IEEE 242-1986

IEEE 242-1986 is a recommended practice for protection and coordination of industrial and commercial power systems. It addresses how protective devices and system settings should work together so faults are isolated quickly while service to the rest of the installation is maintained. In power, energy, and industry applications, that coordination matters because it can help reduce equipment damage, improve safety, and support more reliable operation across connected electrical distribution equipment.

About IEEE 242-1986

IEEE 242-1986 focuses on the engineering principles used to protect electrical power systems in industrial and commercial environments. It is concerned with coordination between fuses, relays, circuit breakers, and related protective equipment so each device responds appropriately under fault or overload conditions. As a technical document, it is useful when specifying, reviewing, or maintaining distribution protection schemes. The standard provides a structured reference for selecting and coordinating protection practices rather than leaving decisions to ad hoc judgment.

Where is IEEE 242-1986 used?

This standard is commonly used in facilities that depend on dependable low- and medium-voltage power distribution, such as manufacturing plants, large commercial buildings, and process-driven sites. It supports the design and review of feeder protection, motor circuits, switchgear arrangements, and transformer coordination. IEEE 242-1986 is especially relevant where multiple protective devices must operate in sequence to isolate only the affected part of a system. It can also guide engineering teams during upgrades, studies, and equipment replacement planning.

Importance in practice

In practice, IEEE 242-1986 helps teams make protection choices that are consistent, defensible, and easier to validate. Good coordination can reduce nuisance trips, limit downtime, and lower the risk of unnecessary damage during faults. It also supports clearer procurement and testing requirements by giving engineers a recognized basis for device selection and setting coordination. For owners and operators, following this kind of recommended practice may improve system reliability while helping manage safety and operational risk in electrical installations.

• Protection and coordination guidance
• Industrial and commercial power systems
• Device setting and sequencing review
• Fault isolation and continuity of service
• Superseded IEEE standard, English language