Shocking Electrical Lessons Learned

Cody Fincher, PE, CEM, LEED AP / Aug 9, 2018

Through years of commissioning electrical systems, I have found many issues in the field that I found rather… shocking. Often, more surprising than the actual issues themselves are how often these problems occur. The following are four examples shocking electrical issues.

#1 Although you may set up a facility to operate properly at time of completion, this initial setup may not always work with your facility. Often times, the changes that are made to a building throughout its lifecycle will have great impact on its systems. I saw this occur once at a complex facility. The emergency power system did not operate properly due to not having various settings adjusted appropriately. The set points for the amount of load on the emergency power breakers were programmed based on when the facility was first completed, and were not adjusted when additional loads were added over the years. The project had recently installed a new generator so that there were three generators to be paralleled together during an emergency condition.

However, due to inappropriate settings the system did not operate properly during the first power outage. When the first generator closed to the switchgear bus, it tripped offline due to being overloaded. This is because the load that was transferred to the generator was much greater at this time than when the facility first opened. When the second generator then closed to the bus, it also tripped offline due to being overloaded, and the same happened to the third. If the loads had been added to the generators based on the correct load levels, the generators would have had the necessary capacity to carry the load. Instead, each one shut down because they were trying to carry the entire load individually. Keeping your building systems updated after changes are made is critical in keeping the building operating effectively and efficiently.

#2 Emergency lighting is required throughout a facility to provide paths of egress to allow occupants to safely exit the building. During a power outage, these emergency lights will remain illuminated to maintain light in the walkways. A common way to keep lights illuminated is by having batteries in light fixtures that are required to stay on. The shocking thing about these battery backed-up fixtures is that the batteries are often not hooked up! The contractor will install these special fixtures in the appropriate locations with the batteries, but sometimes the battery is left unplugged. Therefore, the lights are never able to provide light during an outage, even though extra money was paid for these fixtures. This can easily be tested by turning off the power that feeds the light fixtures, typically performed by turning off the associated breaker. If the battery light fixtures shown on the design drawings remain on (usually only at approximately 50% brightness), you can be sure that the batteries are connected. They should be able to stay on for 90 minutes.

#3 People often times try to get you to test systems and equipment by “simulating” an event. While this is sometimes all that you can indeed do, occasionally it proves to be an inadequate method. Once, I was testing a switchgear that would automatically transfer loads from utility to generator whenever there was a power outage. To simulate this outage, the undervoltage relay was “jumpered” to have a power outage. I was able to verify that the sequences of operations were programmed properly. However, when I pushed to have power actually removed from the building via an outdoor switch, the switchgear never detected that there was a utility outage, so it never transferred to the generator. It was discovered that the relay was bad and had to be replaced. If “simulating” had been the only method used to test, then during the first true power outage, this critical facility would have been “left in the dark.”

#4 Coordination studies are used to coordinate the order in which breakers trip during an overload or fault condition. The goal is to localize the event by having only the breaker associated with the event trip, instead of an upstream that affects multiple breakers, potentially shutting down large portions of a building. In order to achieve this localization, settings on the breakers can be adjusted to modify the amperage and timing of when the breaker trips. On new construction projects, consulting engineers specify the requirements of having a coordination study performed, which the electrical contractor typically has the equipment supplier or a third-party engineering firm perform. The person performing the study enters all of relevant project information into software, and determines how all of the breaker’s settings should be adjusted. This study, which requires a lot of work to get correct and finalized, lays out all of the specifics of setting up the breakers. However, if the actual breakers are not set in the field, all of the time, energy, and money used to create the study are wasted. People often state that “these settings were adjusted at the factory,” but that is typically not the case. It requires someone to read the study, interpret it, and physically adjust the breakers throughout the facility in order for the coordination study to be effective. This coordination is very important to a successful electrical system, and someone familiar with coordination studies and the facility should check implementation upon installation of the equipment or after the study has been completed.

This is just a sample of some issues I see with shocking regularity! When it comes to your electrical hookups, it’s important to be sure that everything is installed and adjusted properly. While it might be easy to let these things fall through the cracks, electrical issues have a way of coming back to haunt you when you need reliability the most. Don’t find yourself shocked by your electricity!