When working on a distribution transformer, the secondary should be completed last to eliminate the danger of ________.

• A. Parallel paths to ground
• B. Circulating current
• C. Static charge
• D. Back feed

Answer: (D)

Back feed is the risk here. When you’re working on a distribution transformer, energizing the secondary or leaving it connected while you’re still tying in or isolating other parts of the system can push voltage back through the transformer windings into the source side or upstream equipment. The transformer acts as a conduit between the two sides, so if the secondary is completed first, energy from that side can backfeed into the primary or feeders, creating an unexpected energization that can harm you or energize equipment you’re not ready to work on. Finishing the secondary last helps ensure there’s no live path back into the rest of the circuit while you’re completing the work, reducing shock and arc-flash risk. Other possibilities like parallel paths to ground, circulating current, or static charge aren’t the specific hazard addressed by this sequence.