How to ground a shielded interconnect

Hi guys,

I have some questions about how to properly ground a shield on interconnects. Hopefully someone out there can shed some light on to this conundrum! :)

The one thing I know:
- I should only ground the shield at 1 end of the cable to avoid ground loop, typically at the source end.

The many things I don't know:
Basically i'm not sure if in addition to the 2 signal carrying wires (positive/negative) should there be a 3rd wire running the whole length of the cable (called a drain wire or something?) which is then soldered to the shield at one end, or does the copper braid itself act as the "drain wire"?
Should there just be a short bare wire at one end of the cable, soldered to both the copper braid and negative terminal? It would act as a bridge to drain any signal being carried in copper shield. This would make more sense IF the copper braid itself acts like the 'drain wire' mentioned above...

I hope I explained my question well. If i can clarify anything please let me know.

Food for thought:
One thing I still don't get, if the shield is grounded onto one of the interconnect plug, how would it be possible for the shield to reduce noise? It seems that a shield is mostly reflecting unwanted interference, which in turn stimulates electron flow (ie noise/interference currents) in the shield. Then by grounding the shield at the negative terminal this noisey current is just redirected back to your signal carrying wire.
So isn't this the same as not having a shield at all? Just indirect interference, rather than direct.

I have a lot to learn, but it seems to me that an earth ground (solder a lead from the shield to terminate on a screw somewhere) would be the only way to siphon the noise from the copper braid shield...


Thanks in advance for your help!!
Anyone have any advice?
It's the components that need proper grounding to prevent ground loop, not the cable. RCA interconnects have no ground wire and XLR has that 3rd grounding wire. But that is to help protect against RF and EMI.
You mention Earth's your amp that needs it. And only one component should be earth grounded. Grounding more devices can lead to ground loop.
You have to understand how the shield works. Interference can be capacitively or electromagnetically coupled. In first case it is straight forward draining interference to ground. In case of electromagnetic interference lower frequency coupling is prevented by the cable lenght, that has to be 1/10 of wavelength to be an effective antenna and by the skin effect for the higher frequencies. Non-magnetic shield cannot protect against electromagnetic interference so interference is being induced but because of skin effect it appears on the outside layer - the shield. Equivalent field inside of the shield is zero. As for grounding - shield should be grounded at one end (but XLR shields are grounded at both) and every component that requires grounding should be grounded (in star fashion) to common ground point. That's pretty much safety requirement.

Electron flow does not play a part since electrons are not moving at AC (vibrating in place). Electric charge is moving back and forth but when it comes to delivering power it is not even by the cable but rather on the outside of the cable by electromagnetic field (called Poynting Field).