When should a signal relay be used instead of a power relay? Power relays are designed to switch power, and signal relays are designed to able to switch minute signals due to their contact design having very high reliability. These special contacts allow signal relays to have a much smaller minimum permissible load; For example, the minimum permissible load of a G2RL power relay is 24 VDC at 40 mA whilst the signal relay G6K is 10 mVDC at 10 μA.  Another feature of signal relays is their low coil power consumption. On a power relay, typical coil power consumption is 400 mW while for a signal relay it is a mere 100 mW. Lastly, there is a big difference in size. Signal relays are ultra-miniature, occupying very little space on the PCB when compared to power relays.