5 Paralleled sets of 500 MCM, 3 Phase, what is the amperage rating good for?

If your pulling 5 sets of 500 MCM, you should be aware that the current rating will depend on the conductor material, insulation type, temp rating of terminations, quantity of current carrying conductors in raceway.

If not, then you should not be pulling these conductors.

All that has been taken into consideration. The insulation being used is THHN, each set of 3 phases and 1 neutral are pulled in 5 - 4' conduits. Therefore, I still need the combined amperage rating of all these sets paralleled.

OK, since you have taken all the specifc items I mentioned into consideration, and I still do not know all of them, all I can do is to suggest you must know what the amp rating of one set is, simply multiply by 5.

All I know so far by your information is there are 4 conductors with THHN in each raceway.

Copper or Aluminum?

Terminations temperature rating?

These two factors will dictate which column to use in Table 310.16.

Typically, assuming copper wire, and 75 Deg C column, #500 MCM is rated 380 amps, times 5 sets will total 1900 amps.

This assumes the neutral IS NOT current carrying. If the neutral will be for nonlinear loads, it will then need to be considered as current carrying, and the set of 4 conductors then need to be derated 80%.

This still does not take into consideration any ambient temperature correction factors from the bottom of Table 310.16.

So, as you can see, there are many factors to be determined to amperage rating of conductor, and with so little information given, I gave the answer of 1900 amps of what is a typical installation.

Based on the variables to be concerned with, I may or may not be correct.

All that has been taken into consideration. The insulation being used is THHN, each set of 3 phases and 1 neutral are pulled in 5 - 4' conduits. Therefore, I still need the combined amperage rating of all these sets paralleled.
Anyone asking this should have the education/experience to not have to ask. Especially on a "Home & Garden" message board.

What are you going to do with the information you get? Build the job? What if is it wrong, even by a little? What you are talking about is at minimum a mid 5-figure dollar job. Are you going to take a chance on a job like this?
Even a small mistake could cost you $10's of thousands.

Is this a homework question?