Step 1: Safety First!
This instructable is intended only for someone experienced and confident in wiring high voltages. Do not attempt to do this if you are not. Household current can kill or badly injure you if you who do not understand the danger.
Only the U451 relay contacts should be used for control/connection to 110V AC. The relay screw terminals are isolated from the other circuit connections. DO NOT touch the U451 when there is 110V AC present.