Underground service conductors between a transformer and a meter are protected against which currents?

Underground service conductors between a transformer and a meter are protected against which currents?

• A. Short-circuit
• B. Ground-fault
• C. All of these
• D. Overload

Answer: (D)

Underground service conductors from the transformer to the meter are protected by an overcurrent device sized to the conductor’s rating. That protection is specifically to prevent overheating from excess current during normal operation and overload conditions. While a short circuit or a ground fault would cause a surge in current, those faults are cleared by protection upstream or by devices designed to respond to such faults; the segment itself is primarily protected against overload. Ground-fault protection isn’t a typical requirement for this service-drop portion, whereas overload protection directly limits the conductor’s current to safe levels. So the protection focus for these conductors is overload.

Underground service conductors from the transformer to the meter are protected by an overcurrent device sized to the conductor’s rating. That protection is specifically to prevent overheating from excess current during normal operation and overload conditions. While a short circuit or a ground fault would cause a surge in current, those faults are cleared by protection upstream or by devices designed to respond to such faults; the segment itself is primarily protected against overload. Ground-fault protection isn’t a typical requirement for this service-drop portion, whereas overload protection directly limits the conductor’s current to safe levels. So the protection focus for these conductors is overload.