Switchboard rules is critical for ensuring electrical safety and functionality. Proper construction techniques are essential for the protection and durability of electrical systems. This section covers essential aspects of switchboard construction, including access to live parts, suitability, clearances, and the orientation and location of fuses and circuit-breakers. (2.10.3 )
Access to Live Parts
Ensuring Safety
To protect against electrical hazards, live parts in switchboard construction must be shielded by enclosures, following the guidelines in Clause 1.5.4. However, in non-domestic settings, live parts may be exposed if:
Barriers are Used
Live parts must be protected by barriers that comply with Clause 1.5.4.4.
Controlled Access is Provided
Switchboards should be placed in areas accessible only to authorized personnel, with secure locking mechanisms.
If covers are removed and live parts are exposed, these covers must be clearly marked according to AS/NZS 3439.1 or AS/NZS 61439.1. This rule does not apply to domestic switchboards. (2.10.3.1 )
Proper access control and protection measures are crucial for switchboard safety. The guidelines ensure that live parts are either shielded or located in restricted areas to minimize risks.
Suitability
Durability Requirements
Switchboards must be built to withstand mechanical, electrical, and thermal stresses expected in their environment. Compliance with AS/NZS 3439 or AS/NZS 61439 series is required to meet these durability standards. (2.10.3.2 )
Switchboards need to endure various stresses throughout their operational life. Meeting established standards ensures that switchboards are fit for their intended use.
Minimum Clearances and Creepage Distances
Spacing and Safety
Switchboard construction must ensure that all bare conductors and live parts are securely fixed to maintain required clearances and creepage distances. These requirements are detailed in AS/NZS 3439 or AS/NZS 61439 series. (2.10.3.3 )
Exceptions:
• Reduced clearances and creepage distances are allowed for equipment meeting specific standards.
• The clearance between a neutral bar and earth can be reduced if the neutral bar is insulated from earth.
Maintaining proper spacing between conductors prevents electrical faults and short circuits. The exceptions provide flexibility for specific equipment while ensuring safety.
Orientation and Location of Fuses and Circuit-Breakers
Circuit-Breaker Orientation
Circuit-breakers should be arranged so that their mechanisms open the circuit when aligned in a general direction. Alternative arrangements are acceptable if they clearly indicate the off position. (2.10.3.4 )
Fuse and Circuit-Breaker Placement:
• Grouping: Fuses and circuit-breakers must be grouped to reflect their functions, such as for equipment like sump pump motors.
• Placement Restrictions: They should not be fixed behind the escutcheon where they cannot be operated, except in specific cases:
• Fuses: Can be placed behind panels if used as fault-current limiters or for protecting instruments/control equipment.
• Circuit-Breakers: May be mounted behind panels if they are operable from the front or used for similar purposes.
Proper orientation and placement of fuses and circuit-breakers enhance both safety and ease of use. Grouping and clear labeling support effective maintenance and operation.
Screw-in Fuses
Installation Guidelines: Screw-in fuses must be installed with the center contact on the supply side of the fuse base. This applies to fuses such as those in IEC 60269-3 System A Type D. (2.10.3.5 )
Correct installation of screw-in fuses ensures they function properly within the switchboard, contributing to overall safety and reliability.
We design and manufacture high-quality switchboards. Contact us today to discuss your requirements and get started!