What exactly is a 20 amp dedicated line?

You can have it both ways; a dedicated line can be used with both outlets, or you can break the tabs connecting the upper and lower outlets and have a seperate dedicated line to each outlet, giving you 2 dedicted lines. With a dedicated line, no other outlets are on the line except the one you will be using.

What exactly is a 20 amp dedicated line?

A line that is dedicated for a specific purpose.

A 120Vac 20 amp dedicated branch circuit consists of,
(1) Equipment grounding conductor
(1) Neutral conductor
(1) Hot conductor.

A true dedicated branch circuit does not share a cable or raceway with any other branch circuit/s.

How many receptacles are connected to the branch circuit depends on what was specified by the customer or manufacture of a piece of equipment.

A single receptacle could be specified.

A duplex receptacle.

Two duplex receptacles.

One duplex is quite common.....

What did you specify when you hired the electrician?

Note.
Per 2008 NEC code if a duplex receptacle is split and fed by two branch circuits the breakers feeding the duplex receptacle shall have a common tie handle so both circuits can be de-energized by one handle.

Jea48, do you know if it's Code to run a single 220v romex line consisting of 2 hots, 1 neutral and 1 ground into a single receptical box, with each hot powering a separate receptical and the single neutral and ground doing double duty for the two recepticals? I assume that each hot would be connected to a separate breaker in the fuse box. If Code, this would be an efficient way to run 2 dedicated lines with one romex run.

Of course, the polarity of each receptical would be inverse to the other if powered by the 2 hots.

WOW! I think that I bit off more than I can chew from the responses above. Thank you very much for all of the information.

Bifwynne,

Yes, it is called a multi wire branch circuit. (Two 120V separate circuits.) Not two dedicated circuits....

Not so good for audio equipment that is connected together by ics though.

In 2008 NEC required that multi wire branch circuits must be fed by a multi pole branch circuit breaker. Too many electricians were being killed from an open neutral....