Adding an Override Switch to an Existing Relay Installation

February 5, 2019
Tech Tuesday


The ability to manually override a load ON or OFF in a system is not only desirable for many maintenance workers, sometimes it is required. That is why Functional Devices, Inc. offers almost all of our products with an Override Switch option. If you are saying to yourself, “Self, I wish I had thought of that before I ordered and installed the RIB® for my load,” there is a way to make it happen without replacing that RIB® Relay.

Using one of our Prepackaged Switches in a Box, SIB02S, and a little extra wiring, you can say, “I HAVE THE POWER… to override my load as well.” The three diagrams that follow show how that would be accomplished using the RIB2401B as an example. Any Normally Open (N/O) contact from a controlled device can be wired in this manner.

In Figure 1, the SIB02S has been placed in the OPEN position. This prevents the Load from being energized, regardless of the control input to the relay. Even if the N/O contact of the RIB® were to close, there is not a path for the electricity to flow from the Source to the Load. With the switch in this position, it is now safe to perform maintenance or diagnostics to the equipment.

Figure 1: SIB02S in the OPEN Position

In Figure 2, the SIB02S has been placed in the AUTO position. This allows the Load to be energized with a control signal to the RIB®. When coil voltage is present, the N/O contact will close, and there is now a path for the electricity through the SIB02S and the RIB2401B. The switch would be left in this position for normal operation.

Figure 2: SIB02S in the AUTO Position

In Figure 3, the SIB02S has been placed in the CLOSED position. This allows the control relay to be bypassed, and the load is now directly connected to the Source. The ability to bypass the control device is beneficial in troubleshooting a system, because it helps to zero in on the problem.

Figure 3: SIB02S in the CLOSED Position

Check out for the products listed above and the other products we offer. If you have any questions, email or call our Sales or Support teams.

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About the Author

Henry Smith is a design engineer at Functional Devices, Inc. He has a BS EET obtained from Purdue University in 2014 and a lifelong interest in electronics. As an engineer at Functional Devices, he gets to provide Technical Support to our customers, from distributors to specifying engineers and installers.

Henry enjoys providing tech support, as it allows our company to assist at every level of our product’s lifecycle and exposes us to interesting and unique applications. While not every technical question is unique, even answering a simple question or providing someone with the information in a timely manner can go a long way to helping him or her meet a deadline.