JHZR2
Staff member
Living in an older home, we have a few circuits that are ungrounded. We did a pretty thorough rewiring a few years back to remove most knob and tube, but there still are a few lights and things that are fed with it, it's all in fine shape, and those circuits we put on AFCI breakers for added protection. The load on them is really light.
But I happened upon one instance where I was curious..., in reading it is recommended that gfci outlets be used on ungrounded receptacles to add a layer of protection. We have one receptacle on the upstairs knob and tube circuit, and it then feeds a vent fan in the bathroom that was installed in the 70s or early 80s, I think. It is fed through a gfci.
But the installer connected the ground conductor on the Romex that goes out from the circuit to the fan and it's switch loop. So there is a ground conductive path from the outlet that power is pulled from, to the fan to the switch loop. Of course it ends at the gfci and does not continue back to the electric panel or an earthen ground.
I've seen discussion for gfci outlets being used in ungrounded applications, that the ground wires on subsequent outlets should not be connected. However, for a hardwired load (fan) or a switch, is there a reason why it perhaps should be connected? My understanding is that a gfci looks for an imbalance in the hot and neutral lines, and it may not necessarily monitor the presence of voltage or any other indicator on the ground connector itself. That's part of the reason why they are preferred for two-wire ungrounded applications. But does a gfci look at the grounding wire at all? Notionally in a fault, it could have 120v potential to neutral, which I suppose is what the gfci could be watching for, and a reason to connect them though they don't actually "earth" any current.
Everything that I've seen appears to have been done properly to code at the time, and all the work is good quality. However I think the connection of the ground was a mistake. That said, everything I've seen that indicates that grounds shouldn't be connected is related to receptacles, not switches or hardwired loads, is there a scenario where it makes sense to connect the ground wire locally on an ungrounded circuit! because of how the gfci functions?
But I happened upon one instance where I was curious..., in reading it is recommended that gfci outlets be used on ungrounded receptacles to add a layer of protection. We have one receptacle on the upstairs knob and tube circuit, and it then feeds a vent fan in the bathroom that was installed in the 70s or early 80s, I think. It is fed through a gfci.
But the installer connected the ground conductor on the Romex that goes out from the circuit to the fan and it's switch loop. So there is a ground conductive path from the outlet that power is pulled from, to the fan to the switch loop. Of course it ends at the gfci and does not continue back to the electric panel or an earthen ground.
I've seen discussion for gfci outlets being used in ungrounded applications, that the ground wires on subsequent outlets should not be connected. However, for a hardwired load (fan) or a switch, is there a reason why it perhaps should be connected? My understanding is that a gfci looks for an imbalance in the hot and neutral lines, and it may not necessarily monitor the presence of voltage or any other indicator on the ground connector itself. That's part of the reason why they are preferred for two-wire ungrounded applications. But does a gfci look at the grounding wire at all? Notionally in a fault, it could have 120v potential to neutral, which I suppose is what the gfci could be watching for, and a reason to connect them though they don't actually "earth" any current.
Everything that I've seen appears to have been done properly to code at the time, and all the work is good quality. However I think the connection of the ground was a mistake. That said, everything I've seen that indicates that grounds shouldn't be connected is related to receptacles, not switches or hardwired loads, is there a scenario where it makes sense to connect the ground wire locally on an ungrounded circuit! because of how the gfci functions?
