How to Use a Multimeter for Stage Lighting + Buyers Guide – Learn Stage Lighting .com

How to Use a Multimeter for Stage Lighting + Buyers Guide

One of the top 5 tools that I recommend to anyone getting into stage lighting is an electrical multimeter.

Old Multimeter

An old voltmeter. Photo Credit: russell_w_b via Compfight cc

An electrical multimeter allows you to test, check, and diagnose a variety of electrical circumstances and problems.

And, if you’re diving into stage lighting seriously, a good meter is a tool you must own before your first show!

If you already have a meter – stay tuned, because I will probably teach you a new use for your meter below that you weren’t aware of- these things are just so darn useful!  Then, at the bottom of this post I’ll show you what meter I own, as well as what meters I suggest for users of all types.

Disclaimer: This post is here to inform and entertain, with the understanding that electricity is very dangerous and kills many people every week.  

Don’t ever work with electricity if you don’t 100% know what you are doing and don’t ever work on hot electrical power.  Thank you!

Multimeters 101

When I first started in this business, I mentor of mine suggested that one of the first tools I needed was a decent multimeter.

Not fully understanding what “decent” meant, I went out and bought a meter for $10, and it lasted a little while until I watched it shoot sparks while in my hands testing a 3-phase power disconnect!  Thankfully, I was fine, but a little bit spooked by the experience!

At that point in my career, I didn’t know a thing about my meter, and all I knew how to test was AC voltage – and boy was I missing out!

Though I owned a multimeter, I clearly didn’t see the “multi” in it!  It was like when I first got my Leatherman and only used the knife and pliers!  All of the other symbols and letters on the dials was just greek to me, but boy would I learn!

Fast forward a few months, and I was taught the concepts of ohms, DC voltagecontinuity and amperage and exactly how to test and/or troubleshoot all of these in various scenarios and situations.

I had a patient and servant-hearted mentor, and today I want to pass this information on to you so that you can learn more about stage lighting and grow in your knowledge.

So let’s jump right into it with voltage!

Voltage

Voltage is one of the aspects of power that we can measure and use in a couple of different ways with out multimeter.

The first important distinction to know is that there is AC voltage and DC voltage.  And that they’re different.

Though I’m not going to go super in depth here on how electricity works, AC voltage is what we in America use for “wall power” and DC voltage is what most electronics convert power to to use, and all car/boat/rv/truck power runs on DC current.

We can measure voltage using out multimeter very easily.  First, setup your probes where indicated on the meter for the type of current you are measuring.  Some meters will be “auto-ranging” and will move the “scale” of voltage that you’re measuring automatically.  Others will display “overload” or a very small number when you get out of range in either direction, and you can adjust your range on the dial.

Multimeter for stage lighting

Photo Credit: reidbrothersuk1868 via Compfight cc

Some meters don’t require you to move your probes for AC and DC voltage, whereas others do.  If your meter has (2) “hot” probe connections, one is for your DC and one is for AC.  The neutral/negative which is usually black will stay in the same plug for AC and DC.

Next, turn your meter on and onto the voltage selection. From here, you may now check AC power by either sticking the probes in a outlet or test points on a cam-lok panel.

With a commercial power system, you should see around 120v between any hot leg and ground OR neutral.

Ground to neutral should be no greater than a few volts without equipment running, and 2 hots together will measure around 208v.

In a residential/home power system, the hot legs are 115v and sum together to make 230v, or right around there.

DC voltage, on the other hand, really depends on what you’re measuring, but is around 12.8v for a car battery, and less for small motors in moving lights and other devices like that.

Amperage

Clamp Multimeter

Photo Credit: tronixstuff via Compfight cc

Amperage is the measurement of how much power is being drawn from an electrical service.

To measure amperage, you need to have a cable that separates the hot conductors from each other and neutral and ground, or cam-lock feeder cable.

So, it’s easiest to meter inside an appliance, or on your feeder cable.

You’ll also need a clamp multimeter, as the amperage is measured using this specialized device. You can measure amperage to check the loads of different legs of your power or to hunt down an electrical problem without having to expose bare wire. You simply clamp the meter around the hot wire, set your meter to test for amps, and you’re good to go!

You’ll see your amperage, and be able to watch it fluctuate as you bring lights up or down! Remember, you have to have a separate hot wire for this to work.

Ohms/Continuity

Our next step on this super fun roller coaster is ohms and continuity.

What are ohms you ask?

A measure of impedance.

What is impedance you ask?

Impedance is a how electrically resistant a given object is.  We as humans have impedance, as do electrical cables, speaker drivers, lighting lamps, etc. Everything has electrical impedance.

With lighting, we don’t actually measure impedance very much, but we do use the continuity beeper on our meter when things break! The continuity beeper on our meter sends a little bit of voltage through one probe and when it hits the other probe, you hear a beep from your meter.

This is perfect for testing bad cables, as you can quickly place your probe into each of the connector on each pin, and find out a) are you getting continuity across the cable and/or b) are other pins getting continuity from the wrong pin!

It sure beats guessing, and you can quickly use it to diagnose bad cables or possible issues with data/power transmission.

Just like testing a bad cable, you can also test incandescent lamps with the same function on your meter.  Simply meter between the 2 pins that lead to the filament on your lamp, and if you don’t hear that beep, the lamp isn’t going to work!

Wrap Up

These are the basic functions that I use on my meter on a weekly basis in stage lighting, and hopefully this guide has taught you something new that you didn’t know about your meter, or perhaps has influenced you to buy a meter yourself.

Either way, let’s jump into the features you need to look at when buying!

What Meter Should I Buy – The Multimeter Guide

First – The Big Features

When you’re looking to buy a multimeter, there’s a few big features that you really can’t miss.  Or maybe you can.

Either way, here are the big features that you’ll see and a quick explanation of whether you need them or not:

Auto-Ranging

You need this one!  Only the cheapest of the cheap, $5 meters and old meters don’t auto range.

I touched on this above in the section on voltage, but the auto-ranging capability is useful in all of the different zones of your meter.  Basically, it searches, measures the current(or ohms, amps, etc), and then moves the decimal point around for the optimal reading to you.

If you don’t buy an auto-ranging meter, you’ll have to move your dial around and watch the meter re-read the signal every time you go and meter something.

This used to not be such a common feature, but now pretty much all meters have it, and so don’t buy a meter without it!

True RMS Measurement

When you’re measuring AC voltage in particular, mechanical equipment such as motors and large power supplies can really mess up the sine wave of power.

Why do we care?

The distorted wave can throw off your measurement by as much as 40% according to lab tests.

So, if it is essential that your meter is more accurate than simply telling you whether you’ve got 120v or not, you should probably invest in a true RMS multimeter.

Beginners need not invest, as these meters start around $70 and go up from there, but if you’re serious about lighting, it’s a good idea so you can be sure your meter is accurate!

Backlight and Screen

A backlit screen helps you see your meter in the dark.  (No way!)

It’s a good idea, but I’m not gonna go out and say it’s essential.

But, it is nice when you’re metering power in a dark corner or closet and you can just click the button and have a great view of the screen.

Thinking of screen – most meters these days have a digital readout – just get one!  It’s so much easier than following the old needle!

Stand and Case

If you’re going to carry your meter around with you, you want to be sure it comes with a decent case.

Some meters come with a soft, zippered case, and others are built into the meter and flip down to cover the screen.  Both are great, it’s just important to protect your investment!

And if you’re doing a lot of “bench work”, then a meter with a built-in stand it helpful so you don’t have to stretch your neck to read the display. Not essential, but nice to have if you’re going to be sitting down and metering a bunch of bad cables or something!

Buying a Meter

Whether you’re new to lighting, or have been around for awhile, it’s really important to have a meter that meets your needs.  Here are 4 great meters that I’d recommend, to whom and why:

Cheap meter

This inexpensive meter by INNOVA retails for around $25 and is perfect for occasional usage.  

It’s benefits include auto-ranging, protective rubber corners, a nice big digital display and a great price! Naturally, this meter feels cheap to the touch, and you should take care of it.

But, for the price it’s a great value and perfect for someone who’s just starting out.

Medium Level Meter

This meter by Klein is a step up from our “cheap meter” in that it is built tougher, has a backlight, 3/4 protective case and a stand.  The case doesn’t cover the front, but you can buy one for the meter if you want.

It’s got pretty much everything you’d want except true RMS metering and a amp metering clamp.  It’s affordable, and one user reported dropping it off of a 2-story roof – and it still works!

The Meter I Own

The Tenma 7226 is a great meter.

It is the meter I own, and it comes with a case(no stand) , has that clamp for ampacity metering, and is tough!  It’s got true RMS metering, and does everything I need it to do.

It’s a little pricier, but if you make your living taking care of expensive electrical equipment, it’s totally worth every penny! The only thing that really bugs me occasionally is the lack of the backlight.

But I always am carrying my maglite anyways, and what exclaims safety like holding a maglite in your mouth and metering high voltage power in a dark corner?

The High End

Fluke is the undisputed leader in multimeter production.  These are the showcase meters that HVAC tech’s and other technicians who rely on meters constantly use.  

Honestly, these are a little too pricey for me, but they are darn tough and accurate.

The company I work for owns a few of these, and it’s a nice meter.  

Would I buy it with my own funds?

Nope.  Way too pricey!!!


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