Standby instrument lighting is energized by power from the battery bus or the APU battery direct bus (Post SB 700-24-003 on Global Express) when the usual lighting power to the standby instruments is not there. Standby instrument lights are integral lights and are controlled by the center (CTR) integral lighting system.

The standby instruments lighting power supply is installed inside the right side console at FS260.00 on Global Express/XRS and at FS260.00+32.00 on Global 5000. It is identified as A178 or PS 3.

On A/C Pre SB 700-24-033 for Global Express, it has two 28 VDC power inputs: the battery bus through the secondary power distribution assembly (SPDA) 2, the DC bus 2 through the SPDA 1.

On A/C Post SB 700-24-033 for Global Express, or on Global 5000/XRS, it has three 28 VDC power inputs: the BATTERY BUS through the secondary power distribution assembly (SPDA) 2, the DC BUS 2 through the SPDA 1, and the APU BATT DIRECT BUS through a thermal circuit breaker on the ASCA and the BATT MASTER switch.

Its outputs are variable 0-5 VDC and multi-channels for individual instrument lighting. Each output circuit is protected against over-current by a device inside the power supply. Usual operation will automatically start again when the over-current condition is removed. The power supply output is controlled by the CTR BRT/DIM rotary control of the INTEGRAL lighting system.

On the COCKPIT LIGHTS (INTEGRAL) control panel are a MASTER ON/OFF/AUTO toggle switch and five BRT/DIM rotary controls. The panel is mounted in the flight compartment on the center pedestal. When the Master switch is in the ON position, a discrete ground signal is sent to the two EMS CDUs to set the integral lighting system on. In the OFF position, an open discrete signal sent to the EMS CDUs sets the system off. In the AUTO position, the light sensor unit supplies the discrete signal to the EMS CDUs which control the power to the integral lighting system.

There are five BRT/DIM rotary controls on the panel. The rotary controls send variable control signals to the integral-lighting power supplies. The integral-lighting power supplies change the intensity of the lighting.

Standby instrument lighting operates with the panel integral lighting system, and employs one of the eight power supplies. The DC power supply, assigned to the system, distributes variable lighting voltage to the standby instruments, guidance control panel and the EICAS controller panel.

The brightness is controlled by the CTR rotary potentiometer on the Cockpit Integral Lights control panel. Normally, the standby instrument lights are powered by DC Bus 2, SPDA #1. In the event that DC Bus 2 cannot be powered, the Battery Bus supplies power via SPDA #2, or APU BATT DIRECT BUS supplies power through a thermal circuit breaker on the ASCA and the BATT MASTER switch.