Safety in Electrical Switchboards

Three essential technical characteristics for the safety of operators working on electrical switchboards are highlighted: forms, IP rating, and mobility index.

These elements play a crucial role in protecting against electrical and mechanical risks. But how do these specific characteristics really help ensure worker safety and prevent accidents in high-risk environments?

Forms of Separation

What are Forms ?

Forms are partitions and screens that protect operators from live parts, such as energized busbars. They also prevent the intrusion of foreign objects and reduce the risk of arcing.

Types of Forms

• Form 1: No separation.

• Form 2: Separation between busbars and functional units. Available in variants 2a (outgoing connections not separated) and 2b (outgoing connections separated).

• Form 3: Separation between all functional units. Available in variants 3a and 3b.

• Form 4: Separation of the outgoing connections of each functional unit from other units and from the busbars. Available in variants 4a (outgoing connections in the same compartment) and 4b (outgoing connections separated).

Forms 4b, types 6 and 7, commonly used in England, allow safe intervention in the cable compartment by isolating power connections in an individual enclosure.

Ingress Protection (IP) Rating

Importance of the IP Rating

The enclosure of an electrical switchboard must protect against external influences and ensure protection against electric shocks, even with doors open. For example, in a data center, an IP31 rating (protection against foreign objects of 2.5 mm) is often sufficient.

IP Tips

Specifying an IP3xD rating can be useful: it prevents the intrusion of foreign objects of 2.5 mm while ensuring sufficient insulation distance against intrusions of 1 mm. It is essential to check panels and covers before energizing the switchboard to maintain the IP level.

Mobility Index

Choosing the Mobility Index

The mobility index determines whether an installation can remain energized during maintenance. This choice has a direct impact on operator safety.

Examples of Indices

• FFF (IS111): Access via a large door, full exposure of the operator.

• WFD (IS223): Disconnectable solutions requiring the disconnection of cables on the load side.

• WWD (IS233) and WWW (IS333): Safe interventions on a single module without touching power conductors, requiring fewer electrical skills.

Conclusion

Assurer la sécurité dans les tableaux électriques passe par une attention minutieuse aux formes de séparation, à l'indice de protection (IP) et à l'indice de mobilité. Ces caractéristiques techniques garantissent une protection optimale des opérateurs contre les risques électriques et mécaniques.