The GTD20A uses an internal relay contact to control the AC power feeding the lighting load. When the generator (or
central inverter) supplies AC power to the lighting fixture, the GTD20A bypasses the local switching means or dimmer.
This ensures the lighting load will be energized at full lumen output during generator (or central inverter) operation
regardless of switch position or dim setting.
No routine maintenance is required to keep the GTD20A functional. However, it should be checked periodically to
ensure that it is working properly. Note: Make sure to disconnect both the normal and emergency panel circuit breakers
before servicing.
! REFER ANY SERVICING INDICATED BY THESE CHECKS TO QUALIFIED PERSONNEL !
STEP #3
FOLLOW-UP & QUICK TEST OF THE INSTALLATION
> Mark each designated emergency lighting fixture with the warning labels provided (20 labels are provided
with each unit).
> Apply AC power to all circuits. The green "Normal Power Present" and the red "Emergency Power Available"
LED's should be illuminated.
> Perform a quick test as described on the unit label to check for proper operation. When the test
button is depressed, the green "Normal Power Present" LED should extinguish and the controlled
lighting load should illuminate regardless of the local switch position provided emergency power is
available (check red LED).
> During a quick test using a GTD20A with a dimming system, the lighting load should illuminate at
full lumen levels when the test switch is depressed regardless of the lumen level during normal operation.
> The entire generator (or central inverter) system, including all designated lighting loads, should be
exercised to ensure proper operation (e.g., power up the generator, throw the main automatic transfer
switch to the generator position, and check the lighting loads to verify they are operating properly from
the generator/central inverter supply).
OPERATION
MAINTENANCE
6
ILLUSTRATION 9
WIRING DIAGRAM for UL 924 - SWITCH BYPASS Applications
INSTALLATION
4 5 6 7
1 2 3
NORMAL
CKT BKR
PANEL
SWITCHED
HOT TO
DIMMING
DRIVERS
NEUTRAL TO
DIMMING
DRIVERS
EMERGENCY
CKT BKR
PANEL
1 2 3 4 5 6 7
DIMMING
CONTROL
GTD20A
ELECTRONICS
COVER
T1*
GTD20A TERMINAL BLOCKS
T2*
HOT
PURPLE
HOT
NEUTRAL
SWITCHED HOT
NEUTRAL
* WIRE GAUGES FOR ALL LEADS
TERMINATING AT T2 SHOULD BE #18 AWG.
* JUMPER CONNECTIONS ON T1 AND T2 ARE
CONTRACTOR INSTALLED.
TO DIMMING
DRIVER
PURPLE
CONNECTIONS
(0 - 10VDC)
TO DIMMING
DRIVER
GRAY
CONNECTIONS
(0 - 10VDC)
BLK
BLK
GRAY
WHT (IF PROVIDED)
GTD20A as a Switch Bypass Device with a 0-10 VDC Dimming System
