I want to install a 300amp t from the main panel this is a commercial . What gauge and type of copper wire and what size conduit whould I use.

And what if I told you #2 in 4 inch conduit? Would you believe me?

Where is this located?

Phase?

What type conduit?

Location of conduit?

Are you an electrician?

Commercial what? Elaborate on the building.

Why would you tell someone #2 in a 4 inch conduit... I mean if your going to with someone... just tell them to pound sand or something. Don't intentionally give them the wrong information... even if its in the form of a question. That's dangerous and stupid.

Oh and by the way... its 350 kcmil in a 2 1/2 inch conduit for the average commercial installation into a 300 amp panel.

Since when is information in a question providing that information?

This is not Jeopardy. In my world a question does not provide information.

My point is a generic question was asked with a great deal if detail missing. And my other point is that anyone installing a 300 amp commercial feeder better have some knowledge and experience.

I am glad your able to speculate on the details that were not provided.

If it is single phase, and 4 - 350 MCM copper THHN/THWN can fit in a 2.5 " PVC Sch 40, the 3- #350 MCM and 1 equipment ground will fit.


If this question involves 3 phase, then what?

If Sch 80 is used, then only 3 # 350 MCM THHN/THWN will fit.

Assuming you know all the missing details and situations is dangerous.