Im installing a subpanel 100ap and my house main is 200ap?

Question

i went in my main box with a alm 100ap wire 2 hot 1 ground and in my sub 2 hot 1 ground wire . after i was done i tested my outlets they are 240 vt they should by 120 why i did some thing worng.

Answer 1

If you want 120 and 240V, you have to have 2 hots, 1 neutral, AND you HAVE to have the ground wire.  You should have a black, a red, a white and a green wire.  If you are putting the subpanel in a separate building, you also have to drive a ground rod and bond any metal water piping and structural steel to the ground wire.  If so, please repost on Monday and I'll answer any other questions you might have on how to do that.

Answer 2

You hooked one hot wire to one of the hot bus bars and the other hot wire to the return/ground bus bar.  This would do exactly what you describe.