Circuit Breakers are designed to provide overcurrent protection for electrical networks and connected loads. Short Circuit Current protection is one such example of overcurrent protection and very often needs to be done in a coordinated way to ensure full protection at every level of the electrical network.
In protection coordination schemes, electrical designers may design the system as fully rated or series rated systems in order to achieve short circuit current protection. Understanding the differences between these two systems can have a significant impact on electrical safety considerations.
What is a Series Rated Protection System?
According to National Electric Code (NEC 110.22 and NEC 240.86), a series combination system is a system of circuit breakers connected in series such that a circuit breaker used on the network can have an interrupting rating lower than the available fault current, provided it is connected on the load side of an acceptable overcurrent protective device having an interrupting rating equal or higher than the available current on the line side of the device.
Under the code, manufacturers can publish a series combination listing only after they have tested these series combinations of devices under fault conditions to ensure it can safely clear faults and protect the equipment.
Advantages of Series Rated Protection
By using a series-rated protection system, you can save some bucks. Instead of upgrading the branch circuit breakers to costlier breakers that have higher interrupting capacities, series-rated protection provides an alternative. This particularly has a significant cost advantage in installations with very high available fault current.
However, this also means that the customer can only use a single brand of breakers for panel designs since there are no inter-manufacturer series-rated systems.
What is a Fully Rated Protection System?
Now, let’s switch gears and explore fully rated protection systems. The fully rated system is a more direct or traditional way of handling short circuit current protection.
In this system, every overcurrent device (main and branch circuits) is rated with interrupting capacities equal to or greater than the available fault current at the line side terminals of each device.
Advantages of Fully Rated Protection
- Enhanced Safety: With fully rated protection, they can rest easy knowing that the entire electrical system is equipped to handle the maximum fault current. By having both the main breaker and feeder breakers fully rated, the risk of equipment damage and electrical hazards is significantly reduced.
- Regulatory Compliance: In certain industries or jurisdictions, fully rated protection may be a requirement. It’s essential to stay informed about the specific regulations in the area and ensure the electrical system complies with the necessary codes.
Prevent Short Circuits with NOARK Components
Whether they opt for series-rated or fully rated protection, the key takeaway is the importance of electrical safety.
While series-rated protection can be a cost-effective solution, fully rated protection offers enhanced safety. Ultimately, the choice depends on their specific needs and circumstances.