Choosing a Proper Amperage How to calculate for the Correct Relay

#### Relay Ratings and Limits

Relays often have two ratings: AC and DC.  These rating indicate how much power can be switched through the relays. This does not necessarily tell you what the limits of the relay are. For instance, a 5 Amp relay rated at 125VAC can also switch 2.5 Amps at 250VAC. Similarly, a 5 Amp relay rated at 24VDC can switch 2.5 Amps at 48VDC, or even 10 Amps at 12VDC.

#### Volts x Amps = Watts - Never Exceed Watts!

An easy way to determine the limit of a relay is to multiply the rated Volts times the rated Amps. This will give you the total watts a relay can switch.  Every relay will have two ratings: AC and DC.  You should determine the AC watts and the DC watts, and never exceed these ratings.

 AC Volts x AC Amps = AC Watts DC Volts x DC Amps = DC Watts Example: A 5 Amp Relay is Rated at 250 Volts AC.  5x250 = 1,250 AC Watts Example: A 5 Amp Relay is Rated at 24 Volts DC.  5x24 = 120 DC Watts If you are switching AC Devices, Make Sure the AC Watts of the Device you are Switching DOES NOT Exceed 1,250 when using a 5A Relay. If you are switching DC Devices, Make Sure the DC Watts of the Device you are Switching DOES NOT Exceed 120 when using a 5A Relay.