What are the main types of grounding systems according to electrical codes?

The main types of grounding systems according to electrical codes are solidly grounded, resistance grounded, and ungrounded systems.

Solidly grounded systems provide a direct electrical connection between the grounded part of an electrical system and the earth, which helps to ensure safety by limiting voltages during fault conditions and providing a path for fault current. This type of grounding is commonly used in many electrical systems to enhance safety and equipment protection.

Resistance grounded systems utilize a resistor to connect the system to the earth. This limits the fault current during a ground fault, reducing the risk of equipment damage and allowing for continued operation even after a fault has occurred. This arrangement is typically seen in systems where maintaining continuity of service is critical.

Ungrounded systems, on the other hand, do not have any intentional ground connection, allowing them to maintain operation even during a ground fault. However, they can pose safety risks as fault currents cannot be effectively managed without proper grounding.

These characteristics make B the correct answer, as it encompasses the standard classifications defined in electrical codes related to grounding systems.