1. Busbar trunking shall have tap-off positions where shown on the drawings.
2. Each tap off position shall be provided with automatic safety shutters to shield the live busbars where the position is not occupied with a tap off unit.
3. Tap-off positions shall be non-flared and suitable for tap-off units to be plugged on to the busbars.
4. Shutters shall be activated by the insertion of the tap-off units and will only operate if the boxes are the correct way round.
5. The plug in contact shall self align with the busbars and plug-in openings shall provide personal protection and safety of IP 2X when in the open position and IP54 in the closed position in accordance with BS EN 60529.
6. Within risers, plug-in tap-off positions shall be provided with a maximum distance of one plug-in opening for each 1000mm.
7. Tap-off boxes shall be constructed of zinc plated sheet steel and shall be complete with hinged lids with an ASTA certified protective standard of IP54.
8. The tap-off boxes shall have circuit protective devices as applicable and shown on the drawings with mechanical interlocks to prevent tap box removal unless the mechanism is in the off position.
9. Where tap-off boxes are inserted into live busbar trunking, they shall be designed and constructed so that the current carrying metal parts are not exposed during the insertion and removal of the boxes.
10. The tap-off box shall remain earthed during removal, until all live connections are disabled. The tap-off box shall ensure that the box can only be inserted to give correct polarity.
11. All operational handles shall be pad lockable.
12. Tap-off boxes up to 630A shall be of the plug-on type for ease of installation and removal.
13. The tap-off units shall be MCCB current limiting type. The MCCBs shall compliment those used elsewhere (for the distribution panels) in order to allow co-ordination and future addition of shunt trip/motor operation devices.
