GROUNDED AND UNGROUNDED SYSTEMS, MAKING A CHOICE

Not every electrical system needs grounding. Therefore, electrical contractors must know when to ground or unground a system. It is important to follow the guideline of the National Electric Code in this regard. Engineers and contractors must understand the advantages and disadvantages of grounding and ungrounding.

Why us grounding important?

Grounding offers protection against dangerously high voltage. This magnitude of voltage is caused by line surges and lightning storms. By grounding an electrical system, current is deposited into the earth where it is neutralized. It is not an uncommon procedure. In fact, it is common in residential, industrial, and commercial applications. During installation, mistakes can be made and this explains why electrical contractors and engineers are expected to adhere to NEC regulations. By doing this, safety is assured and mistakes can be avoided.

Types of faults

There are four types of faults that can affect the functionality of a system. They are arcing faults, line-to-ground faults, 3-phase faults, and phase-to-ground faults. In a 3-phase system, a line-to-ground fault is the most common type of fault.

Grounding systems

Grounding systems can be grouped into three – high-resistance grounding, solidly grounded, and ungrounded systems. Each of them has their advantages and disadvantages.

Solidly grounded systems: This is the most commonly used grounding system. In this system, the neutral cable is connected to the ground. It is very common in both commercial and industrial applications. There are two possible arrangement of solidly grounded systems – wye arrangement and delta arrangement. A major advantage of this system is that faults can be detected easily. It also offers more control over voltages. On the flip side, it often triggers high value fault currents which can damage an equipment.

High resistance grounding system: If continuous operation is your aim, you may want to consider a high-resistance grounding system. To achieve this, the neutral cable is grounded and this causes a reduction in the ground fault current. Its major advantage is that it can either be integrated or a stand-alone unit. It also shields electrical appliances from the effect of ground faults. Its disadvantage is that there is a chance of losing the neutral path.

Ungrounded systems: The NEC sometimes permits an electrical system to be ungrounded. In such a scenario, there is no grounded conductor but there must be a ground-detection equipment. A disadvantage of this system is that it makes it difficult to spot line-to-line ground faults.

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