Well a T in the plumbing sense wouldn't work. What you would need to do is put a junction box in at the point the split would be. Remember that anything underground (even in conduit) is a wet location so make sure your conductors and whatever else are rated for that.

The barn will most likely have special requirements as well. It sounds like with #6 you're planning multiple circuits out there. You'll need ground rods, appropriate disconnect, etc... You must run four conductors (two hots, neutral, and ground) to such a structure. Depending what's in the barn, there may be other requirements.

Tell me this jct box would it be located above ground on some sort of pole? would I use a pvc outdoor type?

It could be IN the ground for all it matters.

If there are no splices or other connections in the junction box, underground is OK.

"If there are no splices or other connections in the junction box, underground is OK."

Even if there ARE splices in the JB it can be underground.

It is just a little harder to make secure connections.

As I said, everything that's underground needs to be approved for wet locations. If you place the box in the ground, you can splice there but you have to use an approved splice (i.e., not regular wirenuts).

the wire insulation is marked rhh-2 and rhw-2. what does that mean? is it ok for underground in pvc conduit?

RHW-2 is 90C rated for both wet and dry locations. It should be OK.
There's no such thing as RHH-2 to my knowledge, just RHH (not that it matters here).

Note that you need to derate the ampacity of the conductors because you have more than three current carrying conductors in the same conduit. Of course, with 200+ foot runs you may wish to size up the conductor for voltage drop reasons anyhow.

Thanks for the info. I have #6 wire to run. Considering I will be making a 200 ft run with one set (3wires to power a 20amp gfi outdoor receptacle)and 4 #6 wires to power the barn with 220v,nuetral, and ground at a distance of 300ft. what breaker size will I need to use at the main box in the house for the barn run? My distances are more than I stated in my first post. My Bad!!! Thanks

What power requirements do you have in the barn?

The 20Amp GFCI will require a 20Amp beaker.

If your #6 is copper, then it has a rated ampacity of 75 which has to be derated by 80% to 60A. If it is aluminum, it has a rated ampacity of 55 which derates to 27.5 which you can round up to the next breaker size of 30A.

I have #6 copper to work with. The requirements for the barn are what ever capacity that wire will carry at 300ft. That's because I already have the wire stored from a few years back when a 250" roll of 14/2 with ground was $18.00!!! So I'll work with what I have. I can't even imagine what #6 copper RHW wire x 4 @ 300ft costs today. According to the above posting I can run 60amp at 300ft, so with 4 #6 conductors I would use a 2pole 60amp breaker at the main box. What if I dropped down to a 50 amp 220v circuit, what distance can I run then with this wire? Thanks

The ampacities have above have nothing to do with distance. It's the standard capacity for 90C wiring derated due to having more than three current carrying conductors in the conduit.

The amount of load you can run depends on how much voltage drop you can tolerate in the barn. Since it seems that the wire size is fixed, it doesn't seem like it matters. You still use a 60A breaker.

To compute the voltage drop you'll need the ACTUAL load drawn and the distance (and the #6) wire size. You can google to find several calculators that will let you know what kind of drop you're looking at.