Strong Monaco 20 Owner's Manual page 12

Your wiring should look like this. If wiring appears differently,
DO NOT power your spa and contact our tech support for assistance.
THREE WIRE
& GROUND
12
THIS SECTION FOR 220V SETUP.
STEP 5
220V
N
L1
L2
GRND
THESE WIRES GO
TO THE PC BOARD
CONTROL CIRCUIT