Exposing a device to a high voltage test won't damage the equipment as long as the test is performed properly. Careful attention to the steps below ensures the safety of both the technician and the circuitry.

Why Do a High Voltage Test?

The main reason that technicians perform this is to ensure each part of a circuit is isolated from the rest. Small defects in a circuit might not short under normal testing but would eventually cause catastrophic failure in the equipment. A small nick in the insulation, corrosion around the conductors, improper terminal spacing or many other problems could be sources of short circuits.

This test is also called a hipot (high potential) test, is different from the continuity test most technicians are familiar with. A continuity test ensures current flows easily where we went it to. A high voltage test checks that current doesn't flow where we don't want it to. The high voltage pushes the system beyond normal operating limits so electrical "leaks" can be found easily.

How to Do the Test Safely

The equipment tested does not have to be rated to handle the voltages used in a high voltage test. The reason is the circuit will be tested carefully so that no voltage drop occurs across delicate components. Remember the problem is current not voltage, and current can't flow if there is no voltage drop.

The circuit should be studied carefully and broken out mentally into networks. Any two or more points connected by wires could be considered a network. If a network to be tested has only wires, the voltage can be applied safely. If a network contains components such as resistors or capacitors, voltage must be applied to all points in the network in such a way that the voltage on either side of any component is the same. As long as both sides are at the high voltage, no current will flow and the component will not be harmed.

Use High Quality Testing Equipment

Since high voltage testing carries the potential for damage to the equipment or harm to the technician, only top quality brands should be used. Imprecise voltages could cause current to flow at the wrong time, destroying components.

Technicians should be well acquainted with the functions of the testing equipment. Not all models work the same so don't assume one model operates as another one does, even if they are made by the same company. Technicians should practice on junk equipment until they have the technique down. In this way, if they make mistakes no expensive equipment will be damaged.

Once a technician has performed high voltage testing a few times, it becomes routine. Circuits can be tested quickly and safely, ensuring the integrity of the connections and the safety of the equipment.