We've recently purchased a hot tub that requires 220v and our panel doesn't have room to add the GFIC breaker. We have a seldom used wall oven that is 220v and I'm wondering if it is possible to share this breaker rather than upgrading to a 200amp service. Thanks.

You can run an extra box out of the main box to add a double breaker, or, sometimes you can fit mini breakers in the box to get more room. You could add the hot tub on the same breaker, but a hot tub stays on all the time and you could not run them together. I don't know why you don't want 200 amp service. Sooner or later you will probably need it. Make sure you re-tighten all screws in that breaker box because they loosen with age and cause fires. Check receptacles, too.