Twenty-four-volt electrical systems are powered by a transformer or battery. If the electrical equipment linked to your 24-volt electrical system isn’t working, then you need to find the problem. The best way is to undertake a systematic test of the wring starting at the power source and ending at the electrical device. Using a multimeter to test the flow of electricity throughout the electrical system is the simplest way to find any problems.
Turn on your multimeter and set it to read volts. Set the range on the meter to between 20 and 30 volts so you can find the problem in your 24-volt electrical system.
Check the connections at the power source. Ensure the wires are connected correctly and securely. If any are loose, tighten them.
Turn on the power source. Place the multimeter’s metal sensors on the end of the black and red wires onto the two power source terminals. Put the red wire onto the terminal labeled “+” and the black wire onto the terminal labeled “-.” Read the voltage on the multimeter. If it reads approximately 24 volts, you know the power source isn’t the problem. If there’s no reading or the voltage is less than 15 volts, either the multimeter's battery needs charging or the transformer isn’t working correctly.
Follow the two wires from the power source (once you’ve eliminated it as the problem) until you reach the next wired connection. This is likely to be a switch of some type. Remove the screws from the switch cover using a screwdriver, then remove the cover. Place the multimeter wires on the first two terminals in the switch unit: red to “+” and black to “-,“ as before. These are the terminals the wires from the power source connect to. Read the display. If the reading is approximately 24 volts, power is getting to the switch. If there’s no reading, then the problem is the wire from the power source to the switch.
Place the metal sensors on the next set of terminals in the switch. The wires connected to these terminals go to the electrical device. Ensure the switch is in the “on” position. If power is leaving the switch, the meter will read 24 volts. If there’s no reading, the switch is the problem and needs replacing.
Follow the wires from the switch to your electrical device. Place the two sensors onto the terminals of your electrical device as before. Read the meter display. If it says 24 volts, power is getting to your device; in this case it is your device that’s the problem. If there’s no reading, the problem is the wire between the switch and the electrical device, so replace the wire.