Distribution Boards (Metal)
All final-distribution enclosures shall be selected from the same range, rated for an incoming current of up to 250 A. Whatever the installation method (flush or surface mounted), they shall comply with Indian standards
The Distribution Board shall be of CRCA Sheet Steel for indoor installation. It shall be powder coated after seven tank processing .The degree of protection shall be
– IP30 for enclosures without a door.
– IP43 for enclosures with a door.
Enclosures used as Sub power distribution boards (MCCB incomer), Access to devices shall be protected by a door with a two-point closing mechanism guaranteed by the manufacturer.
For three phase configuration Distribution Boards shall have Per Phase Neutral Bars so as to give phase isolation in case of fault on any phase and suitable interconnecting wire sets with Insulated shorting Busbar for electrical isolation
Enclosures used as final distribution boards. The door shall be equipped with a closing system locked. Outgoings will be identified by labels affixed on front of the switchboard, at least 5 cm high, aligned with each device.
Common devices such as measurement and indication devices, pushbuttons, emergency off switches and socket-outlets shall be installed together in the same part of the enclosure and easily accessible to users. For enclosures equipped with a door, access to the above devices shall be possible without opening the door.
For cable entry enclosure should have detachable gland plates with adequate knockout holes of appropriate size and number shall be provided on top & bottom. Fixing screws shall have captive washers.
Enclosures shall be equipped with a removable chassis enabling cabling operations on a workbench, even if the back of the enclosure is already set on the wall. Chassis installation in the enclosure must be stable and functional even before it is permanently secured by screws.
In case of double door, the door shall be with spring loaded hinged & shall also be reversible in case of space constraints.
The shorting links ( Busbar) shall be insulated. The Neutral bars shall be insulated from the enclosure. The Distribution boards shall have two nos. of external Earth Stud (welded) to ensure better Earth continuity. Neutral Terminator shall be provided to terminate the Incoming Neutral in case of 3P MCCB as I/C.
It must be possible to install flush-mount enclosures without use of mortar. The front panels shall be perfectly seated, even if the rear part (flush-mount case) is imperfectly set or if the wall is irregular at the point of installation. Cement spill protector shall be provided with the enclosure so as to avoid dust & dart at the time of the construction.
It shall be possible for users to personalise doors without risk of touching live parts (non-transparent, transparent, images, wall paper, etc.). When a number of enclosures are installed side by side, with or without socket-outlets, the overall system must remain aesthetically and functionally consistent.
Suitable size insulated bus bars made of high conductivity copper and mounted on nonhygroscopic (FRLS) insulating supports shall be provided. Neutral and earth bus bar shall be with taped holes and brass screws spring washers, etc., complete.