The SF90SVIT is a Low voltage surface mounted centrifugal fan with timer. As an alternative to the standard AC version the low voltage 24v model provides an additional level of safety for operation in a moist or wet environment. Safety Extra Low Voltage (SELV) fans have been designed for increased safety when installing fans within a bath or shower spray area. SELV fans have an isolating transformer(which is located in an area away from the fan) and reduce the voltage to 24v so that in the unlikely event of a fan fault the electrical charge is at a safe level. SELV fans are the safest option for use in 'wet' areas offering increased peace of mind and have a safety rating of IP57 and can be located in Zones 1, 2 or Outside.