====== Checking Your Ground Connection ======

Throughout this book, we've talked about the importance of grounding for noise control. But how do you know if your ground connection is actually working?

Most wall outlets have a ground connection. Unfortunately, that does not guarantee that the outlet is properly grounded.

In older buildings, factories, or offices, grounding problems are surprisingly common. Sometimes the ground wire was never connected. Sometimes it was disconnected during renovation work. In other cases, the building's grounding system may simply be in poor condition.

Before spending time chasing noise problems, it is worth checking the ground first.

The easiest method is to use an outlet tester. These inexpensive devices plug directly into a wall outlet and indicate whether the wiring and grounding are correct.

{{ :noise_book:tester.png?nolink |}}

A multimeter can also be used, but caution is required since you will be measuring live AC voltage.

Measure the voltage between Line and Neutral first. You should see the normal mains voltage (120V or 230V, depending on your country).

Next, measure between Line and Ground. The reading should be approximately the same as the mains voltage.

Finally, measure between Neutral and Ground. The voltage should be very close to zero.

{{ :noise_book:multimetertester.png?nolink |}}

If these measurements do not look correct, there may be a grounding problem. In that case, the building wiring or electrical panel should be inspected by a qualified electrician.

Many engineers spend hours looking for noise problems inside their equipment, only to discover later that the real problem was a poor ground connection.

[[index|←Noise Is My Friend]]