Circuit tracers or signal tracers are used to troubleshoot circuits. They are relatively simple electrical testing instruments that enable electricians and other users to locate, trace and identify common electrical problems such as breakers, shorts, and open circuits. Some circuit tracers can locate wires behind walls, underground, and inside junction boxes. Others are designed to find blown fuses or test light fixtures. Circuit tracers and signal tracers that can locate neutrals, ground faults, and high voltage lines without power interruption area also available. Most products are capable of continuity checks and audible continuity measurements. Continuity checks test a circuit for completeness. Audible continuity measurements beep when probes touch each other. 

There are several different form factors for circuit tracers or signal tracers. Benchtop instruments are designed to sit atop a bench, typically in a laboratory setting. Free-standing standing units have a full case, cabinet, or integral interface. Clamp meters are circuit tracers that measure current through wires which are still connected to the circuit. Rack-mounted circuit tracers include hardware such as rail guides, flanges and tabs for mounting in telecommunications racks. Handheld signal tracers are designed to be operated while held in one hand. Circuit tracers with a computer-board form factor are printed circuit boards (PCBs) that plug into computer motherboards or backplanes. Electrical test equipment with other form factors is also available. 

Output interface is an important specification to consider when selecting circuit tracers and signal tracers. Choices include universal serial bus (USB), general-purpose interface bus (GPIB), RS-232, binary coded decimal (BCD), and digital-to-analog (D/A). Selecting circuit tracers also requires an analysis of features such as overload protection, battery power, and visible alarms. Circuit tracers with overload protection have fuses or other components to protect internal circuitry from voltage spikes. Battery-powered devices are lightweight, portable, and suitable for in-field use. Circuit tracers with visible alarms contain light emitting diodes (LEDs) that light when the root mean square (RMS) value or peak value is greater than a given range. 

Many circuit tracers and signal tracers bear quality marks and/or comply with recognized standards for safety and performance. CE Marking indicates that a circuit tracer complies with the essential requirements of relevant European Union (EU) directives that uphold national standards for health, safety, and environmental protection. Circuit tracers that bear a CSA Mark have been tested by the Canadian Standards Association (CSA) and meet applicable standards from organizations such as Underwriters Laboratories (UL). Recognized standards for safety and performance include the EU’s Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronics Equipment (WEEE) directives. IEC 61010 from the International Electrotechnical Commission (IEC) is another important standard.