What is a Ground Detector?

Mary McMahon

A ground detector, also known as a ground indicator, is a device that indicates whether a ground is present in an electrical circuit. Such devices are used in a variety of settings, including safety equipment intended to identify problems with a circuit before it malfunctions, endangering people or equipment. They are available from electrical supply stores, and people can also make their own if they have experience with electrical circuits and associated devices.

Working with electrical systems is inherently hazardous.
Working with electrical systems is inherently hazardous.

In a system that is supposed to be ungrounded, the presence of a ground indicates a problem in the system. A ground detector can be used to check for errors and can also monitor a system continuously, triggering an alarm if a ground develops. The devices can also automatically de-energize a system until the problem has been addressed. This is similar to the ground fault interruption devices used for safety in environments like bathrooms and kitchens.

Electricians can perform grounding tests on circuits.
Electricians can perform grounding tests on circuits.

People can also use a ground detector to make sure a circuit is properly grounded. Some surge detectors come with a ground indicator light. If the system is grounded, it illuminates, assuring people that the circuit is grounded and safe to use. If it does not light up, or if a ground fault indicator illuminates, there is a problem with the circuit that needs to be addressed. The warranties on such devices often warn that if the warning lights showing an error with the circuit are illuminated when the device malfunctions, people will not be compensated for damages associated with the malfunction.

Portable ground detector devices are available for electricians and other professionals to use in the field. These devices can be used to test a circuit before use or if the electrician suspects there is an error in the circuit. The ground detector can provide useful diagnostic feedback, especially when combined with an examination of the circuit and checks with other devices. Electricians can also install a ground detector permanently in a circuit if there are special concerns about grounding and safety.

Working with electrical systems can be hazardous, especially if there is a problem. It is important to follow directions with equipment like a ground detector carefully, to make sure it is used appropriately. Special training may be required to work with some kinds of electrical systems and people should call an electrician if a monitoring device is returning an error they do not understand or if they are experiencing severe electrical problems.

Portable ground detectors are available for electricians and other professionals to use in the field.
Portable ground detectors are available for electricians and other professionals to use in the field.

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Discussion Comments


@NathanG - It’s nice that you can get hold of a portable ground fault detector to test circuits around the house, but unless you’re an electrician I wouldn’t chance it. You can electrocute yourself in a hurry and it’s not as simple as a red light, green light on a device. You have to get feedback from the system like the article says.


I’ve never heard of circuits that were not supposed to be ungrounded. I had always thought all circuits needed to be grounded in one way or another. That shows you how much I know about electronics.

Anyway, the ground detector is a very useful device indeed. You should at least understand the concept. It’s amazing the number of people who will buy a surge protector and ignore the grounded warning light which ensures that the protector is properly grounded.

If that light goes bad your protector will fail, and it won’t matter how many “joules” of protection were advertised on the product packaging. It pays to know at least a little about these things if you are going to protect valuable equipment like personal computers.

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