Bathroom wiring without ground and metal junction boxes. How safe?
#1
03-26-16, 04:05 PM
Bathroom wiring without ground and metal junction boxes. How safe?
I'm in the middle of bathroom remodel for a customer. The house is build in 1954 and wiring in the bathroom is old BX cable without bonding wire and all junction boxes are metal.
I am to install 2 wall lights and a bathroom fan/light combo.
I checked if junction boxes are grounded, but they are not. Measured 6 Mohms between neutral and the junction box. I know that metal sheathing of the cable without bonding wire cannot be used and ground conductor, but using metal junction box through out the circuit will naturally ground junction boxes. However, it appears someone rewired something wrong or metal sheathing have corroded or oxidized and caused break in ground (that is why bonding wire is required I guess.
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A previous electrician (or handyman?) installed recessed lights and a GFCI outlet but did not connect ground wire to anything. Just left it in the junction box. Funny how they connected a bare copper wire on GFCI and just left it in the junction box. Both light and GFCI outlets are on the same circuit, but lights are not GFCI protected.
All new wiring I pulled are wired with NM-B and bonded ground wire to the metal junction box.
My worry is that if wire insulation fails (very likely to happen since wires are old) or something fails in the light or fan, all metal junction boxes and metal sheathing may become hot.
Not too worried about the switches since I will be using plastic covers. But lights have large area of exposed metal and they are mounted pretty low (on the sides of medicine cabinet).
Is this situation still considered safe enough since it is old house?
Should I connect light circuit to load side of the GFCI outlet?
Because outlets for a bedroom next to the bathroom is taped from the switch junction box, they will be on GFCI as well if I do so.
I am to install 2 wall lights and a bathroom fan/light combo.
I checked if junction boxes are grounded, but they are not. Measured 6 Mohms between neutral and the junction box. I know that metal sheathing of the cable without bonding wire cannot be used and ground conductor, but using metal junction box through out the circuit will naturally ground junction boxes. However, it appears someone rewired something wrong or metal sheathing have corroded or oxidized and caused break in ground (that is why bonding wire is required I guess.
).A previous electrician (or handyman?) installed recessed lights and a GFCI outlet but did not connect ground wire to anything. Just left it in the junction box. Funny how they connected a bare copper wire on GFCI and just left it in the junction box. Both light and GFCI outlets are on the same circuit, but lights are not GFCI protected.
All new wiring I pulled are wired with NM-B and bonded ground wire to the metal junction box.
My worry is that if wire insulation fails (very likely to happen since wires are old) or something fails in the light or fan, all metal junction boxes and metal sheathing may become hot.
Not too worried about the switches since I will be using plastic covers. But lights have large area of exposed metal and they are mounted pretty low (on the sides of medicine cabinet).
Is this situation still considered safe enough since it is old house?
Should I connect light circuit to load side of the GFCI outlet?
Because outlets for a bedroom next to the bathroom is taped from the switch junction box, they will be on GFCI as well if I do so.
#2
03-26-16, 04:26 PM
Group Moderator
If you pulled in new wiring with the NM-b the boxes should be properly grounded to the ground of the NM cable.
Insulation very rarely fails inside an older cable/conduit, most cases it is in junction boxes where people have over lamped light fixtures.
Code only requires GFCI protecting the receptacle(s) in the bathroom. Since there is no ground path in the old BX a GFCI would not trip if the cable jacket were to become energized unless some other path to ground was available.
If you have made modification to the existing wiring, and that wiring serves locations required by the 2014 NEC to be AFCI protected, an AFCI device/breaker is required. IE: If the lighting circuit serves other locations in the house like the bedroom you mentioned.
Insulation very rarely fails inside an older cable/conduit, most cases it is in junction boxes where people have over lamped light fixtures.
Code only requires GFCI protecting the receptacle(s) in the bathroom. Since there is no ground path in the old BX a GFCI would not trip if the cable jacket were to become energized unless some other path to ground was available.
If you have made modification to the existing wiring, and that wiring serves locations required by the 2014 NEC to be AFCI protected, an AFCI device/breaker is required. IE: If the lighting circuit serves other locations in the house like the bedroom you mentioned.
#3
03-26-16, 05:00 PM
If you pulled in new wiring with the NM-b the boxes should be properly grounded to the ground of the NM cable.
What I was wondering is should I GFCI protect lights as well since there is no ground. It would trip if someone touches housing that has become hot. Does NEC consider ungrounded light safe?
The job is in Montgomery County, MD. And I just checked which NEC they follow. They are still on 2008. So, I guess AFCI is not required.
.If if it did, I'm sure the home owner will not be willing to do that and probably fire me for finding issues. LOL
I already got yelled at for finding circuit not grounded.
#4
03-26-16, 05:20 PM
Group Moderator
However, it appears someone rewired something wrong or metal sheathing have corroded or oxidized and caused break in ground (that is why bonding wire is required I guess. 
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The code dictates when GFI protection MUST be used. You can use GFI protection in any place you choose.
