Time out!!
The OP clamped a leg and got 70 amps! He does not remember the Peak KW demand from the POCO, but it was 'low'.
The 800 amp service is probably overkill.
Do we all agree:
That the CT equipment MUST stay?
The wiring of the transfer switch is explained above.
The transfer switch must be 800 amp rated IF the service is 800 amps.
PDH:
Our POCO here (NJ) would size the transformer based on load calcs submitted for the residence. 800 amp, single phase, 120/240 could be a 25-75KVA pot, pole mounted.
