paul renshaw
Senior Member
- Location
- Cordova, Maryland
Good afternoon,
This is something I felt that I should share with you guys. The attached photo is from a transformer in our facility that feeds the outside lighting, and just shows how important proper grounding and bonding is. We had erratic voltage and an energized pole on our system because of a short circuit and the lack of a low impedance fault current return path. The guys came to me scratching their heads, so I went to help investigate. As you can see in the photo, two lugs bolted side by side showed infinity ohms on the meter, sounds impossible right? When you metered between the two lugs while energized, there was 120 volts between them due to the lack of continuity (bonding) to XO of the transformer. They were bolted through the transformer slots and not to a bus bar or tapped to the frame, and the paint was never cleaned off, as required by code. I'm not sure who did this work, but we are going to be checking other transformers in that building also.
This is something I felt that I should share with you guys. The attached photo is from a transformer in our facility that feeds the outside lighting, and just shows how important proper grounding and bonding is. We had erratic voltage and an energized pole on our system because of a short circuit and the lack of a low impedance fault current return path. The guys came to me scratching their heads, so I went to help investigate. As you can see in the photo, two lugs bolted side by side showed infinity ohms on the meter, sounds impossible right? When you metered between the two lugs while energized, there was 120 volts between them due to the lack of continuity (bonding) to XO of the transformer. They were bolted through the transformer slots and not to a bus bar or tapped to the frame, and the paint was never cleaned off, as required by code. I'm not sure who did this work, but we are going to be checking other transformers in that building also.
