4th Connection on XLR cable (Accidentally deleted this post from earlier)

I posted this earlier and accidentally deleted it while editing a draft.

For those of you wondering what the 4th connection on an XLR cable is, it's called a "shield ground" in where the ground is connected to the entire metal casing of the cable.  It is usually not recommended to use this method being that once the cable is plugged into a system that has an alternate ground it may create an "earth loop."

Here's what one blogger had to say:

Why not to connect.

If you use the fourth lug you connect the metal parts of the connector to your “sound system earth”.  If the metal parts of connector then makes contact with something that has a different earth eg. lighting truss, metal parts of the stage etc. you have an earth loop.