A multimeter, commonly referred to a voltmeter, is a very handy tool to have around your house. It can be used to diagnose a huge array of problems you may encounter. Multimeters can be incredibly expensive and also incredibly cheap depending on what kind you get. While there are some really nice digital multimeters out there today I’m going to talk about using a cheap analog multimeter. I paid about $10 for the one shown in this article and video but I’ve seen basic multimeters sold for about $3 in dollar stores.
The wires that come with a multimeter are called leads and the connections for these wires are labeled + and -. The red wire is connected to the + terminal and the black wire is connected to the – terminal. These are normally color coded but if they aren’t just think of an automotive battery. The red is always positive on a car battery.
A multimeter will do a lot more that what I will cover in this article. Here I’ll show you an example of using the DC voltage, ohms or resistance, and AC voltage settings. Before using the ohms settings you need to calibrate the meter. With the multimeter set to the highest ohms setting and both of the leads touching the meter should read 0. There is always an adjustment somewhere on the meter to move the ohms reading if needed. Adjust the scale so that it reads 0 with both leads touching.
The ohms setting is used to determine if what you are testing is forming a closed path or if it has a break in it. In the following example the meter is reading 0 when I connect the leads to each end of the white wire. This tells me that there is a continuous path through the wire for electricity to flow through. If there were a break in the wire somewhere the meter would not read anything. You can use this concept to test a variety of items in your home such as a regular light bulb, an electric stove eye, or a water heater element.
In both the DC voltage and AC voltage modes there are multiple max voltage numbers for you to select from. You never want to test something with a known voltage higher than the max voltage you selected. In this example I am testing an 18 volt battery. The two settings closest to 18 volts on the DC side of this multimeter are 10 volts and 50 volts. If I use the 10 volt setting the battery would be higher than the maximum reading for that setting and could cause damage to the meter. For that reason the 50 volt setting was used. On a DC battery it is important to connect the leads to the correct sides of the battery. The red wire is connected to the + side of the battery and the black wire is connected to the – side of the battery. This multimeter is reading 18 volts DC which is correct for this battery.
The same maximum voltage setting rule is true for AV voltage but this time you can use either color lead on both sides of the wires. A common household circuit in the United States is 120 volts (commonly called 110). The next highest setting above 120 volts is 250 volts on this particular multimeter. With it set to 250 volts and both leads inserted into the receptacle slots the meter is reading 120 volts. This tells me that there is power to this receptacle and I need to turn the power off before servicing it.
Any time you have exposed wires that you are about to work on it is important to test the wires for voltage before you work on them. If the multimeter does not detect any voltage when testing the exposed wires than this means there is no electricity supplied to this wire and it is safe to work with.
This is just a brief overview on what a multimeter can be used for around the house. If you have any tips tricks or suggestions on how you use a multimeter please leave them in the comments below. Your input can really help the next person who may be in a similar situation.