grounding old 2 wire junction to grounded junction
A separate ground wire retrofitted to an existing 2 wire circuit must go all the way to the panel where that circuit has its breaker. It doesn't have to follow the original cable exactly for example it could go through a hole in the siding to the outside and be somewhat hidden among the clapboards and then down to the first floor rim joist if it is too inconvenient to fish it through the walls and floors.
Exception: If the separate ground wire first reaches a fat ground wire from the panel to a water pipe or ground rod, it can stop there.
The jury is still out on whether a separately strung ground wire, if it should first reach another separately strung ground wire, for another part of the same branch circuit, it could stop there rather than parallel the latter down to the panel, although if I had to retrofit three somewhat adjacent receptacles on the same circuit with grounds, I would not run three separate ground wires all the way to the panel.
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Last edited by AllanJ; 03-28-2011 at 08:45 AM.