Beechcraft Baron G58 Pilot Operating Handbook page 342

Section 7
Systems Description
Tie Relay by placing the left alternator switch to the BUS TIE
position. When the Bus Tie Relay is closed, the white [BUSES
TIED] advisory alert will be displayed. Other characteristics of
the Bus Tie system include the following:
1. With both alternators inoperative, and one or both batter-
ies selected on, placing either alternator switch to the
BUS TIE position will close the Bus Tie relay. If both bat-
teries are on, the left and right bus voltage will be the
average of the two battery voltages.
2. The Bus Tie relay is automatically closed when the
External Power relay is closed and external power is
applied to the airplane.
7-42
Model G58
May, 2015