Safety is the number one priority on any job site. Sperry Instruments testing equipment can be put to good use ensuring that electrical equipment is properly installed and safe to operate. Faulty installations can be lethal, the condition of electrical installations can be established when contractors use test equipment. Any test unit that can be used to measure or review an application without coming in contact with a live conductor is a necessity. The IR thermometers allow for critical temperature measurements to be taken without having to touch an energized circuit. The D:S ratio or (distance to spot ratio), is a rating used to state the distance, in feet, that the test unit should be from the target in order to measure a one foot diameter section. In other words, a 12:1 D:S ratio means that from twelve feet away, the test unit is measuring a one foot diameter section of the target.