How to wire GM 40 timer to control DC voltage

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2012

How to wire Intermatic GM40 timer to control DC voltage

Intermatic timers and manuals

Overview of timer: Set dip switches BEFORE applying voltage:

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GM40 instruction manual
Sell sheet with model numbers

Set dip switches before applying voltage to timer

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Rating: SPDT; DPDT
Nema 3 indoor/outdoor enclosure
Mechanism sold separately
Up to 8ga AWG solid copper wire
Manual override on timer dial

120 volt; 208-240; 277Volt
Grounding lug for ground wire
NO contacts 40 amp resistive
NC contacts 30 amp resistive

1Hp 120V
2 Hp 208-240V

24-hour 15 minute timer
7-day 2-hour timer w/ skip-a-day
Backup battery option

	Wire GM40 timer to control DC motor: Use same diagram to control any single-phase voltage. Do not mix different gauge wires under same screws. Smaller wire comes loose, causing sparking and high heat and fire. Do not mix solid wire and stranded wire under same screw.

	240 Volt Wire GM40 for 240Volt water heater Basic 240Volt wiring Turns OFF both hot wires going to load
	240 volt GM40 controls two 4500 watt 240Volt water heaters Turns off 1 hot wire to each water heater Use 8 gauge wire to timer. 10 gauge ire to each water heater Timer not rated for controlling two 5500 watt water heaters
	240 volt GM40 controls two 240Volt water heaters One or other water heater is ON. Both heaters not ON at same time Use 10 gauge wire

	120 volt Wire GM 40 for 120Volt water heater vvv
	120 volt or 240 Volt Wire GM40 timer to toggle water heater between 120Volt and 240Volt. Use this technique for peak electric prices. When prices are peak, set water heater to opeate at 120 volts for slower heating. Tank stays hot, but hot water does not recover quickly. When peak price ends, resume 240Volt operation for faster heat recovery inside tank. Wiring inside water heater is not changed Elements and thermostas will work wirh 120 or 240 This will not work for Whirlpool energy smart water heater

Set the FM1 clock
Rotate dial until current time shows on clock face Larger image	How to set timers
Timer dial has switch located on right side of face, below the arrowhead. This is the manual switch. With the manual switch in middle position, the GM40 is in automatic mode and will switch at the programmed times. In the upper position "I", the load is permanently ON. In the lower position, "O", the load is permanently OFF	Move pins out for times you want DC motor to operate. All consecutive pins must be out for hours you want motor to operate. Manually rotate clock dial to watch when motor turns on. After pins are set, manually rotate dial until current time lines up with arrowhead located on inner dial.
Link for replacement timer modules Buy GM40 at 1000 Bulbs

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