Small gauge ground wire, is it OK?

bought Audio Magic's Sorcerer 4D cable in bulk to make separate runs from my breaker box directly to the components. When I opened the ends of the Audio Magic cable there two big conductor lines separately insulated inside the foil shield. Each insulated bundle has 4 wires inside and should be around 6-8AWG in total. But to my suprise, there wasn't any ground wire visible, except a single run of a 20AWG insulated wire. I asked about it to Cable Company where I purchased the cable and they asked to Audio magic about this and they confirmed that small gauge wire is to be used as Ground. Somehow I'm a bit worried because I've always known and seen Ground wires to be around the same gauge of current carrying wires. Is this OK to use?
There should be little or no current flow in the ground wire, so a large size, while OK, is not necessary.
This "cable" doesn`t meet electrical code. In case of a fire, not only won`t you collect a thin dime from insurance, you`re 100% liable. Where`d you get this 1/2 brained idea?
Where`d you get this 1/2 brained idea?

You would be surprised how many cable companies out there are selling home made power cords, cables, that are not UL listed. Making your own is one thing, but selling them is another.
Wire that's rated for 15-amps must have a No. 14 ground and wire rated for 20-amps must have a No. 12 ground. Eldartford, even though you are correct that no current flows through the ground, it's purpose is to act as a secondary path back to the panel in the event of a fault. This is so that the circuit breaker can trip, protecting the faulted circuit. If you cannot reset a breaker, then you have a fault.

I don't know how you determined that the size is 20AWG. Even low voltage control wires are a minimum of 18AWG. Now, if the cable has a metal jacket, then that jacket is the ground and is perfectly ok. The thin wire, in this particular case, would be a bonding wire which completes the connection to the jacket ground. If the jacket is non-metallic, then anything less than 14 wire is not safe and in most jurisdictions illegal.

Check with an electrician or the local building department to be sure.
Gs5556...I was thinking only about how the ground wire might affect audio quality...not the trivial detail about burning your house down :-)
OK, the cable has a metal braided shield.Should this be used as a ground path? Should it also be connected at both ends (IEC and Breaker) to the ground terminals?
Eldartford, why sweat the small stuff, right?