Grounding and Bonding

Effective grounding and bonding are important for agency, home, and field stations. For fixed stations, they are required by electrical code. Together they prevent several problems:

• Potential differences between devices that could cause an electrical shock
• Damage to devices from a lightning strike
• Current flow between devices that generates audio hum
• Common mode currents that can make electronic devices misbehave (reboots, loss of connectivity, etc.)

Grounding refers to making a low impedence connection to Earth ground. The connection to Earth ground safely routes potentially dangerous currents to ground.

Bonding refers to making a low impedence connection between all devices (antenna, radio, power supply, PC, network equipment, lightning arrestor, etc.) such that they all remain at the same electrical potential (voltage).

It is not sufficient to ground each device independently. At RF frequencies, the Earth presents too much impedance to keep the devices at the same potential. Proper RF bonding connects every device to a single short, low-impedence conductor, such as a bus bar, copper strap, or large guage wire. That conductor is then connected to Earth ground to ground the system, creating a “single point ground.” It should also be bonded to the building electrical ground.

Ground wires must be low impedance to provide the best possible path to ground. Use at least #6 AWG wire. #2 AWG is even better. Copper strap is best. Keep the length as short as possible. Minimize the number of bends. Where bends are necessary, keep bends to a minimum radius of 8 inches.