Squard D QO-20M panel - use as subpanel - isolate neutral

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Old 10-19-12, 08:07 PM
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Squard D QO-20M panel - use as subpanel - isolate neutral

Have an old QO-20M panel in my external garage wired up as a subpanel. Previous owner did not have it hooked up correctly, they had all the neutrals and grounds all connected to the one and only neutral/ground bar. I pulled new 100A service to the garage and want to wire this panel up correctly. I do not see a bonding screw on the neutral/ground bar. Seems to be a popular panel but I cannot find any documentation on it. Just wondering if anyone knows if I can isolate the neutral on this panel and add a seperate dedicated ground bar or should I just scrap the old panel and buy a new one?
 
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Old 10-19-12, 08:23 PM
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I don't know that panel without seeing it. Sometimes the neutral bonding screw masquerades as a ground screw. Which means that one of the screws in that neutral bar may go all the way thru to panel. That bar may also be permanently bonded to panel just by its design in which case you would have to add an isolated neutral bar and the existing one would become your grounding bar. You have all the breakers, the panels themselves are pretty inexpensive to replace.
 
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Old 10-19-12, 08:40 PM
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Remove the bond screw and install a ground bar. I forget the model number off the top of my head.
 
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Old 10-19-12, 09:20 PM
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Use a continuity tester between the bar and the panel. In the end, if there's continuity (0 ohms) you can't use it as your neutral.
 
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Old 10-20-12, 07:14 AM
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If you can't identify the bonding screw, try looking at the back of the panel, the bonding screw will be screwed into a hole with tapped threads and can be seen from the back. You'll have to distinguish the mounting screws from the bonding screw, but that should be obvious.
 
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Old 10-20-12, 06:14 PM
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If you use a multimeter touch it between the neutral bar and the panel to check for continuity. If there is no bonding screw then it may have already been removed. If there is no continuity then you just have to screw a new ground bar onto the panel and seperate all the neutrals and grounds. Pics would help
 
  #7  
Old 10-20-12, 11:02 PM
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Problem is resolved. The neutral/ground bar is isolated. Apparently one of the bare copper wire grounds in the romex was grounding out in the panel case. I am going to be re-wiring the entire panel.
 
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Old 10-21-12, 11:08 PM
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Glad you got it figured out, and thanks for letting us know.
 
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