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GFI outlet on knob & tube #180967
09/17/08 08:58 PM
09/17/08 08:58 PM
HCE727  Offline OP
Member
Joined: Nov 2005
Posts: 186
Delaware County, PA, USA
Years back I installed a GFI outlet in a bedroom that was wired in K&T. Every time I turned on the hallway 3-way, the GFI tripped. Has anyone ever had a problem with GFI's and K & T? After that I now install non-gounding outlets on K & T.


Hank
Work Gear for Electricians and the Trades
Re: GFI outlet on knob & tube [Re: HCE727] #180968
09/17/08 09:11 PM
09/17/08 09:11 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,301
Estero,Fl,usa
I bet you have a short to ground on a neutral. That could have gone on unnoticed forever. It could also be high resistance ground on a hot (petrified mouse or something.


Greg Fretwell
Re: GFI outlet on knob & tube [Re: gfretwell] #180971
09/17/08 09:38 PM
09/17/08 09:38 PM
T
twh  Offline
Member
Joined: Mar 2004
Posts: 947
Regina, Sask.
I put gfi protection on K&T fairly often.

Re: GFI outlet on knob & tube [Re: twh] #180978
09/17/08 10:33 PM
09/17/08 10:33 PM
E
EV607797  Offline
Member
Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
My guess would be that the far end of that three-way circuit (light fixture) is getting it's neutral from something other than the GFI's LOAD neutral output.

Basically, your hot LOAD output is feeding the point wire of the 3-way switch at one end, and the point wire at the other end is feeding the fixture. Problem is that the fixture is getting it's neutral elsewhere, even if it is on the same circuit ahead of the GFI.

Do you need to have the GFI protecting the circuit downstream form the device itself? It's a bit odd for K&T circuits to loop from device to device, but this does happen. Why not just put the in and out wiring on just the LINE terminals and be done with it?


---Ed---

"But the guy at Home Depot said it would work."
Re: GFI outlet on knob & tube [Re: EV607797] #181008
09/18/08 08:02 PM
09/18/08 08:02 PM
HCE727  Offline OP
Member
Joined: Nov 2005
Posts: 186
Delaware County, PA, USA
This happened to me years ago. There was only one hot and one neutral in the box that I installed the GFI in.


Hank

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