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Photos of WH40 timer/ same as T100 series timers
More Intermatic timers and manuals
T101M T104M201
Mechanism only                             Mechanism with fireman switch

To replace mechanism
Turn power OFF
Take photo of wires
Remove plastic insulator covering wires
Disconnect wires from timers
Push thumb spring located top left side inside box
Thumb spring will release mechanism
Tip mechanism out and lift upward to remove

T101M 120V SPST
T102M 208-277volt SPST
T103M 120V SPST
T104M 208-277V DPST
T104M201 same as T104 except with fireman switch
T106M 208-277V with NO NC terminals
Release timer from box using thumb spring

Never assume power is OFF
Use non-contact voltage tester on timer, on wire, on outlet to see if power is present.
Press button on tester, if single beep then no power is present. If continuous beep then power is present.
Never stand on bare ground, always stand on dry boards, do not hold or touch anything metal when working on timer or water heater that has power, tape tester leads to wood sticks, never touch wet water heater, or flooded water heater, or timer that had a short or fire without turning power OFF.

Buy non-contact voltage tester
Electric testers

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How to test is water heater electricity is OFF
WH40 timer How to set and operate
When insulator is installed, it is safe to touch inside of timer.
Always keep door closed to avoid fire hazard from sparking.

How to set and operate T100 series timers

        WH40 timer
Larger image
WH40 timer /has override on front of timer
Override lever clicks back-and-forth as trippers turn water heater on-off.
If you move manual override lever, then regular timing schedule resumes at next tripper when the tripper moves override lever.

WH40 timer

Wire color can vary
More wiring diagrams
How to wire water heater thermostats
Troubleshoot electric water heater
Off-peak ideas
See inside main breaker box
Difference between 120V and 240V
Convert water heater to 120Volts

Change WH40 into 120Volt timer
Change clock motor from WG1573 to WG1570
Larger image

240V clock wires from back of timer connect to terminals 1&3
156T1978A tripper
WG1573 clock motor
Basic wiring diagram:
Intermatic WH40, T104, T104-20, T174
 208-240 Volt timer
WH40 manual
How to wire WH40
Same wiring at T104 series, T174 series, and Pool timers: T104R3, T104P201, T104R201 etc.
Intermatic pool timers

How to set and operate T100 series timers
Trippers and parts 
WH40 wires identical to T104 timer
How to wire T104 same as WH40
T104 208-240 3-phase   208-240V
Larger image 208-240 volt 3-phase
WH40 controls 3-phase
WH40 controls 3-phase
How to wire 3-phase timer
What is 3-phase electricity
Choose wire and breaker size
Color code and amp ratings for wire
Figure volts amps watts for water heater
Pointer is stationary and points at 6:00 position
Store extra trippers on dial by putting 2 off trippers next to each other

Minimum on-off 1 hour because of tripper thickness
156T1978A tripper
WG1573 clock motor
How to set and operate WH40 timer

Off tripper pushes lever.
On tripper pushes same lever other direction
Lever is also connected to override lever.
Override lever snaps back-and-forth each time tripper moves lever.
Trippers are softer metal than lever.
Trippers are designed to wear out so timer lasts decades with replaceable trippers and clock motors.

15 minute delay
Trippers rotate around on the dial.
After the tripper moves the lever, then the tripper is still blocking the manual override lever from moving to another position until after the tripper rotates out of the way.
This takes 15 minutes.
damaged intermatic timer
Tripper lever can become worn.
Remove yellow dial.
Inspect the point where tripper hits the tripper lever.
Ideal conditions the tripper wears out before the tripper lever.
But if grease is allowed to dry out then the lever can wear down before the tripper.

Symptoms of this problem would be timer not functioning after new trippers are installed.
If the trip or lever is worn down as shown in photograph then a new timer needs to be purchased.
The trip lever is not sold separately.

T100 series timers
Trippers for Intermatic T100 series
156T1978A tripper
2 sets ON and OFF trippers
Trippers are softer metal and are designed to wear out without damaging timer.
156T1978A set 2
Intermatic trippers
WH40 timer Maintain WH40
Noisy operation, and prolong life of timer

Clean with compressed air
Apply white grease on tripper lever & gears
Turn off power, and spray flammable WD40 on gears to lubricate

White grease

Intermatic timer remove yellow dial Yellow dial can be removed
Remove yellow dial by removing 6-32 x 1/2" screw using size T-15 star screwdriver bit.
Remove spring, and add bit of white grease to spring where it rotates against pointer.
Move override lever to ON position.
Yellow dial lifts off of center shaft.
Add bit of white grease to outside of center post..
Motor gear rotates small gear, and small gear rotates big gear attached to yellow dial.
Yellow dial rotates around center post.

Clean timer:
Turn off power, pull timer out of box, Clean out timer with compressed air, and spray WD40, add a bit of white grease to lever where trippers make contact
Back of wh40 timer Back of WH40

When the override lever clicks, the lever directly moves a slide bar located on back of timer that mechanically opens-closes electrical contacts. Closed switch mean light bulb is ON. Open switch means light bulb is OFF.
T100 series design ensures that brass contact points cannot stick or arc-fuse together
Another image
Plastic gears
will strip out before damaging metal gears of timer mechanism
So timer lasts many years, and clock motor can be replaced
WH40 clock motor and gears WG1573 clock motor can be replaced
How to replace Intermatic clock motor
How to troubleshoot Intermatic timer
Intermatic replacement parts

Maintain WH40
White grease on override & gears
Clean with compressed air
Turn off power, and spray flammable WD40 on parts to lubricate
WG1573 clock motor
Look for clock number
WH40 clock motor
Consumes 3 watts power
WG1573 clock motor can be replaced
Star screws
3 watt consumption = 26,280 watts per year = 26.28 Kwh per year @ .12 = $3.15 operating cost
60 Hz for US market

Buy replacement clock motor for WH40:
240Volt WG1573

How to replace Intermatic clock motor

Adapt WH40 to different voltages:
Buy clock motors:
Change Intermatic timers by changing clock motor
Change WH40 into 120Volt, 24Volt, 480Volt, etc by changing clock motor
Applies to T104, T174, WH40, pool timers etc
WG1573 for 60 Hz 208-277V  WG1573 208-240Volt
WG1570 for 60 Hz 120V  WG1570 120Volt
WG1576 for 60 Hz 480V WG1576 480Volt
CW1570 for 60 Hz 24V CW1570 24V at Aplus
WG1571 for 50 Hz 120Volt  WG1571 motor for 50 Hz 120Volt
WG1574 for 50Hz 208-277V WG1574 motor for 50Hz 208-277V Amazon
Intermatic 156T1978A tripper
Buy trippers
156T1978A set 2
156T1978A trippers
PA115 - 25 sets
Timer dial can hold 12 sets
1 on- 1 off for each 24 hour period
124T1952 Insulator
Larger image
Insulator/ translucent
124T1948 single pole T101, T102, T105

124T1952 double-pole T103, T104, T106

How to install insulator
Insulator/ pdf
T101M mechanism only
Cheaper to buy new timer with box
Buy T100 series
Buy T100 series Pool
T104M mechanism
T104M201 mechanism
124T2411A insulator pk 25
Insulator/ black rigid
124T2411A  rigid pk 25

How to install insulator

How to install insulator
Insulator/ pdf
Old WH40 Older WH40 still ticking
Less space for wiring
Some older models use same parts.
New T104M mechanism still snaps into enclosure

Intermatic replacement parts
Tork IAP adapter Tork IAP adapter
Any timer can fit into Intermatic enclosure
Just buy another Intermatic timer, and snap new timer into old enclosure.

IAP adapter
Tork timer

Intermatic enclosures
Tork timers and manuals

Solid copper wire only
Insdulation under screw plate
Larger image
Both wires MUST be same gauge
Straighten each wire
Tighten screw very tight against copper wire

Larger image

Connect stranded and solid with wire connector and run jumper to screw plate.
See example image

Use wire connector    
Push on wire connectors
Use push-on wire connectors
3 wires/ or different gauge wires
Join wires with wire connector or push-on connector
Run jumper to screw terminal.
Push on wire connectors
Red 3P connector (shown) for 10-14 gauge wire
How to select and install wire connector
10-3-wire  12 Ga
10 gauge or 12 gauge?
10 gauge is larger/ for 30 amp breaker. 12 gauge is smaller/ for 20 amp breaker
10 gauge wire can have black-white or black-red
12 gauge will have black and white wires

Buy short pieces 10 and 12 gauge wire at local box store
Compare with your wire.
Match color code and amp rating for wire
With 120 and 277 Volt circuits, white wire is always Neutral, and black is Hot
Hot wire is always switched on-off. Neutral wire remains connected without switching.
With 208 and 240 circuits, both wires are Hot, and both wires carry voltage.
Either Hot wire can be switched on-off. Or both Hot wires can be switched on-off.
Add black tape when white wire carries voltage (applies to 208 and 240V circuits)
CA3750 has 5 knock-outs
1 on back, 1 on each side and 2 on bottom

Keep enclosure door closed
Fire safety
Always keep enclosure (box) cover closed
Romex connector Use Wire connectors, or conduit clamps to secure wire to enclosure
By code, all wire must be securely attached to enclosure to prevent wire pull-out.
Wires or conduit must be secured to structure, so there are no loose wires.
Wires inside the enclosure cannot lay over top of connection terminals.
Join all ground wires together and cover with wire connector.
Push ground wires down and away from connection terminals.
2T2500GA plastic outdoor enclosure has 5 knock outs for 1/2" and 3/4" Wire connectors 1 on back, 1 on each side and 2 on bottom
More Intermatic enclosures
30 amp breaker use 10 gauge /

10-2 gauge/ 30 amp
10-3/ 30 amp
Southwire electric tools
Yellow 12 gauge 20 amp

Yellow/ #12 gauge wire for 20 amp
with ground
12-2 gauge/ 20 amp
12-3/ 20 amp

NMB is house wiring
UF is underground
Rolls of stranded wire
White 14 gauge 15 amp

White/ #14 gauge wire for 15 amp
with ground
14-2 gauge/ 15 amp
14-3/ 15 amp

NMB is house wiring
UF is underground
armored cable
Armored cable
Southwire armored cable cutter
Southwire armored cable cutter
Rolls of stranded wire

Stranded wire
stranded wire
Rolls of stranded wire
50-60 amp breaker use 6 gauge /
6-2 wire
6-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
40-50 amp breaker use 8 gauge /
6-2 wire
8-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
Copper ground wire
Use same size as other wire in circuit

12 gauge copper ground wire
Ground wire
Green ground wire
Ground pigtails
Ground rods/ ground clamps at Amazon

End cutting nippers at Amazon

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