Troubleshooting a Low Voltage Lighting Transformer

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Low voltage lighting transformers have become commonplace in many of today’s homes with the increase awareness in energy efficient lighting systems and decorative accent lighting. A low voltage lighting transformer is a device that converts the standa

Low voltage lighting transformers have become commonplace in many of today’s homes with the increase awareness in energy efficient lighting systems and decorative accent lighting. A low voltage lighting transformer is a device that converts the standard 110V or 120V household voltage to a lower voltage such as 24V or 12V. Low voltage transformers can be installed outside in a weatherproof enclosure, or in a basement or garage to power low voltage landscape or deck around the home. The transformer can be hard-wired to the home’s electrical system or plugged in to a receptacle to power the transformer and then a smaller gauge cable distributes 12V to various lighting devices.

The purpose of a low voltage lighting system is to reduce the size of the wiring, increase the number of lights on a circuit, and make installing light fixtures quick and easy for the do it yourselfer and professional alike. Lowering the voltage supplied to the fixtures reduces the chance of injury in the event a wire is damaged, but other problems can occur that can reduce the effectiveness of the light system.

 

Typical Low Voltage Lighting Circuit

Troubleshooting

The Lighting System is Completely Off

If the whole lighting system is off the first item to check is that there is power to the transformer. If the transformer is plugged in, make sure that the circuit is not tripped to the receptacle. Transformers installed outside are typically plugged into a GFCI receptacle, so make sure that the receptacle has not tripped. After several years the GFCI receptacle may need to be replaced. Check the electrical panel and verify that the breakers are not tripped or turned off. Use a volt meter to check if there is power to the receptacle or transformer. In some cases the timer has not been set properly, or if there has been a power outage, the time may be off by several hours. Reset the timer inside the transformer and verify that the lights are on.

Fuses, Breakers, and Overloading

Another common problem that may cause an issue is a blown fuse or tripped internal breaker that may be installed in some units. Transformers have a power rating in Watts, such as 600W, 900W, and 1200W. The system may be overloaded with too many lights, or lights that exceed the recommended wattage. Reduce the number of lights and replace the fuse or reset the breaker to restore power to the lighting system. A damaged wire may also cause the breaker to trip. If you have too many lights installed on your system you can installed a new transformer with a higher capacity as long as you do not exceed the amperage of the circuit in your main electrical panel.

Fuse in the bottom of a Lighting Transformer

Individual Lights

If there is only one light out, the issue may not be the transformer but a loose bulb or connection. To troubleshoot this problem, verify that the bulb is connected properly in the socket and that the filament is intact. If the light is still out, inspect the wire connecting the light bulb to the main cable and verify that it is not broken. In order to check if the wire is not broken, you may need to use of an ohmmeter. Shut off the power and check if the reading is high or low. The wire is broken if the reading is very high and will require a change in wiring. A string of lights may also be out if there is a break similar to Christmas lights.

Dimmed and Flickering Lights

Dim lights are the result of an overloaded transformer, but not overloaded to the point of tripping the breaker or fuse. To solve this problem a new transformer with a higher capacity needs to be installed since all transformers have a power capacity. Other problems that can lead to dimmed lights are undersized wiring between the transformer and the lighting devices and poorly spliced and terminated wires. The length of the wire is also a factor as very long runs will reduce the voltage to the light and cause it to be dimmer. Review the installation manual for your transformer to determine the proper wire sizes and quantity of lighting devices.

You may be able to install an additional transformer and separate a few of the lighting runs. The problem with this is that the timers will need to be synchronized so that the lights go on at the same time.

2 comments

Evan Levine
10
Posted on Sep 23, 2018
Shams Premji
10
Posted on Jun 25, 2018