|Non-Polarized plug and socket.|
Polarized power sockets are used in applications where interchanging the phase and the neutral conductors can result in shocks as in a toaster. Since the switch is connected to the phase line, send the phase supply through the neutral would mean that the appliance will have power even when it is switched off.
|Observe the difference in pin width|
A table lamp needs a polarized socket as interchanging the phase and the neutral lines would result in supply reaching the lamp holder even in the power off condition.