Chris Lewis wrote:


If such a thing were available in the US, that's probably Igor's
least expensive option.


His least expensive option might be to just use a readily available
transfer switch which is already tested and approved, commonly used and
quite suitable for the purpose.



CSA also lists certain engineering testing companies as approvers
in place of CSA. NEC probably does as well. Eg: Warnock Hersey.
But that's also largely intended for production runs, and it's
not cheap.