John Sayers' Recording Studio Design Forum Archive

I have two wallplates, each with 2 XLRs and 4 TRSs, to be connected in balanced-fashion via GEPCO 6-channel multicore. The run is 25 feet.

The GEPCO cable travels inside flexible metal conduit, and the wallboxes and plates are metal.

The GEPCO cable appears to include drains for each of the six channels, as well as an extra drain for the multicore as a whole.

I'm wondering how best to wire the drains. I assume the individual channel drains will be connected to "Pin 1" of the XLRs and the shields of the TRSs. But what about the extra multicore drain? Should I route that to each of the individual connectors as well? Or just to the metal box and conduit?

As a side question, I have easy access for tying the boxes and conduit directly to earth-ground. Should I?

Any advice would be appreciated.

Eric

I know this is an old thread, but will answer anyway.

Depending on the gauge of the cable, and the size of the connectors (XLR or 1/4" vs 3.5mm or some unbalanced connections), you can twist the extra copper shield w/ the drain wire. Especially if you want some extra strain relief on heavily used cables. For the smaller connections, you can just cut off the extra shielding (braided or foil) (BTW, I never solder foil, cut it off). Use shrink wrap to cover up the ends so they don't short on the inside (or for softer jackets, you can sometimes push it over the cut ends).

Yes, the drain/shield goes to pin one (XLR) or sleeve (1/4"). A majority of equipment is pin 2 hot, so I typically use the colored wire (different for each number in cable) in the multi-core as pin 2 or "hot" (XLR) or Tip (1/4"). And use the clear or black jacket (neutral one in each cable) as Pin 3 (XLR) or Ring (1/4").

As far as the ground...Yes. I believe the NEC code is to ground any metal conduit/boxes. (Don't quote me on that).

From all above I want to add If the EGC is not isolated, then yes, if must be bonded to the outlet box. If it is isolated, you must still have a regular EGC, and the conduit can serve this purpose.