I've gone to a flat rate system a couple of months ago and charge $40.00 service call plus a $65 troubleshooting fee. Once the problem is found, the employees either look up the fix in the book or make a call to the office for a price.
We've only had one case where the problem could not be found in an hour. A homeowner had changed out a switch with a motion sensor and miswired the power such that walking by it would turn on several receptacles on the other side of the house, and then they'd time out and go off.
Anyhow, $65 is a little light for my employees and I'm thinking about some kind of graduated scale but not too sure about how to set it up.
Flat rate is the only way to go.
