On Tue, 3 Mar 2020 20:14:01 +0000, Skyhawk
m wrote:

Have had the same set up for the past three years with no changes or issues.
240 v unit, 30 amp breaker. Twice in three days the heater has sparked and
tripped the breaker. Open the cover and everything is hooked up but one
connection, supply side of the thermostat, has evidence of arching. Cut the
burned wire nut off, stripped the wires and reconnected. Two days later it
happens again. Still a loose connection or other possibilities?

I bet the bottom element is covered in sediment and burned out.
Disconnect it to verify. (both sides) Wirenut the bare wires before
you power back on.
If so, it is water heater time.,