I have located the problem with a branch circuit in the panel fed by the 800 amp circuit breaker it is caused by the branch circuit powering a rooftop air handler it rained this morning the breaker tripped I megged it out and my result was the B phase wire had a reading of .096 MOhms
What test voltage?
.096Mohm is 96kOhm, which even at 277v, it would only let through 2.9mA (3/1000th of an A). Allow fluctuation for environmental variations and drop it to 1kOhm and you're still only pulling 300mA (which is just about the right current of a properly working 3 lamp fixture), it's not even remotely close to activating overload or shot circuit.
What test voltage?
.096Mohm is 96kOhm, which even at 277v, it would only let through 2.9mA (3/1000th of an A). Allow fluctuation for environmental variations and drop it to 1kOhm and you're still only pulling 300mA (which is just about the right current of a properly working 3 lamp fixture), it's not even remotely close to activating overload or shot circuit.