In a circuit, a resettable fuse (or polyswitch or PPTC) is a kind of breaker component that trips when the AMPERAGE exceeds a given treshold to protect against overcurrent faults. PPTC basically trips because of heat dissipated by high current which makes its inner connection loose and opens the circuit.
The question is: If heat dissipation can be calculated using watts (amperage X volts = watts), then how can this PPTC be rated at exactly 4000mA while being suitable for between 16v and 240v? 4A*16V=64W up to 4A*240V=960W. That's 15x the power. Have you ever touched a 40W vs 100W light bulb? It's not the same heat dissipation at all. So how can this be that the same PPTC will trip at 4A no matter if the circuit is under a 16V or 240V tension?