I will try is this issue is possible to fix by ignoring single overamp ticks. That shoud be relatively easy to implement.
Basic idea: Every cable gets a variable. One tick overamp rises it by 100, Every tick without lowers it by one. Rises the variable above 400 the cable melts. In case it is just 1-2 ticks on chunkload that melts the cables, this should help without breaking the general function.
... or just disable getBaseMetaTileEntity().setToFire() until first onPostTick().