Ultrasound Testing


While infrared thermography will detect heat generated by arcing and in most instances tracking, it will not sense corona. An integrated approach incorporating infrared and ultrasound is recommended for the detection of the potential of arc flash. You will be able to hear any arcing long before it starts to cause heat buildup, thus allowing you to fix potential problems at their early stages and before damage occurs.

In order to use infrared properly, you must remove the covers to do your scanning. A potential Arc Flash condition could exist and by using ultrasound before removing the cover, you can detect the danger before putting personnel in harm’s way.


The main concern in low-voltage equipment is arcing. Typically, 110-, 220- and 440-volt systems are inspected with infrared imaging for temperature changes. Hot spots, usually an indication of resistance, can be indicative of a potential for equipment failure or it could indicate a possible fire hazard.

When arcing occurs, it is often accompanied by heat. However, it is not always possible to detect a hot spot if the equipment is covered.   Ultrasound will hear arching in circuit breakers, switches, contacts and relays. In most instances, a quick scan of a door seal or vent will detect the ultrasound emission. Listening for internal arcing in circuit breakers and switches can be accomplished with the contact probe. For example, touch a circuit breaker switch with the contact probe to listen for internally generated arcing. The most effective method of low-voltage inspection will be to combine infrared imaging with an ultrasonic probe. Please keep in mind that since air cannot be a conductor of electricity below 1,000 volts, corona cannot exist. Any buzzing sounds are either loose components vibrating or tracking.