The invention is a light level monitoring and ATM control system which is designed for operation at a typical automated teller machine (ATM). The system is used to ensure that a user area associated with the ATM is maintained at a minimum light level. If the user area drops below a predetermined minimum, the preferred system disables the ATM and illuminates a warning sign to deter bank customers from approaching the area. The system does not directly measure the light level in the user area, but rather uniquely, indirectly determines the light level in the user area by measuring the output of a light fixture that illuminates the user area at a point remote to the user area and by calibrating the remote measurement relative to a measured value and a minimum value in the user area. The system, by indirectly determining the light level in the user area, does not suffer from apparent changes in light level in the user area due to the presence or absence of a customer or the color of a customer's clothing. The light sensors associated with the light fixtures may beneficially be hardwired and remotely powered, not battery powered, because of their proximity to the wiring plant associated with the ATM and the light fixtures.