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Proper ground fault protection is required by the National Electrical Code, yet about 15% of ground fault protection systems tested by NETA (InterNational Electrical Testing Association) are improperly installed, contain defective components or don’t work correctly.
What is grounding?
Grounding or earthing of electrical equipment serves several purposes. The first reason is to ensure safety from overvoltages, faults and lightning. Grounding also provides stability of system voltages by providing a solid reference to earth and establishing a reference to control electrical “noise” that might interfere with the proper operation of electronic equipment.
Why is ground fault protection important?
A low level arcing ground fault can destroy switchgear in seconds, before the main service overcurrent protection kicks in. That’s because a 480/277 volt solidly grounded system has enough voltage to maintain an arc between one phase and a ground, but not enough current to cause a large main breaker or fuse to quickly clear the fault. The resulting arc is like an electric weld, consuming large amounts of metal in the seconds it takes the breaker or fuse to operate.
A properly installed and operating ground fault protection system will detect and clear the fault in milliseconds, fast enough to limit damage to acceptable levels.
Emerson can conduct a study of your grounding system to determine its effectiveness. Our Grounding Study analysis can detect problems such as:
- Neutral grounded downstream. Neutral bonded to ground in wrong location. Causes false or inadequate tripping.
- Incorrect current sensor installation and wrong polarity. Causes false tripping.
- Inadequate control power or connections. Causes lack of trip of the protective device.
- Failure to trip within manufacturer’s tolerances. Causes inadequate protection.
- To ensure the safety of your people and equipment, call on Emerson to perform a grounding study today.