I'm using a 5V relay to control wall AC socket to power up whatever AC appliance I could think of. But for the sake of testing I'm using 45W fan. For that purpose an AC/AC transformer (240VAC to 6VAC and later rectified and regulated to 5VDC) and wall socket are fed from the same mains socket.
The problem is that when the relays are engaged or disengaged it causes a voltage spike which can be heard through speakers attached to the same mains socket. What can I do to suppress these spikes, considering that in an extreme situation I might plug-in a 240VAC at 16A appliance going through the relay?