Tech school teacher was doing energy audits for power co. one system had been put in and customer conplained high power bills. he checked system and was running perfectly, no reason for hi bills.
few mo later he drove by and windows were open. found out they were taking care of mom. she didn't lie a/c, so would open up house after son left, and would close up and restart a/c hour before he came home. no one know what seh was doing until he happened to drive by in day.
Repeated no heat calls from a new install at a Starbucks. New programmable thermostat sub base shorted out every time. The various techs get there but no one can find the cause. This goes on for months. Sometimes problem once in 45 days. Sometimes problem two days in a row.
Get my handy meter out, turn off all the power and connect all the thermostat wires together, connect one lead connection to all the TStat wires and the other to the metal door frame as it represents a good ground. Sit there for maybe two hours as I watch the crews come in and out of the kitchen with the door swinging back and forth.
Getting tired of just sitting there watching the meter and an employee walks through the door and my meter jumps -- just a little.
Ends up the install crew ran the TStat wire behind the metal door frame 2X4's and when the metal door frame was installed they used very long self tapping screws that went far into the wall and sat next to the thermostat wire. With the right combination of a hard door swing and the wire swinging inside of the wall a short would occur.
Repaired the TStat wire and reran it in a different direction including tacking it down and never had a problem since.
"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis de Toqueville, 1835