How far from the PBB does an RF Tx Cable entry have to be to require an Entry Point SBB?

• A. 10 linear feet
• B. 20 linear feet
• C. 30 linear feet
• D. 40 linear feet

Answer: (B)

The key idea is how far the RF cable entry is from the main bonding point (PBB) to determine where you must place a local bonding block. The PBB is the central point for bonding all RF paths to the building’s grounding system. When the RF TX cable enters the building more than 20 linear feet away from that main bonding point, you cannot reliably extend a low-impedance bonding path from the PBB all the way to the entry using just the existing run. In that case, a dedicated Entry Point SBB is required right at the entry to establish a proper, localized bonding path and keep RF currents from flowing through unwanted paths in the structure. If the entry is within 20 feet, the bonding can be effectively handled without a separate SBB at the entry.