What is interlocking?

In Blog, Maintenance Tips by Ed Miller

Interlocking is typically connecting (slaving) one piece of equipment to another piece of equipment’s main electrical shutoff often with the utilization of a contractor or other means.

Over the years I have seen numerous incidents in pump rooms that could have been avoided if the equipment installers took their time to read the installation manuals, and follow the electrical requirements outlined.

So why do we interlock the main power on certain equipment to the circulation pump? In pump rooms where chlorine systems, generators and UV are present, interlocking not only protects the equipment, but it protects the pump room from possible water damage and avoids any personal injury situations. You might ask yourself well what does interlocking have to do with damaged equipment, possible water damage and injury. 

Let’s say you have chlorine generator that is not interlocked and with no means to shut itself off if the main circulation pump is shut down, Hydrogen gas can build up to the point where either the plumbing fails, and or the chlorine generator cell itself fails due to extreme pressure from this hydrogen gas build up.  

Even if the chlorine generator is connected to a chemistry controller and or a flow switch either of which can fail, interlocking with the main circulation pump can almost guarantee you will never have any of these issues mentioned.

With UV systems a simple thermal switch is often used to shut down the lamps in the event flow is ceased through the main reactor housing, these switches are also prone to failure, interlocking with the main circulation pump protects the reactor housing & entire system from a overheat event.