Ampacity of a DC-Busbar

Easy. Enter "busbar sizing" into the Search all of CR4 box on the right of this screen.

Duplicate post? Busbar sizing has been tackled here many times, as the search will reveal.

Hint: Search for one of the many, many automatic calculators on the internet, if you can't understand the good advice of PWS.

How to Search the Internet Effectively

Or consult NEC/BS. Don't know what NEC/BS are?

How to Search the Internet Effectively

Came across this bus bar while travelling, it was highly amped, about 20' I think...

What would be the NEMA class of the enclosure? Washdown?

Class of '78..... Farfegnugen...

You're asked to design the DC-bus-bar for a 16,000 ampere furnace (I presume that's a cold start up current) and you don't know where to start or how to search the web for a clue. I hate to ask a slightly rude question, but I must. How did you get your job? Anything that consumes or transports 16,000 amperes of current should not be designed by an amateur.

Just do it. Go very conserative, no one will ever know but you.
If possible use one of the other furnances in your plant for reference.
At this current level there are mechanical forces, so brace everything.
Calculate the bus bar temperature rise. At DC it should be easy.
Build the bus bar to a written specification. If there is no written specification, write one and have your supervisor sign off on the specification with a signature.

I was told to design a 55,000 amp power supply and was recently out of college. Designed it. Of course there were problems but nothing major.

On a 1 off thing like this your supervisor should expect some unexpected problems and so should you. Don't get too excited if there are problems.