Cleeds,
At the main breaker the load is split, 2 separate bus bars each caring 120 volts. When you add a 30 amp double pole breaker you have 2 hots coming out, each hot out is 120. 30 amp double pole is like using two 15 amp singles, each single is 120. When add together that equals 240. You dont need to be on 2 separate bars to get this. the double pole breaker is on one bus bar using 2 spaces. I live in the US. Electrical is a hobby of mine for 25 yrs. I've have run electric for 2 ac in the past 2 yrs. I believe his wiring is correct or he would be popping the breaker. I believe the load is very heavy on one bus bar, which is fine. But he can balance it by putting the problem circuit on the opposite bus bar. When ac kicks on, the load will pull from opposite bus bar. Both circuits pulling loads from 2 separate legs. 240 come in at top of panel and splits, 120 each side. If this is new compressor it should have soft start built in. If not have a starter kit installed, but I would go first solution, balance. Good luck Pete