I have a main panel that was converted to a sub panel when a new Main Panel was placed in a new addition to the house. So now, the subpanel appears to have two grounding wires connected along with the neutrals on the bus bar (middle right). The fat bare wire on the left is the Main Panel grounding wire that is not being used. Most of the grounding wires, in the subpanel appear to be grounded down the wall cavity to a copper pipe in the crawl space. All the outlets show a correct installation with a receptacle tester.
???Can this type of incorrect installation (ground to neutral bar) cause the following???:
I've lived in the house for two years now. Recently, the living room lights have started to flicker once in a while. The power will shut off for about 1/2 second. This might happen 2-3 times before shutting off completely. No breakers get thrown. After 1-10 minutes or so, of me doing nothing, the power comes back on. These symptoms are now more and more reoccurring. This occurs even with nothing turned on except a surge protector, modem, and router. Maybe the breaker is bad and the grounding to the neutral bus bar is incorrect?
I plan to replace the subpanel (use modern parts), use a insulated neutral bus bar, a separate grounded-to-the box grounding bar that will ground to a copper pipe in the crawlspace. I'm not sure if I should connect the bare ground wire from the Main Panel to the grounding bar in the subpanel? The subpanel and main panel are in the same house and are about 20 feet away (20' wire travel).
Best Answer
1) Replacing the subpanel is a very good idea -- FPE Stab-Loks are absolute junk that have a well-known propensity for failing to do their job when called upon, and also are susceptible to faults in the busbar-to-breaker contacts (high resistance/overheating) that are documented to cause the symptoms you're seeing -- this phenomenon can develop into a full-fledged electrical fire!
If a complete replacement of the subpanel is impractical for whatever reason, there is also the option of gutting the box and using one of the Eaton CH retrofit kits to replace the innards. Since your box is a mere, oh, 7" wide by 11" tall, this requires an Eaton RWCH6L125N retrofit interior, the matching cover (a CRWCH6ML of the appropriate size), and the appropriate Eaton CH breakers (it looks like you can use a CH220 and a CH250 along with a pair of CHT1515s, but I'd need to know more about what this subpanel feeds in order to specify for certain).
2) You will need to run a ground wire from the subpanel to the main panel, and separate the ground and neutral bars in the subpanel; however, you do not need a GEC + grounding electrode for a subpanel in the same building as the main panel, as such an installation falls under NEC 215.6: