Case studies are an excellent opportunity to learn what can happen when grounding at a facility does not meet requirements. Southwest Energy Systems, LLC has had the opportunity to work with many companies experiencing problems in electrical systems that link back to a grounding fault.
In many cases, our engineers arrive at facilities that cannot replicate the failure that brought us to the company. Intermittent and random failures are often the case. An additional problem comes from assuming that a system was installed correctly, because the contractor was expected to know the requirements.
Arizona fire station case study
Southwest Energy Systems, LLC was called to a city fire station, which was experiencing electrical issues. The initial call did not relate the problem to grounding or a power source problem. The city built this facility using city-approved contractors and a city building inspector. On the surface, these credentials would appear to be sufficient for anyone concerned.
The fire station was situated within 300 feet of overhead lines, carrying 34,000 volts. The building also incorporated a metal roof. The layout of Arizona fire stations places fire trucks in the center of the building, with regular fire personnel on one side of the facility and the administration, fire chiefs and captains on the other. In this particular station, the administration area was closest to the overhead lines.
On various occasions, the fire chief or a captain would receive an electrical shock while taking a shower on the administrative side of the facility. The frequency was intermittent. The electrical shock was severe enough to knock the individual to the floor.
Of course, this brought an immediate response from fire personnel in the facility. When asked what had happened, the response was the individual received a large electrical shock — perhaps the shower head was energized. Not only was this met with disbelief, the theory was proven wrong. A voltmeter showed no electricity on the shower head. However, the problem randomly continued, and to different individuals using the shower. The city finally called us to investigate.
Southwest Energy Systems LLC, Testing Services
Our engineers tested every electrical connection and outlet in the building. We performed ground testing, and found that the electrical system, surprisingly, had an effective ground connection. So we continued our testing.
We ran electromagnetic field testing, because many levels of EMF are unacceptable. High levels of EMF create havoc with electronic equipment and radio devices. For example, we have worked with hospitals having issues with armbands used for newborn security. These bands set off an alarm when anyone tries to remove the infant from the hospital without authorization. When EMF levels interfere, the armbands can set off alarms for no reason. This results in a hospital lockdown and employees desperately searching for a stolen child.
While the fire station was not having issues with radio communications or garage door openers, the possibility still existed due to the location of the high-voltage lines. The EMF levels from the lines were not the problem.
The fire station was built with steel — instead of standard wood — framing. Our engineers determined that the contractor installed the main grounding conductor to the steel framing on this side of the building. Two simple mistakes were made in the process.
When the contractor made the ground bond, the paint was not scraped away from the steel. Paint acts as an insulator; it reduces conductivity. This meant that very little energy could dissipate through the ground connection.
The second mistake was that the grounding clamp used by the contractor was not, indeed, a grounding clamp. It was actually a flagpole clamp. Apparently, since it was made of metal and looked similar, it was determined sufficient. Grounding clamps are specifically designed for creating a ground bond. Using anything else is against building code.
Our testing revealed that the administrative side of the building was behaving like a giant capacitor. The metal drain in the shower was not grounded. The section would build static energy from the overhead lines slowly, and then suddenly release it. The individual in the shower would have one portion of his body grounded, but then reach up, causing the current to discharge, resulting in a large electrical shock.
Once discharged, the energy would have to build again to reach a discharge potential. This created the inability to duplicate the problem at will or receive results with regular testing. By creating a true ground bond, with the correct hardware, we were able to solve this unusual problem.
Southwest Energy Systems, LLC performs electrical equipment and ground testing, which allows you to make sure that your facility will not face these unusual and unpredictable problems that can shut down your facility or cause injury.