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Replace T104 with EH40

Intermatic 156T1978A tripper T104 mechanical timers can be noisy
-To quiet a noisy timer, you can sometimes install rubber washers behind the timer or install new clock motor.
-Also disassemble and clean parts, adding a bit of white grease to metal gears
-Change clock motor

T104 clock motor
T104 trippers
White grease

Pictures of disassembly of timer
Noisy timer

Clock motor has plastic gears
WG1573 clock motor
Look for clock number
T104 can usually be repaired
-The motor and trippers can be replaced
- T104 is designed to be repairable. For example. the trippers are made of softer metal than the unrepairable on-off switch they push during each rotation around the dial. Inspect the impact point for wear ... add white grease.
If the impact point where trippers meet the switch is worn down, then timer is no good. Otherwise replace trippers.
Another example is the clock motor is replaceable and has plastic gears. The reset of the timer has steel gears. The plastic gers wear out before the steel gears. Clean the steel gears, add a bit of white grease, and replace clock motor.
The enclosure (box) is standard for all Intermatic T100, EH, ET series timers. So you can snap
-Other parts can wear out. For example using stranded wire, or loose wires can cause burned terminals that are not repairable.
T104 mechanism to snap into existing enclosure
Pictures of dissambly and repairs
T104 repair parts
Intermatic enclosures
Check your voltage
T104 and EH40 are both rated 240 volts.
-Do not connect wrong voltage to EH40
T101 and T103 timers are 120 volt, replace with EH10

-The T104 is 240 volt ... you can check three different ways.
1) is the 240 volt clock motor WG1573, the 120 volt clock motor is WG1530
2) is the breaker a double? if yes then voltage is 240 volt.
3) Use multimeter and check for 240 volt across terminals 1 & 3
 .... the basic standard is that voltage must be within 80% of rated value, or minimum 192 volts. Below 80% threshold, electrical designs do not function as expected. Overvoltage, or surge, cause equal problems for electrical systems. T104 is repairable after typical surge event, EH40 is not repairable,
Electrical resources on the site
Intermatic T104
-Crossover wiring
T104 has 5 terminals A 1 2 3 4 (terminal A is not used)
EH40 has 6 terminals 1 2 3 4 5 6

/Line from Breaker
T104 terminal 1 goes to EH40 terminal 1 & 3
T104 terminal 3 goes to EH40 terminal 2 & 5

T104 terminal 2 goes to EH40 terminal 4
T104 terminal 2 goes to EH40 terminal 6

-EH40 will snap into the old T104 enclosure to save work

-The T104 is a valuable asset to sell on ebay or keep in backup.
Enclosure (box) and timer mechanism can be sold separately.

How to wire EH40
How to wire T104

Orange 10 gauge 30 amp breaker

Orange/ #10 gauge for for 30 amp circuits including water heater
with ground
10-2 gauge/ 30 amp
10-3/ 30 amp

NMB is house wiring
UF is underground

Yellow 12 gauge 20 amp breaker

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

Rolls of stranded wire

NMB is house wiring
UF is underground
White 14 gauge 15 amp breaker

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

Copper ground wire
Use same size as other wire in circuit

Spools of ground wire

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