The light draws 150 watts on a 120-volt circuit.

I = 150 watts ÷ 120 volts
I = 1.25 amperes

The light uses 1.25 amperes of electricity. The heater draws 3600 watts on a 120-volt circuit.

I = 3600 watts ÷ 120 volts
I = 30 amperes

The hair dryer draws 1800 watts on a 12-volt circuit.

I = 1800 watts ÷ 120 volts
I = 15 amperes

The total number of amperes on your circuit is 15 + 30 + 1.25 = 46.25 amperes. This overloaded your system and stopped current from flowing to the circuits. If the overload did not happen you could have started a fire.