[Mikejr05]

Can I add a 220 line to an existing 30 amp dbl pole breaker with an existing 220 line. panel is 100 amp with 4 20 amp breakers and 1 30 amp dbl pole and 1 40 amp dble pole.

 

[ScottR]

Can I add a 220 line to an existing 30 amp dbl pole breaker with an existing 220 line. panel is 100 amp with 4 20 amp breakers and 1 30 amp dbl pole and 1 40 amp dble pole.

You could replace the existing 240V line with the new one on that 30A breaker, but you cannot attach both to the breaker at the same time, no. (Called double-tapping; generally not allowed unless the model of breaker is listed for it. 30A and up are [AFAIS] never listed for it).

If you have the space in the panel, you'd have to add a new breaker for the new line.

 

[Mikejr05]

well do I need to have 30 amp dbl pole or will 15 amp dbl pole work don't want to overload panel

 

[HouseHelper]

well do I need to have 30 amp dbl pole or will 15 amp dbl pole work don't want to overload panel

That depends entirely on what is on the circuit.

What are the other circuits?

 

[Mikejr05]

using line for ac window unit

 

[Mikejr05]

well only using line for ac window unit 220 plug , what do you recommend

 

[ScottR]

well only using line for ac window unit 220 plug , what do you recommend

What is the load of the A/C unit? (In Watts or Amps).

1 30 amp dbl pole and 1 40 amp dble pole

What is on those 2 circuits?

And are the 20A circuits all for lights and receptacles, or do you have any appliances permanently connected to those?

 

[Speedy Petey]

well only using line for ac window unit 220 plug , what do you recommend

OK Mike. Let's try this from the top.

You have a 240v-30a circuits and receptacle being used for an A/C unit. Correct?
You want to add another 240v receptacle to this existing line. Correct?
For what? What is the draw or circuit requirement?