The former owner of my house ran a subpanel off the main electrical panel to supply the attic when he finished it. I have several questions about it.
1. The ground wire from the main panel is attached to the neutral bar of the subpanel and all the grounds coming off the subpanel are attached to the neutral bar. Is this ok?
2. The neutral bar on the subpanel is corroded, and all the wires attached to it are basically frozen in. I cannot turn the screws to release the wires. Why would this happen? Is it ok to leave this as long as I am not needing to change anything?
3. If I do have to change something in this subpanel, can the neutral bar be removed and replaced, or do I have to replace the whole panel?
Thanks for the help.
Paul
Replies
I'd check to see if there's an aluminum wire involved.
You need to have 4 wire connection.
Two hots, neutral, and ground.
At the sub-panel you need to keep the neutral connections isolated from the ground connection.
Usually that means unbonding the neutral bus so that it is floating. In some case that mean removing a screw. In other is mean remove a jumper between the neutral bus and the ground bus.
In some cases you only have a neutral bus and then a separate ground bus is added.
Then only neutral wires go to the neutral bus.
And ground wires go to the ground bus.
With it being corroded you might need to cut all of the wires and replace the bus(es).
A picture will help.
Edited 11/20/2006 2:26 pm by BillHartmann
> Usually that means unbonding the neutral bus so that it is not floating.
"Floating" as I understand it from electronics means not connected to the electrical system. Hots, neutrals, and grounds should never be floating. If a light bulb burns out, and the switch to it is turned off, then the switch leg would be floating. If something measures zero volts to both hot and neutral with a low impedance meter, then it's floating. With a high impedance meter, you'll get some random number, but not more than the supply voltage.
I wonder if you're using the term "floating" in a different way?
-- J.S.
First I had it backwards. One of those nots that I keep forgeting found it's way in that sentence.It should be unbonding so that the neutral IS floating.Floating might not have been the best term to use. I was refering to that panel.The neutral bus in that planel is floating with respect to the case and ground bus.The neutral bus is bonded vai the neutral conductor in the feeder and that in turn is bonded back at the main disconnect.
Edited 11/20/2006 3:14 pm by BillHartmann