Originally Posted by AllanJ
You need a switch that will handle the amperes going into the panel eligible for generator power. For a whole house transfer switch this means 100 amps or more. For a transfer switch for a subpanel the switch ampacity would be at least that of the breaker for the subpanel. The switch must be able to break that load (tolerate an arc) as well as carry that load. Transfer switches generally have springs that open the switch very quickly which in turn means the arc upon breaking the circuit doesn't last very long and therefore doesn't generate as much damaging heat.
Contrast that with a small double pole double throw slide switch less than two inches long in the front of an amplifier and used to select DVD player versus X-box game left and right audio channels and be able to handle perhaps one ampere.
By the time you find a "simple DPDT switch" that handles the ampacity, you are looking at switches called transfer switches.
I think you need to get your facts straight
This is a DIY forum. People are interested in saving money and the contributors should recommend safe inexpensive solutions. Your broadbrush
comments would suggest that the most expensive solution is the ONLY solution. I am merely offering what I think is a reasonable design solution given the OP circumstances. PROVE IT WRONG.
1-The switch ampacity he needs is only 30 amps and any dpdt UL listed switch will handle the arcing and heat you are so worried about
This switch is rarely actuated so failure due to long term pitting of contacts is a non-issue.
2- I have used 30 amp dpdt switches in industrial applications years ago and they were less than 3 inches long
3-I have found a few by googling and if you are interested ,Surplus Center has one for less than $10. This doesn't mean I would recomend it.