As an electrical contractor in the 1970s and 1980s, I received intriguing phone calls from homeowners and commercial customers with strange electrical problems. I could troubleshoot some of these issues over the phone. Others required more time and investigation to determine the cause and origin. Most of the electrical problems could be figured out and fixed without major renovation, but some solutions would have required electrical-system rewiring. I am sure all experienced ECs have encountered some similar situations.
I had a phone call one day from a woman who said her home was haunted and that I needed to come out and fix it! I told her I didn’t handle that type of troubleshooting, but Ghostbusters could help her out. There was silence on the other end of the line, and then she said she was serious; it was not a crank call.
She said her refrigerator would not work until she turned her garbage disposal on. I told her that she probably had a multiwire branch circuit where the garbage disposal and the refrigerator shared a neutral, and the neutral had been lost somewhere in the system, thus putting the circuits in series rather than in parallel.
I asked her if any of her lights around the home were dim while others were very bright. She confirmed that was indeed occurring. She also stated that when she took a shower and stood on the metal drain connected to the cast iron drain line in the floor of the shower and adjusted the shower head, she received a major shock. That indicated to me that it was a utility company problem. I told her that she had a problem with the neutral at her service, and she should call the utility company since it sounded as if the problem was with more than the one multiwire branch circuit. She still wanted me to investigate, so I assured her that I would come out and examine the system. I found the underground power company neutral had been chewed apart by rodents and a good neutral connection by the utility company solved the problem. Case closed without calling Ghostbusters!
In another home, the lights would dim whenever a major electrical appliance would come online. A thorough investigation was necessary since the problem could have originated at the utility company supply and the location of the power supply. If the utility power supply was at the end of the distribution system with large loads on the system during summer or winter seasons, the voltage to the home may have been low during the peak season.
The first question to ask the homeowner was if the dimming problem happened during one part of the year or all four seasons. The next step was to install a current and voltage monitor at the service for a short period of time. The recording ammeter and voltage meter indicated that the voltage from the utility supply was low and resulted in a higher startup current for any motors located in the home, especially the air conditioning system during the summer. We called the utility company and it helped by adjusting the voltage at the service transformer. Care was taken to ensure the voltage was not adjusted too high, since that would cause a problem for the winter when the larger loads on the utility system were not present.
I n a third mysterious situation, a GFCI circuit in the bathroom kept tripping the GFCI outlet. I checked everything in the bathroom and could not make the GFCI trip. When I sat down at the dining room table to write out the paperwork for the visit, I turned on the dining room light and heard the GFCI trip. There were two separate circuits, one for the receptacles in the bathroom and the other for the dining room lighting, each with separate neutrals. The neutral for the dining room lights had been connected to the neutral side of the GFCI, causing an unbalance between the neutral and the hot conductor on the GFCI’s load side, which caused the GFCI to trip. The unbalance only occurred when the dining room light was turned on.
On a separate project, I heard about GFCIs tripping on several homes that were located near overhead 500,000V lines with enough induction to cause that to happen.
Each troubleshooting situation can be very different and unique, often requiring a good understanding of the basics of electricity and the operation of such systems.