Relay panels

What to look for

• How many relays, and what each one switches. One relay per zone you actually want to control separately. A single relay for a whole floor is how contacts get overloaded.
• Voltage and load type. Match the panel to the circuit voltage. A rating written for tungsten or resistive loads is not the same as a rating for LED drivers or electronic ballasts.
• Inrush. LED drivers spike well above their running current for a fraction of a millisecond. The relay needs an LED or electronic-ballast rating, and a large group of drivers should be split across relays.
• Zero-cross switching, if the panel offers it. Closing near the voltage zero is easier on LED loads.
• Control inputs. Occupancy sensors, switches, and time schedules have to land on inputs the panel actually has. Low-voltage switches are simpler at the wall. The relay still switches the line voltage.
• Room to add a relay later, a local override, and a clear label for every circuit, including anything on emergency power. Emergency circuits follow their own rules and are not ordinary switched loads.

Common mistakes

• Sizing from steady LED watts and ignoring inrush, then wondering why a relay welds shut and the lights stay on.
• Putting too many drivers on one relay because the wattage 'looked fine.'
• A panel rated only for incandescent or resistive loads on an LED job.
• No override, so occupants cannot turn a zone off when the schedule is wrong.
• Mixing normal and emergency circuits on the same relay.
• Treating the cabinet as low voltage. The relays switch line voltage, and service belongs to a licensed electrician.

Shop relays on eBay

General buying advice only. This guide does not speak for any manufacturer, and it names no brands or part numbers. The shop is separate.

Related lessons

• Central vs Fixture-Level Control
• Line Voltage vs Low Voltage Controls
• Why Lighting Relays Weld Shut