Fuse 3.00A 300W 50V PTC R4561A

Self resets when fault condition is removed. Hold Current is the maximum current at which the device will not trip at 20°C. Trip Current is the minimum current at which the device will always trip at 20°C.

Calculating Required Value
I = v(P/R), where I is the speaker input current, P is the speaker input power, and R is the speaker impedance. For a 80W per channel RMS amplifier driving an 8 ohm speaker, the speaker current is: I = v(80/8) = 3.2A, so the 3.7 A (trip current) polyswitch is selected.
Note: All quantities are supplied loose.

Spec Sheet