Which is Better?
Well the answer is… it depends! But usually, the choice between the two control options becomes obvious depending upon how you answer the questions below.
But first, a definition or two may help. A relay is a simple switching device that uses a small signal to control a larger signal. In this case low voltage pulses open or close a higher voltage circuit. Think of a relay as a remote controlled switch. By electrical code regulations, each circuit has to be fed by and protected by a circuit breaker. Current travels from the circuit breaker, through the relay and on to your powered appliance. If you open the relay it cuts off the flow of current and your appliance turns off, if you close the relay it completes the circuit and the appliance turns on. So a relay panel adds on/off control to a circuit, but it still must be fed from a circuit breaker panel.
A controllable circuit breaker (also called a switch grade breaker, a smart breaker or a motorized circuit breaker), is a circuit breaker with a switch built in. It provides the electrical protection of a circuit breaker and the switching functionality of a relay in the same device. That means you have a single panel on the wall instead of separate breaker and relay panels. Obviously, a single panel saves space and cuts the high-voltage wiring costs in half.
Both solutions work well and are time tested. Each has a place where it is a better, more economical solution than the other. The question is which is best for you!
When should I use relays for remote lighting control?
Existing breaker panel
Do you have an electrical panel in place and is it up to code? If so, a relay panel probably makes more sense. If your panel meets electrical codes, simply add a relay panel in between your breaker panel and loads and you have circuit control. If you don’t have to upgrade your panel, don’t!
20 or fewer circuits to control
Are you upgrading lighting to LEDs and you only need to add on / off control to a few circuits? A small retro-fit relay cabinet is an excellent option. 4 to 64 relays along with low voltage control can be housed in a small enclosure that can be located in a convenient location near the circuit breaker panel. The smaller the circuit count, the more economical the relay panel solution becomes.
Only need to control single and two pole circuits
Relays can be used to control single pole 120/277 VAC and two pole 208-240 VAC circuits. Three pole relays are very expensive compared to three-pole controllable circuit breakers. Relay panels are most cost effective when you are managing smaller loads.
Available space to install relay panel
Up to 10 relays can be installed in a one-foot square indoor rated cabinet. Larger relay counts require somewhat larger enclosures. Sometimes there simply isn’t enough wall space to hang a new relay panel, so always check for space availability before making a decision.
Application only requires a limited number of on and off cycles
Relays are rated for 20,000 to 50,000 operations or cycles from off to on and back to off. This could be as little as 5 years under normal circumstances.
When should I choose controllable breakers for remote lighting control?
For new installations, or when your current breaker panel does not meet current code, motorized circuit breakers have a number of advantages over lighting control relays. Including on and off control at the breaker panel with remote controlled motorized circuit breakers in a project allows the following benefits:
Controlling up to 168 motorized circuit breakers
A single controller can operate switch-grade controllable breakers across multiple panels. This reduces cost per controlled circuit and allows control of circuits in different locations separated up to 500’ and at different voltages.
Need to control three pole circuits
Motorized circuit breakers are available in one, two and three pole configurations from 15 to 30 amperes and 120 to 480 VAC.
Greater cycle ratings than relays
Ratings up to 200,000 on, off, on cycles far exceed those ratings of lighting control relays. Mean time to failure ratings are 1.8 million operations. These are very robust devices.
Limited installation space
Combining circuit protection and on / off control saves as much as 50% of your valuable wall space. For additional space savings breaker panels are available in 84 position tall cabinets.
Tight installation labor budget
Including on / off control in the circuit breakers eliminates two wire connections per circuit as compared to installing circuit breakers and lighting control relays saving installation time and money.