A cooking stove with electricity and natural gas has been in place for 20 years. Last month I did deep frying, some of the oil went overboard, touched the electric plate, and some of it instantly vaporized into smoke. The oil also left a definite stain on the electric plate. Note that I didn't smell anything burned, and that the electric plate and cooktop was 1 meter from the power plug.
I didn't use the cooktop for a month and yesterday, when I turned on an oven daisy-chained to the same outlet, the house circuit breaker went off and I smelled something burned, which I then identified as burnt plastic. The outlet was burnt-out along with the electric plug of the cooktop:
(I found it hard to take a good picture because the burnt area is the blackest of the black.)
I did not find any residue of oil near the outlet. The cooktop has been in place for many years in an area by the seaside with much salt, humidity (up to 80%), so metal often corrodes and rusts.
Could cooking oil cause the outlet to arc and burn out? If not, what is the most likely cause?
Here is a photo of the house's electric panel. The tripped switch was third from the top left: