Why Protect All Panels Fed by Emergency Generators?

In certain commercial facilities the 2104 National Electrical Code requires that a surge suppressor be installed on all panels fed by emergency generators.   The NEC recognizes that there is a need to protect the equipment fed by the emergency panel from surges or dirty power coming from the generator.  This is true whether there is a storm or other event causing loss of power and generator operation, or whether the generator comes on during its monthly testing (generators need regular maintenance and testing to be reliable).   Today’s custom homes have electrical and electronic equipment similar to the lighting systems and controls, automation systems, HVAC systems, etc. found in commercial facilities, so home electrical panels have the same need of protection from dirty power originating from the use of  generators.


The reliability of standby generators is dependent on their careful application, installation, testing, and maintenance.   However, even the best maintained generator can be stressed on start up.  Generators are tricky and in many cases don’t provide the cleanest power or a nice sinusoidal waveform that electronics need to operate effectively and sustain longevity. One reason generators typically produce such dirty or irregular power, filled with lots of noise and high-voltage spikes, is due to the current they create.   Most generators try to produce a specific frequency of alternating current (AC) by precisely governing motor speed. But, governor engine control is mechanical and not always subject to precise regulation, especially on cheaper generators or units that need maintenance.  This is why we hear many instances of generators killing the very equipment they were designed to protect.  In most cases by installing a quality surge suppressor with enhanced filtering on the electrical panel fed by the generator will protect all equipment on that panel from the dirty generator power.  Click here to see a sample design diagram of protecting a breaker panel using TPS model TK-TTLP-1S240-FL.


However, to further protect your client and their electronic investments, TPD recommends TTLP panel mount units for all critical panels inside a custom home.  TPD does not limit its recommendation to only electrical panels fed by generators.  TPD also strongly recommends that TTLP suppression/filter units be installed upstream from the automatic transfer switch.  Installing protection upstream from the ATS will protect the circuit boards and power supplies within the ATS.   If a surge were to knock out the ATS, the generator will not come on at all.  Click here to see sample design diagrams of protecting transfer switches.  Almost every custom home has critical electrical panels, and while they may not precisely meet the NEC definition of emergency system panels, they are critical to the operation, safety, and comfort of the home.  If any of the equipment fails that is fed by the panel, it will likely be an emergency that the homeowner must deal with immediately.