Key takeaways
- Add the wattage of every fixture on the system
- Leave about twenty percent headroom
- Long runs lose voltage, so plan the cable
- The Power and Transformer Calculator does the math for you
A transformer that is too small makes lights dim and wears out sooner.
Add the load
List every fixture and its watts, and add them up for each zone.
Add headroom
Plan for the load to be no more than about eighty percent of the transformer rating, which leaves room to grow.
Plan the runs
Voltage drops along long cable runs, so far fixtures can look dim. Heavier cable or extra taps fix that.
Use the calculator
The Power and Transformer Calculator on this site gives you a quick estimate.
Related services
Questions about your own property? Call or text 800-224-9245, or use the estimate form below.