I need to take 2 30amp 110v breakers and make them 220v to run to separate breaker box

Can't be done. Just get a new two-pole breaker.

Stan, I'm a little confused by your answer. Why can't they be used? Some of the older installs just had a metal clip over the breaker arms so they were both tripped at the same time.

Because I guarantee you it will be easier for him to find a simple two-pole 30 than a handle tie.



Sorry, I Have a sore spot for SP 30A breakers.
IMO you should have to show proof of experience to even purchase single-pole 30's. They are the most under-needed, yet over-abused breakers going.
There are maybe two or three applications for SP 30's. That's it.
Most often I see them replacing a 15 or 20 amp breaker by handymen, hacks and folks who don't know what they are doing.

Also, a handle tie does not create a "common-trip" breaker. 90% of the time they will NOT trip at the same time. All it does is make it so that both handles will turn off at the same time, which satisfies the intent of the code in the instance of a feeder breaker.

Just to back up Stan, using handle ties to connect the handles of two breakers for a 240 volt circuit is not allowed, exactly for the reason he explains.

Thanks for explanation, Brian