Abstract: An infrared sight glass for aftermarket fitment around an opening of an enclosure which enables thermal inspection of electrical equipment within the enclosure. The mounting of the sight glass is performed externally which avoids having to access the interior of the enclosure. The infrared sight glass comprises an infrared transmitting medium to facilitate use of an external infrared thermal imaging camera for monitoring the electrical equipment. A removable protective cover is locked into a closed position by security key screws and is easily removed by a slight twist when the key screws are loosened.