• Ground has multiple meanings. It can be:

1. 0-V reference
2. Earth ground
3. Chassis ground
4. Analog/digital ground

• Floating means “-” terminal is not connected to the ground terminal. If a jumper is connected between “-” and the ground terminal, it is called grounded load.
• Shock hazard: metal chassis is used as return and not connected to earth ground. This may lead to leakage paths which result in high voltages. The solution is to connect the chassis to earth ground.
• Noise: if multiple ground paths exist, small potentials might cause voltage differences, which causes noises. The solution is to use single-point ground or equivalently ground bus.
• Sharing the ground return between analog and digital circuits may lead to noise because the switching current creates voltage spikes in digital circuits. It becomes noise in analog signal. The solution is to keep the grounds separated, and then attach them together at one single point.