A. I would never add on to an old armored-cable system. A ground wire has been included in armored-cable wire for only the last ten years or so, which means you could be dealing with an ungrounded system. Better to leave the old system to itself and make all your work new and safe. When you disconnect old circuits, it’s important that you make them unavailable for connections in the future (Figure 1). Remove exposed sections of wire to avoid future use or confusion when tracing other wires. This will also make for a cleaner job.

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