Snap, crackle, no pop

Testing a 240V through wall AC/heat combo unit yesterday and the sub-panel began buzzing and smoking. Turning off the breakers and pulling the cover and I found this. The bottom split 20A breaker and the fourth pole up from the bottom control the AC. Is it a phase issue? These should be on opposite phases, yes?

They need to have a handle tie if acting as a 240 line at the very least. Refer to electrician , Not sure about phase issue but that could be an issue

Not to be a jerk, but there is no such thing as two phase electric. Only single and 3-phase. Normal residential 220/240 Volt is single phase.

The bottom CB (with white conductor) and the fourth one up from the bottom (the one that’s OFF) are connected to opposite buses therefore the voltage between them should be 240 volts.

I wonder if the oddball breaker on the bottom fits the panel. Perhaps improper bus connection.

I think CH breakers are okay in Crouse panels but I could be wrong.

Yes, standard residential 120 / 240 VAC single split phase system with interleaved bus bars. The two split breakers are on different buses, therefore the two 120V legs of this 240V circuit would be 180 degrees out of phase from each other, correct?

White paper

120-240 split phase residential diagram.png

The 2-20 amp CB’s (one ON, one OFF) on the bottom left are on the same stab. The next two CB’s (one ON, one OFF) are on the next stab or the opposite “phase”. Each 1" space is one stab, those factory two 1/2" breakers together occupy a single stab. If you look at the 2 pole, 30 amp CB on the right side you can see it’s on opposite “phases”.

Yes Robert, and the two OFF breakers (bottom, and fourth from the bottom) were feeding the AC unit. So they are on different bus bars and hence different phases. So the only issue with this configuration is the lack of a breaker bridge?

I wonder where the smoke was originating from. All looked normal once I let the smoke clear and pulled the cover.