If I fed a small sub panel.. is a 220 volt 30 breaker... 30 amps on each side or 15 amps on each side.. so if its 30 amps on each I use 10 ga wire... tks... richard

A breaker is what it says on the handle. You do not add them or divide them.
A 30A two pole breaker is just that, 30A @ 240V.
A 15A single pole breaker is 15A @ 120V, and so on.

And yes, typically #10cu wire is protected by a 30A breaker.

That's 220 volts 10 gage wire.. 30 amp breaker... is that 30 amps on each of my 110 lines ? Tks

Let's try it this way.

If you are feeding a panelboard with 2 ungrounded (hot) conductors without a Neutral conductor, the panel is a 240 (Line to Line or Phase to Phase) volt panel.

In order for you to have 120 volt branch circuits in this panelboard, you must also bring a "Neutral" conductor to the panelboard. 120 volt is derived by a Line to Neutral connections.

You cannot use a Line to Ground connection to create a 120 volt circuit.

Also, at the secondary panelboard, Neutral and Ground must be isolated from each other. You cannot connect a Ground conductor to the Neutral bar, nor can you connect the Neutral to the ground bar.

The ONLY place the both Neutral and Ground can be connected togerther in a residence is at the main service panelboard.

What exactly are you trying to accomplish with this second panelboard?

I am up grading a 220 volt 30 amp panel to about 220 volt 50 or 60 amp
I am looking for the wire now.. 6-6-6 is alunium OK ? It seens to be a lot cheaper... I seen some for 65 cents a foot.. 6-6-6 under ground...

How are you upgrading? What is the rating on the panel? Just because you put in a bigger wire does not upgrade it. Your posted questions concern me in seeing you do this as a DIY project.

I plan on buying a new panel rated for what I need.. about.. I don't know 60 to 80 amps.. maybe to be used with about 6-6-6 wire.. aluminum.. if its OK because it seens to be a lot... a lot cheaper... I know to use the no ox... I know how to do all this... just now sure about the wire sizes copper v aluminum... 150 foot run... I know about the bonding and lack of it... I was thinking a 12 or 16 space panel w/o a breaker just a 60 amp 220 volt from my main 200 amp box... and a disconnect at the sub panel... I am sure a wire rated 50 or 60 amps on each of the 120 volts sides will be plenty... your thoughts please... thanks for your time and concern... Richard
if you see it I posted the page for the wire...tks..

Products > Aluminum Building Wire > Underground Secondary Distribution Cable
Wire & Cable To Go offers Underground Secondary Distribution Cable at the best prices you'll find anywhere – available by the foot with no cut charges. Underground Secondary Distribution Cables may be used for underground secondary distribution and service entrance applications at 600 volts or less. They may be either directly buried or installed in ducts, in either wet or dry locations. Underground Secondary Distribution Cables are especially suited for applications requiring superior resistance to abrasion, scoring and crushing.

Underground Distribution Cable Product Selection

SOOW Cord 600V
Item O.D. (inches) Current Amps Price
6-6-6 Erskine Underground Distribution Cable » 0.650 97 $0.65/ft
4-4-4 Vassar Underground Distribution Cable » 0.744 123 $0.81/ft
2-2-4 Stephens Underground Distribution Cable » 0.830 160 $1.00/ft
2-2-2 Ramapo Underground Distribution Cable » 0.869 160 $1.05/ft
1/0,1/0 & #2 Brenau Underground Distribution Cable » 1.064 205 $1.50/ft
2/0,2/0 & #1 Converse Underground Distribution Cable » 1.170 233 $1.70/ft
4/0,4/0 & 2/0 Sweetbriar Underground Distribution Cable » 1.380 301 $1.90/ft
4/0,4/0 & 4/0 Monmouth Underground Distribution Cable » 1.460 301 $2.00/ft
250,250 & 3/0 Pratt Underground Distribution Cable » 1.530 329 $2.47/ft
350,350 & 4/0 Wesleyan Underground Distribution Cable » 1.720 395 $2.80/ft
500,500 & 350 Rider Underground Distribution Cable » 1.785 495 $4.80/ft