Hi all - first post here. Long time fan of TOH. I'm pretty comfortable with most home remodel tasks. Started finishing a basement in our 1920's home that was rebuilt 5 years ago due to a total loss fire (before we owned). Most of the wiring for the house and alarm was surface mounted in the basement so my firs step has been to relocate that up into the joists. All went well and was finishing up tonight installing a new wire to the cold water pipe. Here's where things got tricky.
The system has two GECs - one to a ground rod outside the panel at the back of the house. The second (which is technically the primary according to code?) runs to the front of the house and conencts to the copper pipe where it enters the basement. This conductor is spliced with a split bolt. I had to lenghten it when I relocated it.
Figuring that I already had one ground (to the pin outside the panel) I did not bother to shut the power down at the service entrance. When I disconnected the splice the lights in the house dimmed a bit. Odd. I ran the new wire and when I reached up to connect the splice - ZAP..not huge but a shock and a small spark when the wires were connected together. I then shut the panel down and connected, re-engergized and all seems fine. Please don't respond that the panel should have been off - I need help figuring out where I'm getting current on the GEC. Now when I touch the GEC - no shock...all seems fine.
Any thoughts how I am getting current on this wire? How can I measure it? How can I find the source? Is it possible that the water pipes themselves are being electrified by another home on the street? We live in a row home in Baltimore - our place is nicely fixed up but there are some on the street that are probably original.
Appreciate your help!