What is the maximum permissible time for ground operations with DC power only to protect CRT displays?

• A. 3 minutes
• B. 5 minutes
• C. 7 minutes
• D. 10 minutes

Answer: (B)

Managing stored energy in CRT circuitry during ground operations with DC power involves limiting the time you keep the device grounded to allow capacitors and high‑voltage sections to discharge to safe levels. Five minutes is the maximum because it’s long enough for the residual charge to drop to a safe threshold, reducing the risk of electric shock or arcing when you touch exposed circuitry, while not delaying maintenance longer than necessary. Three minutes may not give enough time for a full discharge, leaving hazardous voltages present. Longer periods, like seven or ten minutes, are unnecessary given typical discharge rates and would simply slow down the workflow without adding extra safety in this scenario.