Since 1978, ground fault protection system testing has been required by the National Fire Protection Agency (NFPA) and was subsequently added to the National Electrical Code (NEC) for the purpose of personnel safety and prevention of equipment damage.
What is a ground fault?
A ground fault is an electrical malfunction that takes place when a current carrying conductor suddenly, and unintentionally, is given a path to ground through a conductive medium. This results in the grounded conductor getting to the same potential as ground and current flows along an unintended path back to its source. Unless this condition is interrupted, this can result in three phase equipment running “single phased”, flash-over resulting in a fire, and personnel injury or death.
How do we protect equipment from ground faults?
Although circumstances outside of our control make it impossible to completely prevent all ground faults from ever occurring, it is possible, and required by the NEC on certain systems depending on voltage and current, to provide a means of detecting ground faults and a means to interrupt them if they occur. The NEC states that when a ground fault protection system is required, the ground fault current must be limited by the protection system to 1200 amps. The NEC provides additional information on when these systems are required to be in place, the allowable location of the ground fault protection system, sizing requirements, and testing requirements.
What testing is required by the NEC?
While there are different types of ground fault protection systems, first it is important to know when you should expect to see a ground fault protection system in service so that you can anticipate the need to have it tested. Per NEC section 230.95, ground fault protection systems are required on wye-connected services greater than 150 volts to ground, but not exceeding 600 volts from one phase to another on any service that is rated above or equal to 1000 amps. Testing in accordance with NEC section 230.95(C) requires that the ground fault system is tested in the field when it is first installed on site and before the electrical service is energized for the first time. These reports are then provided to the authority having jurisdiction (AHJ) and are scrutinized as part of a pre-energization inspection. Note: NEC section 517.17(D) governs requirements for ground fault protection systems in health care facilities.
What can Mantis Electrical Testing LLC do to help?
Mantis Electrical Testing LLC will provide a skilled, highly qualified Test Engineer to test your ground fault protection system in accordance with NEC requirements and manufacturer’s technical publications as well as Institute of Electrical and Electronics Engineers (IEEE) and (Inter)National Electrical Testing Association (NETA) guidelines to ensure proper operation, installation, and timing of the ground fault protection system. This will involve providing a high current, low voltage source through the interrupting device to verify the trip pickup as well as current transformer polarity and installation of the main bonding jumper and neutral disconnect link. These tests are inexpensive and usually only take a couple of hours to complete from start to finish.
Call or click today to schedule your ground fault protection system functional performance test and remain compliant with NEC requirements.