I'm helping a friend with an audio installation, and he asked about the requirements for the microphone cable:
"Wiring Requirements: 2 Conductor shielded cable, 22 gauge with a 24 gauge drain wire.
The requirements imply that a 24 gauge drain wire is a necessity, but if the cable is properly shielded, is the drain wire a necessity? Other than providing some additional strength to the cable and/or an easy way to connect to and solder to the grounded shield, does it serve some additional purpose?
It is intended for an unbalanced electret microphone; I'm interested in other uses if not applicable here.
Best Answer
I think I've only seen drain wires in foil-shielded cables (but I could be wrong...). It is not possible to make a secure connection to the foil shield, so the drain wire is the only way to make the shield connection.
A drain wire is not required with a braid shield, as you can unbraid a bit of the shield, and twist the strands to make a "wire" that you can use to make a secure connection.