Guide: How To Test For Continuity With A Multimeter
Have you ever wondered why after buying new batteries your flashlight still won’t turn on? Or when you changed the fuse in your car for the dome light, they still don’t work? Or anytime a device that’s plugged in doesn’t seem to be receiving power? This may not happen very often, but the great thing is that you can find out if it’s a power supply issue or not by using a simple to use multimeter at home – and don’t get scared away by terminology, I’m not an electrician and even I figured out how to use one of these little guys.
What is a multimeter?
First off, lets discuss what a multimeter is. A multimeter is a device that checks the current running through a fuse, device, wire, or soldering. In the examples I will give today, we are checking for continuity so that means we are trying to determine if an electric flow entering one part of a device/wire will end up flowing to the other end of the device/wire. This will tell you right away if either there is a blockage or a break in the connection. Now there are many other uses for a multimeter but we will focus on continuity for today and get to the harder stuff in another segment.
Below is an example of a multimeter. These can typically run from $20-30 dollars depending on the brand and store. You can usually find these online quite cheap.
Explaining the settings of a multimeter
The multimeter has many settings, but the one that you will want to focus on is the one that looks like a wifi symbol. In the image above, we have circled the continuity function for you in yellow. This may change in location on different devices and we have also noticed some international brands may have a circular type function. You can always check the manufacturer’s guide for clear direction on which setting is the continuity function.
How does continuity work?
Essentially the way the device works for a continuity check is you have two “terminals” which are the black/red plastic handles with a long pointed metal piece on the end. When you set the device to continuity setting it will send a small trickle of energy out to one terminal and the other end looks to receive that energy source. When the device starts in continuity mode the screen typically will not show numbers in a decimal format. It will typically have a zero on the left-hand side which means “infinity” because the device is sending out an energy source and it’s going nowhere.
What can you check with a multimeter?
Now to check continuity, the object must have no current electricity flow so make 100% sure that it is not plugged in and the batteries are removed. I don’t want you getting zapped like you touched an electric fence or anything! Typical items that you would be checking for continuity could be fuses and wires. Each of these will have an entry and an exit point. Checking fuses becomes really important so that you don’t waste money buying new fuses when it wasn’t even the issue to begin with.
Using a multimeter to check a fuse first will ensure you know that the fuse is truly blown out already and needs to be replaced. If after a continuity check it’s still functional then you know that it’s not a fuse issue and can quickly move on to the next step. In the case of wires, you can sometimes have 5 different wires and not sure which beginning wire goes with the end wire.
If you are not able to physically trace the wire to the end point due to a blockage (often this happens in cars, furniture, or walls can get in the way even), you can use a multimeter to locate the other end of the wire through a continuity check.
By the way, you can check this video to make sure you know how to use a multimeter:
Check your multimeter device first
To test the multimeter device to ensure that it has a strong enough battery and is functioning correctly, start by turning on the continuity mode and then touch both the red and black terminals together. If your device shows 0.00 then your battery on the multimeter is in good condition. If it is far from 0 then you will need to change the batteries before continuing. Some models may not have a 0.00 mode and instead they will just beep when they have acknowledged continuity is present.
How to use the device for checking continuity
Now that you know the device is functioning properly you can then test an object. To do this you will take one terminal end and, in the case of a fuse, place the one terminal on the metallic receiver (The entrance/exit points of every fuse can be different but check for two metal pieces sticking out). Then place the second terminal on the other metallic receiver. Just to note; you need to ensure the terminal is placed on the metallic part since metal is the only good form of material that transfers electricity. If you place it on the plastic parts, it will likely still say “infinity” because electricity can’t flow through plastic.
If the current goes through the fuse, then the multimeter will show close to 0.00 on the screen and you will know that you have continuity. Just to note, often you will never achieve a perfect 0.00 and there is no reason to get it exact. If you are within a small decimal point away then you have nothing to worry about. When you start getting into the whole-digit and double-digit numbers then will know that there is some type of blockage and that the electricity flow is not able to go through the fuse/wire successfully and it’s time to go buy a new one.
You can complete this on many other devices, fuses, wires, and metal objects. Feel free to walk around your home and try this on door knobs and other fun metallic objects to play around with it. While a multimeter has a broad range of functions that we didn’t discuss today, I hope this overview has helped you to feel more comfortable with understanding what it is and how you can use it to help solve simple at home problems with ease.