Problem: 15A single-pole breaker in panel randomly trips - has been doing so since buying house in 2009 (house built in 1987)
Trouble shooting steps: I have an outdoor power outlet and two bathroom power outlets that do not appear to be GFCI. The outlets do not have Test/Reset buttons- there's no labeling for GFCI anywhere.
I bought a $10 GFCI Tester. (Those little three-pronged things with 2 yellow/1 red light and a "GFCI test" button)
When I insert the GFCI tester into the any of 3 known outlets on the circuit (2 bathroom outlets, 1 outdoor outlet) and push the button on the tester, the 15A breaker in the panel flips, killing power to all 3 outlets and the hall lights. Far as I can tell these are the only connections on that 15A breaker. Worth noting(?) this 15A breaker that keeps tripping is the only one in the panel with a test button.
When I insert the GFCI tester into other non-GFCI outlets in the house and push the button, nothing happens - outlet remains hot and the connected source breaker in the panel does not flip.
I have replaced all 3 outlets myself since moving in, but this overall problem persisted prior to me replacing the 3 outlets (2 bathroom, 1 outdoor) - and has persisted since outlet replacement. Breaker randomly flips, often when the A/C kicks on or is running (not on same circuit, per the breaker panel) or the pool filter is running (connecting to outdoor outlet in question) or a hair dryer is used in one of the 2 bathroom outlets in question. Sometimes the vacuum running in the living room will flip it, despite those other outlets apparently not being connected to the 3 outlets on the circuit in question.
Looking for some guidance on what this means. I've since read on this site that these cheap GFCI testers are not really good for old wiring troubleshooting, but I didn't know that prior to purchasing one. I would like to spare the expense of an electrician, if I can. My next thought is to replace all 3 outlets with GFCI outlets and see if that resolves this. Or maybe replace the 15A breaker itself, except that I assume it's doing what it's supposed to do - trip when there's a problem on the circuit.
Thanks in advance.