Here’s a very good question from our readers, “Do surge protectors work when turned off?” It would seem logical to think that when a surge protector that is plugged into the wall would not function if in the off position and would thus expose your electronic gear to all kinds of surge damage; but this, in fact, is not the case. As long as your surge protection device is properly grounded, whether in a wall receptacle or inline as with a coaxial device, then all outlets and equipment running behind the surge protector is guarded.
However, certain functionalities of a device that require it to be turned on may not work, as with some surge protectors that have master outlets that cut power to all but a few designated outlets while leaving others on standby. This is usually the case with a strip-based surge protector. The passive redirect will still block potential surges in the off position.
Now is it a good idea to turn your device off? Why would you run the risk of endangering your equipment by turning off your surge protector? Does it have functionalities that would benefit you to keep it running? It’s always best to leave a surge protector running and in the on position. Unless of course, there is nothing plugged into it. But then you would just unplug it and sue it when needed.
With most modern electronics, the delicate microprocessors are too sensitive to handle surges. This is unlike electronics of twenty years or older. Back then, there were still surges but the equipment didn’t utilize the small computer components of today’s technology. Most modern electronics require a small percentage of continuous power running through them so that the tiny computers will stay active.
This is especially the case with home theater equipment. Most of these systems are designed to run off five volts of electricity round the clock. Hopefully you have your system plugged into a home theater surge protector of some kind and that it too is always running. One of the major causes of component failure after surge damage is constant rebooting. Another component that requires a steady stream of electricity is a cable box or satellite dish. These units are sent constant updates several times a day.
With MOV surge protection, the surge load is carried on the outlet side of the protector so that is hit first. Being a semi-conductor, a metal oxide varistor doesn’t require a current to function. So, do surge protectors work when turned off? Yes, but you should keep then turned on as long as they are functioning properly.