🔍 Key Concepts

• Trace the AC power source feeding the battery charger on the one-line diagram (which switchboard section supplies it, and under what conditions it is energized). • Study the DC side around the 24 VDC battery banks, noting the two selector switches and the dashed line between them. • Consider how many batteries can be simultaneously connected to the charger and to the 24 VDC interior communications bus, and whether the same bank can do both jobs at once.

💭 Think About

• Follow the path from the emergency 120 VAC switchboard to the battery charger. Does the diagram show that this power is only available in an emergency, or whenever that bus is live? • Look at the positions of the two DC selector switches: in any given switch position, which battery is connected to the charger, and which (if any) is connected to the 24 VDC interior communications bus? • What does the dashed line between the two switch handles usually represent in one‑line schematics, and how does that affect which battery can be on charge versus on service?

✅ Before You Answer

• Verify which switchboard section (main vs emergency, 450 VAC vs 120 VAC) is feeding the charger’s AC input. • Verify, for each switch position, which single battery bank is connected to the charger output and which is connected to the load bus. • Confirm whether the switching arrangement ever allows the same battery bank to be both on charge and connected to the 24 VDC interior communications bus at the same time.