Multimeter

Tutorial

Skyline U Training

Overview

The digital multimeter or voltmeter is one of the most common and useful tools for taking electrical measurements. The multimeter is most commonly used for measuring Voltage (AC and DC), Resistance (Ohms), Amperes (Current), and Continuity.

It is extremely important to understand the basic functionality of a multimeter to avoid damaging it.

Setup

Most multimeters have either an On and Off switch or an option on the dial to turn off the meter. Be sure to do so to preserve battery life.

There is a red and black probe that comes with the meter. The Black probe is the "Ground" or "Common", the Red is the "Positive"

For Home security work the Black probe will ALWAYS be plugged into the COM terminal. The Red probe will ALWAYS be plugged into the terminal for the tests we need to conduct with the multimeter.

Testing

AC Voltage:

AC stands for alternating current. It is the type of current used in wall outlets, hardwired systems, Honeywell panels, and doorbells

Turn the dial to ACV, VAC, or V~ and the 200 setting.

Touch the end of each probe to the terminals, wires, or outlet that you are testing.

DC Voltage:

DC stands for Direct Current, meaning Polarity (+/-) matter. Commonly used for 2Gig and Qolsys panels, thermostats, and some cameras.

Turn the dial to DCV, VDC, or V-- and the 200 setting ( you can drop it to the 20 setting if needed)

Touch the end of each probe to the terminals or wires you are testing. Don't worry about the polarity; if you get it backwards it will just read back as a negative number.

Continuity:

Continuity tests are used to determine if the wire you are using is still good, or if it has a short in it. It is very helpful when testing hardwired zones to determine if there is an issue with the switch and magnet, or with the wire.

Turn the dial to the setting that looks like a WiFi symbol. Touch the probes to the end of each wire. The meter will read either 1 (usually beeps too) if the wire is good, or 0 or close to 0 if there is a short in the line if it is bad.

Note: The opposite end of the zone must be "closed" for an accurate test. It must be a complete loop to work properly.