What is Non Contact

A non-contact voltage detector is an instrument that detects electric and electromagnetic fields, which are emitted from all electric conductors. There are two types of testers, the most common is the capacitive tester which is used in both electric and electromagnetic fields. The second type is the inductive tester or current tester which detects mainly current or electromagnetic fields. The differences between the two fields are:-

• The electric field strength is proportional to the voltage, which is the pressure at which electricity is pushed through the wires.
• The magnetic field strength is very much proportional to the current, which is the amount of electricity flowing in the conductor.

In both of these two systems the direction of the currents magnetic field changes direction at the rate of the frequency of the transmission line.

Diagram magnetic field around power poles and magnets

The GL McGavin range of testers detect both electric and magnetic field. These fields are detected by the testers and converted into an audible and visual indication.