We don't recommend running a 12 Volt or 24 Volt fan via your power outlet. One of the main reasons for that is the lack of a universal standard for 12V and 24V power supplies, whereas there is a USB standard. This means that you potentially need several adaptors to be able to connect fans properly to the power supply. Therefore, we would recommend using a 5V fan instead of a 12V or 24V fan, and following the description below.

To power our 5V fans using a regular power outlet, you will need a customary USB power supply or power bank (or any other 5V DC power source with a USB port, such as laptops etc.).
We include an NA-AC7 USB power cable with some 5V fans, and you will only need an additional power supply to power one of these fans via USB. Please check the fan's scope of delivery to verify that a USB cable is included. 

When powering a 5V fan via USB, the fan will run at maximum speed, and it will not be possible to adjust the fan speed.
If you would like to adjust the fan speed, we would recommend combining a 5V PWM fan with an NA-FC1 fan controller. (Please ensure that you have selected a PWM fan model, as non-PWM fans cannot be controlled with the NA-FC1.) This way, you can take advantage of the fan's full RPM range by adjusting the knob on the controller. The setup is very straight-forward: To enable speed control, simply connect the NA-FC1 between the fan(s) and your power source.

USB 5V PWM fans with NA-AC7:

200mm: NF-A20 5V PWM 

140mm: NF-A14 5V PWM

120mm: NF-A12x25 5V PWM, NF-F12 5V PWM

92mm: NF-A9 5V PWM

80mm: NF-A8 5V PWM

40mm: NF-A4x10 5V PWM