How to Test a Metal Halide Ballast with a Multimeter

How to Test a Metal Halide Ballast with a Multimeter. Is your metal halide bulb unable to work effectively and fluctuate? If yes! In this case, you might need to test the ballast before the lamp explodes. The explosion is because of the tube inside that ballast that eventually fails and causes it to explode.

How would you find if the ballast is prone to damage?

How to Test a Metal Halide Ballast with a Multimeter

It’s simple! Check out these signs.

If any of them exists, you need to test the ballast to find the cause.

  • Flickering
  • fluctuations
  • Buzzing
  • Delayed starting of bulb
  • Low output
  • Inconsistent lighting levels

Safety Equipments and Tools 

Whenever you are working with an electrical device, safety comes first. Maintain proper safety measures before conducting a test.

To avoid any mishaps, try using these:

  • Electrical personal protective equipment before testing the Ground fault circuit interrupter.
  • electrical insulated rubber Gloves 

A multimeter helps you troubleshoot the ballast. You can find the resistance and voltage of electricity. Analog Multimeter is cheaper than a digital one because the digital multimeter is advanced in its results-giving capabilities.

So if you want to test the ballast, try the advanced version by using a digital multimeter. Remember not to get confused by the name. MM is also known as the volt-ohm meter.


  • Multimeter 
  • Specifications manual 
  • Screwdriver
  • Ballast 


Locate loose sockets 

Before testing the ballast, check the lamp. There might be a loosened socket preventing the bulb from working efficiently. Tighten it and check the efficiency.

Look for color change or bulging 

Before testing, observe the ballast physically for any color change or bulging.

Look for leaky sites

Before testing, expose the ballast. Remove the protective covering using a screwdriver. Identify any leaky areas. In case of any leak, replace the ballast.

Look for the blown-up fuse

Also, check any blown fuse that needs a repellent. If the bulb is damaged, replace it with new.


Testing Resistance Using Digital Multimeter

  1. Take your multimeter and set it to ohms.
  2. The range must be 1000 -2000.
  3. Set the multimeter to 2000 ohms.
  4. Take the black lead of the multimeter and attach it to the white wire of the ballast.
  5. White wire represents the ground wire.
  6. Take the red lead of the multimeter and start checking for resistance in other wires.
  7. Other wires include black, blue, red, and yellow.
  8. Black wires are considered power wires.
  9. After testing all wires, note down the values for each wire.
  10. In case of maximum resistance, there is an open line.
  11.  It indicates the ballast is working well.
  12. In case of no resistance, the ballast is defective or short-circuited. 

Testing Ballast Output Voltage Using Digital Multimeter

  1. Maintain safety measures.
  2. Carefully read the ballast manual for specifications for voltage, wattage, and type of lamp employed.
  3. Make sure that the specifications are in consideration of the bulb.
  4. Switch off the power supply.
  5. Tighten the loose connections with the help of a screwdriver.
  6. Supply the correct amount of voltage to the ballast.
  7. Standard ballasts require a voltage of 240-volt power.
  8. The voltage is equally distributed, within two hot wires, 120volts each.
  9. These wires are connected separately to each breaker.
  10. Once you have checked all the parameters, take the multimeter and connect it to the lamp.
  11. Turn on the lamp.
  12. Connect the leads of the multimeter to the lamp electrodes.
  13. One time apply the scenario with a bulb while the next time remove the bulb.
  14. The voltage difference will indicate the results.
  15. The voltage readings in both cases must agree with the output voltage mentioned in the specifications.


To check the ballast efficiency, first identify any physical damage of leakage, loose sockets, discoloration, and bulging out of the ballast. Once the ballast is physically fit, go for the resistance and voltage test using a multimeter.

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