Is it fine for switch rated for 3A to conduct current which continually peaks to 8amps but is below 3amps RMS limit?

 

Kinda depends.....how long can you hold finger in flame? Most can for a short while......but not very long.

What does continuous peaks mean? Can you flicker your finger thru a flame?

Your answer is maybe. But not good practice. Keep finger out of flame.

 

I guess the switch would breakdown because of the heating effect at the points of contact ...

This is dependent on the square of the current .... three squared is 9 ..... eight squared is 64 .... so an eight amp current will heat SEVEN times more than a three amp current , but your'e not passing 8 amps for the whole cycle ... you have to work it out depending on the shape of the current curve.

 

I read it as 3 amps at 125 VAC....or 3 amps at 28 VDC. With a resistive load.