw and the tie bar have to go away.
Blaine your post was not up when I started, but I saved the picture to my desk top and zoomed in to really check out the panel.
Originally Posted By: jpope This post was automatically imported from our archived forum.
Correct me if I’m wrong - The tie bar needs to be removed as mentioned, but then the ground bus needs to be bonded to the sub-panel. It looks like it’s isolated currently. Am I wrong?
Originally Posted By: Bob Badger This post was automatically imported from our archived forum.
jpope wrote:
the ground bus needs to be bonded to the sub-panel
Jeff I assume you mean the grounding bus (I know it is a pain but we want to be clear)
Then yes you are 100% correct and I should have said that, it totally slipped my mind. 
It looks like the green bonding screw can be removed from the grounded conductor bus and replaced in the grounding conductor bus.
The problem we have with it wired this way is a good deal of the neutral current will flow on the grounding conductor.
If the load is great enough we can have enough voltage drop on the grounding conductor to raise the potential of the metal enclosure above the potential of ground.
With these to panels this close it would be possible to put a hand on both enclosures and get a shock between them.
Your body would be trying to carry the difference in voltage caused by the voltage drop on the grounding conductor.
This is not likely to happen with the small load in the sub panel and the short length of run, but it could, this is one reason for the separation of neutral and grounding conductors.
It shows up much more in a heavily loaded sub panel farther from the bonding point, as I run into in commercial work.
Originally Posted By: Bob Badger This post was automatically imported from our archived forum.
rpalac wrote:
(In commercial loads you also can create a heat situation between panel grounding-grounded loads)
Thanks for the kind words and yes you are correct on the heating.
Going back to the panels pictured in this post if there was not a copper grounding conductor run between the main and the sub, the grounding would be accomplished through the metal pipe nipple connecting the panels.
This would be OK for grounding but as the neutral is bonded to the can a good deal of neutral current would flow through the metal nipple.
This would lead to heating of the pipe nipple and enclosure.
