My husband recently installed an over the range microwave. He had to rewire from the hood that was previously there, and put in an outlet. He says the oven is on its own breaker, and the microwave is on its own. The microwave works great, and the stove top works, all my burners can be on at the same time, however, when I try to preheat my oven it trips the breaker. I have a pretty old oven, so I don't know if the problem is the oven, or the wiring? I don't want to spend the money on a new oven unless I have to, but I don't want to spend the money on an electrician if it's the oven... Help!

If the oven has been connected the same fashion all these years and justed tripping the breaker, the problem is in oven