Relay HAT External Power Use

Hi there. I got Relay HAT for Raspberry Pi. There is a power selector on the board. In which cases should I use an external power supply for the relays?
PS. I’m using Raspberry Pi 3.

Hi Kelsey.
Relay HAT uses 5V power output of the Raspberry Pi.
Raspberry Pi supplies enough energy for all of the relays. But if you have power hungry devices connected to the USB ports, we recommend using an external power supply.

@kelsey Be sure to use a reliable power adapter, preferably Raspberry Pi’s original power supply. It should supply 5V 2A for long-term stable operations.

Thanks guys, I have the original power adapter, the white one.