What Are the Main Types of IEC Earthing Systems?
Various low-voltage earthing (grounding) systems utilized in electrical installations is the safest according to the International Electrotechnical Commission’s (IEC) definition of the basic earthing system types, especially IEC 60364.
Because they determine how electrical facilities are connected to earth to avoid electric shock & equipment damage, these systems are essential for safety.
Inspection of Every System according to the safe earth connection and the electrical current’s flow from the transformer (source) to the customer’s appliance (load):
1). Terra-Neutral Combined or TN-C
2). Terra-Neutral Combined-Separate or TN-C-S
3). Terra-Neutral Separate (TN-S)
4). Terra-Terra or TT
1). Terra-Neutral Combined or TN-C
How it Operates?
For the whole system, a single conductor (PEN) serves as both the Protective Earth (PE) safety function and the Neutral (N) return current.
Why it’s “Safe”?
Your home’s entire earth wire and all related appliance casings may get activated at full power if the PEN conductor breaks anywhere.
This poses a serious risk of fire and shock. Because of this, several contemporary electrical rules for fixed wire forbid its use.
2). Terra-Neutral Combined-Separate or TN-C-S
How it Operates?
At the building’s entrance, the combined PEN conductor which originates from the transformer is divided into distinct Neutral (N) & Protective Earth (PE) conductors.
Why it’s “Safe”?
Because of the separation, there is less chance that the casing may become live during regular operation because the safety earth (PE) inside the structure is independent of the neutral current.
Known as Protective Multiple Earthing, or PME, it is popular and reasonably priced.
If the upstream PEN conductor breaks before the separation point, there is still a slight risk.
3). Terra-Neutral Separate (TN-S)
How it Operates?
From the transformer to the customer, the Protective Earth (PE) and Neutral (N) are independent wires.
Why it’s “Safe”?
Neutral and the earth are totally separate entities. The safety of the earth wire is not directly impacted by an issue on the neutral circuit, such as a break.
Among the TN systems, this offers the highest level of safety and is utilized in crucial settings such as hospitals and manufacturing facilities.
4). Terra-Terra or TT
How it Operates?
The transformer is connected to the earth on its own. The earth electrode (similar to a ground rod) at the customer’s installation is separate from the neutral and earth of the transformer.
Why it’s “Less Safe”?
A local earth rod’s resistance may be very high. When a fault occurs, the casing may remain electrified because there may not be enough current flowing back to trip a conventional circuit breaker.
Safe (protected): A Residual Current Device (RCD/GFCI) is required for operation with this system. The device is extremely safe since the RCD quickly stops electricity when it senses any current leakage, such as via a person to local ground. It’s typical in rural regions.
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