If the PBB is not located in the equipment room, where should the cable tray be bonded?

• A. PBB
• B. SBB
• C. Equipment room ground
• D. RF Shield

Answer: (B)

Ground bonding should create a single, continuous path to earth for all metal structures, so any metal cable tray outside the equipment room needs a reliable bonding point that ties into the building’s overall grounding network. When the PBB isn’t located in the equipment room, the proper point to bond the cable tray is the SBB. This ensures the tray outside the room shares the same ground potential as the rest of the site, forming a complete bonding path back to the building ground.

Bonding to the equipment room ground would only connect to that specific space and might not maintain continuity with other grounded metalwork outside the room. Bonding to an RF shield is intended for shielding enclosures, not for general cable trays. Bonding to the SBB aligns the tray with the site’s main bonding network, which is the correct practice when the PBB isn’t in the equipment room.