Using a Multimeter to Check Voltage, Continuity, and Resistance   

Multimeter - electronic device

As a lighting professional, you’re likely aware that multimeters are vital tools for assessing an exhaustive range of electrical elements. They’re wildly versatile, a breeze to operate, and their ability to streamline operations makes it a no-brainer when considering adding them to your toolbox. We’ll briefly explore the advantages behind these trusty instruments and how they, when used properly, can return multiple times their cost with just a couple of uses.  

Multimeter vs. Voltmeter  

If you’re in the lighting business and have yet to reap the benefits of a multimeter, it’s time to get on board with this tool that’s been around since the 1920s—plain and simple. Perhaps you’re a voltmeter purist and don’t see an immediate need to upgrade. While a voltmeter is perfect for scoping out voltage drops, a multimeter is the Renaissance Man of electrical system measuring, capable of troubleshooting almost every electrical fault. No matter how often you use multimeters, there is always more you can coax out of them with the knowledge of how they work. Let’s examine how you can use multimeters to upgrade your proficiency and simplify your professional routine.   

How to Use a Multimeter to Check Voltage  

  1. Plug the multimeter leads into the terminals. For those who are unfamiliar, the terminals are usually color coded, with red for positive and black for neutral or common. Some multimeters have two positive terminals: one for Voltage and Resistance and the other for Amperage. 
  1. Set the multimeter to volts AC (V + ~) 
  1. Set the multimeter to 120 V. 
  1. To test the outlet, first unplug the transformer from the outlet. 
  1. Holding the probes by their insulated handles, insert the black neutral wire into the outlet’s larger neutral slot before inserting the red hot wire into the smaller hot slot. ALWAYS insert the neutral probe in the neutral slot first. If you start with the hot slot, the other multimeter probe becomes energized, increasing the risk for shock.  
  1. The multimeter should display 110 to 120 V. If not, it might require replacement.  
  1. Insert the neutral probe into the ground slot then the hot probe in the hot slot to verify if the ground wire has a complete path back to the breaker panel. 
  1. To test the transformer, plug the transformer into the outlet, leaving adequate space to access the outlet inside the transformer.  
  1. Place the black and red probes into the neutral and hot slots respectively. As with the outlet, if the reading is significantly estranged from 120 V, there might be an issue with the transformer. Sometimes transformers can get overloaded or burned out. If the transformer is an older model, it’s likely to have visible evidence of wear and tear, meaning it needs immediate replacement.  
  1. To test the wires, head to the end of the wire run.  
  1. Touch the probes to the exposed copper ends to obtain a reading of 12 V. The closer to 12 V the lamp can get, the longer it’s expected to last. If it’s falling below 10 V, it might not be receiving enough power. To rule out this possibility, check connections between the lights with low power. If you have a hub, make sure the connections are secure and corrosion-free. 

How to Use a Multimeter to Check Continuity and Resistance 

A common use of continuity testing is checking the functionality of a power cord. 

  1. Set the multimeter to Ω (ohms). 
  1. Disconnect the power from the circuit breaker.  
  1. Touch one of the multimeter probes to one of the prongs on the male side of the power cord. 
  1. Insert the other probe into the corresponding slot on the female end of the cord. If there is continuity, the multimeter will release an audible beep. 
  1. Repeat this process on the remaining male prong and female slot. If there’s no beep on either side, the power cord needs replacement. 
  1. Touch one of the probes to one of the prongs on the male end of the cord and the other probe to the other male prong on the same end. If the meter beeps, there might be a short and the cord needs replacement. 

If your multimeter isn’t equipped with a continuity setting, no problem—you can still test the Resistance. Simply turn the selection knob to Ω (ohms) and follow the same steps as the Continuity testing procedure. However, instead of listening for a beep, you’re looking for a 0 and 1 on the display. If the display reads 1 or OL (Open Loop), the cord should be replaced as it lacks continuity. 

If you require further information regarding multimeter testing, our expert Customer Service representatives are ready to help.  

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