Fit for Life? Avoid Equipment Failures

By February 14, 2022Conduit

Fitness centers are busy at the start of each new year as people renew their commitments to health and fitness with the help of sophisticated electronic equipment such as treadmills, exercise bikes, and stair climbers. One such facility contacted us desperate for help with repeated electrical problems, including variable frequency drive (VFD) failures, fitness equipment control screens locking up and requiring frequent reboots, and physical damage to electronic components requiring replacement.

Building managers frequently blame these types of issues on poor incoming power quality. They contact the electrical utility to fix the problems causing damage to their equipment. However, utilities are aware that while not impossible, supply-side power quality is rarely the cause of the problem. The culprit is typically inside the building, which means the utility will not be able to help.

HP&D’s Investigation

To rule out incoming power quality issues at this facility, HP&D began a site audit at the electrical service entrance equipment to verify the equipment was properly installed, grounded, and bonded. First, we connected a power quality meter to measure voltage, frequency, amperage, and harmonics. Then, we checked power quality at the distribution transformers feeding power throughout the building. With a handheld voltage meter, we also checked various receptacles in the facility. All measurements indicated acceptable power quality.

With power quality eliminated as the cause of the equipment issues, we turned our focus to grounding and bonding. We suspected the problems were related to equipment connections not being on an equal ground plane. The equipment experiencing issues had three services connected to each apparatus: electrical power, cable TV (CATV), and internet. When multiple services connect to a single piece of equipment, each service must have a common ground plane to prevent unwanted current flow through the control boards, especially during adverse electrical events like nearby lightning strikes.

Based on design documents and our visual inspection, we noted that some electrical rooms had ground bars connected to building steel while some had ground bars connecting back to the main electrical room ground bar. Additionally, some transformers were grounded to building steel while others connected to the ground bus. Further inspection revealed no CATV equipment connections to the ground bus, only to adjacent building steel in some rooms. The internet equipment racks and cable tray system were grounded to themselves and did not have connections to the room ground bus, and equipment with exterior grounding screws were not being utilized to ground the equipment.

All building systems need to be grounded to a common point to protect sensitive electronics from lightning strikes or voltage surges. The supplemental ground system (electrical room ground bars) attempts to do this by providing a more direct path to the ground than can be provided by the building’s grounding system. In this installation, having some building equipment connect to ground bars, others connecting to the main electrical room ground bus, some connecting to building steel, and others not connected to anything creates numerous opportunities for voltage potential differences to develop. These differences allow a surge, such as lighting, to use whatever path is available to equalize voltages. Lightning strikes dissipate their current through the earth. When this occurs near a building, current flow through the earth can create different voltages on the electrical service ground, internet, phone service, CATV, and building steel. In this case, the exercise equipment control panels become a path for equalizing the voltage differences, causing damage in the process.

HP&D’s Recommendations

To remedy this facility’s power issues, our recommendations included the following:

  1. In all electrical rooms, verify that an equipment ground bus is present and connected to the master ground bus in the main electrical room.
  2. Connect all cable trays, racks, and rack-mounted equipment to the room’s equipment ground bus.
  3. Where available, utilize ground posts in the back of equipment per the manufacturer’s recommendations.
  4. Verify that all supplemental transformer grounds connect back to the master ground bus.
  5. Test the building’s ground system resistance per IEEE Standard 81. This value should be less than 25 ohms per NEC (National Electric Code).

Applying Lessons Learned to Other Facilities

This case study happens to be a fitness center, but the issues they experienced are common to many facilities. With multiple services, including power, CATV, phone, and internet, plus a building’s grounding system, these utilities must be bonded together and connected back to a master ground bus at the building’s electrical service entrance. Otherwise, it’s just a matter of time before lightning strikes and damage occurs.