Minimum load: Requirements for electronic transformer are as follows:

There is no minimum load requirement for magnetic transformers.

Maximum load: Recommend use up to 85%. While all Prima magnetic transformers can be loaded 100%, when dealing with halogen bulbs, we often see an actual load of up to 5% more than the calculated load. In addition, the wire, connectors, ambient temperature, etc. are all variables that may affect the total load on the secondary circuit.

• Check transformer “installation instruction” to make sure the transformer is wired and positioned correctly in an area where ventilation is good and temperature is not to exceed 104 degrees.
• If a dimmer is used, be sure it is compatible with the transformer. Bypass the dimmer to see if it will eliminate the problem.
• Be sure not to overload the system. Maximum wattage of the fixtures should not exceed the transformer capacity. Please refer to “maximum load requirements”.
• Make sure proper secondary wire is used. For a 300 watt circuit, use THHN stranded 10 gauge wire. 12 gauge wire is only rated for 20 amps or 240 watts at 12 volt. If the run is long, it might be wise to use 8 gauge wire to insure proper voltage at the fixture. Please refer to “Voltage Drop Chart” for the secondary wire length.
• Turn off power to system and check all connection points including wires inside the transformer, power feed, connector, fixture adapter and lamp. Make sure all connections are secure and there is no short.
• If the breaker is still tripping, remove all lighting elements and reset the breaker. Re-install one element at a time and check if the system works to find the defective elements.

• It is normal to hear a slight humming or buzzing from magnetic transformers.
• If the humming or buzzing is loud and a dimmer is used, check if the dimmer is compatible with the transformer. Bypass dimmer to see if it will eliminate the problem.
• Make sure proper secondary wire is used. For a 300 watt circuit, use THHN stranded 10 gauge wire. 12 gauge wire is only rated for 20 amps or 240 watts at 12 volt. Please refer to “Voltage Drop Chart” for the secondary wire length.
• If it is a remote magnetic transformer, be sure it is placed with breakers facing down.
• If a surface mounted transformer is used, check if the plastic insulator is in position and the metal plate is secured tightly to avoid buzzing.

• To test electronic transformers, a “Fluke 87 III True RMS Multimeter” tester must be used due to high frequency. Other testers may give an inaccurate reading because they might not be able to detect the high frequency. Recommend use a lamp and test directly to transformer blue leads to confirm if transformer is still operational.
• If a surface mounted transformer is used, it has internal reset-able protection. Auto heat regulation automatically acts as overload protection. Auto-reset thermal cut-off when temperature is too high.
• If a remote magnetic transformer is used, check the connections inside the transformer and see if a proper wire nut has been used. Breaker maybe damaged due to non-compatible dimmer, improper secondary wire, reset too quickly, or excessive heat from arching.

• A multi-tap transformer is one that has several voltages on the secondary side, usually at 12, 13 and 14 volts.
• For a 12 volt system, always wire with 12 volt tap first. If the transformer is placed far away from the lighting system and the correct wire (10 gauge minimum) has been used, use the 13 volt tap when the voltage at the lighting system is 10.5 volts or below.