VERY IMPORTANT: Understand that in US residential wiring the WHITE wire is _NOT_ ALWAYS_ the neutral wire. Additionally, prior to 1999 the National Electric Code (NEC) did not require that these white wires be re-identified with black tape or similar means when used for purposes other than neutral. The white wire is sometimes used as a hot, especially when wiring Intermatic T103 and T104 timers.
Also understand that the WHITE neutral wire and the bare (or green) equipment grounding wire are connected together ONLY at the main electric power panel and must _never_be connected
together _again_. Once those two wires leave the main electric panel, the WHITE neutral wire must _always_ remain insulated from the bare or green equipment grounding wire. This is very important for safety
considerations.
If your wiring is very old and does not have a bare equipment grounding conductor, you _must_ protect the circuit with a GFCI (Ground Fault Circuit Interupter). GFCI wiring is not difficult but is beyond the scope of this post.
DETERMINE WHAT CABLE YOU HAVE:
Usually one will find one of the three following scenarios for the incoming supply cables when wiring a T103 or T104
Intermatic timer:
1...A 120 volt cable with 3 wires: black, white, and bare. The black is LINE (hot), white is neutral and bare is equipment grounding. Black to white is 120 volts. This scenario can be used with the T103, but not the T104.
2...A 240 volt cable with 3 wires: black, white, and bare. The black is LINE(hot), the WHITE is LINE (HOT), and the bare is equipment grounding. Black to white is 240 volts. This scenario is used with the T104 ONLY.
3...A 120/240 volt cable with 4 wires: Black, red, white, and bare. The black and red are (LINE) hot, white is neutral and bare is equipment grounding. Black to red is 240 volts. Black to white is 120 volts. Red to white is 120 volts. This scenario can be used with either the T103 or the T104.
The only difference between the T103 and the T104 is the timer motor voltage rating. The T103 uses a 120 volt timer motor and the T104 uses a 240 volt timer motor. The T103 timer motor is connected to terminal "A" and terminal #3 during manufacturing. The T104 timer motor is connected to terminal #1 and terminal 3# at the factory.
Also, when connecting the bare or green wires to the "GR" terminal, it is best to wirenut the wires together with a pigtail, then connect the pigtail to the "GR" (GRound) terminal, WHICH IS THE GREEN SCREW ON THE LOWER PART OF THE CASE.
WIRING THE TIMER:
The wiring diagram for the T103 is here:
http://www.progressive-growth.com/wiring/T103.pdf___________________________________________________________________
WIRING THE T103 USING AN INCOMING 120/240 VOLT CABLE WITH 4 WIRES (scenario #3):
Incoming (LINE) wires from 240 volt circuit breaker:
Connect the black (LINE)(hot) wire to terminal #1. Connect the red (LINE) (hot) wire to terminal #3. Connect the white (neutral in this case) wire to terminal "A".
Connect the bare equipment grounding wire to the "GR" terminal, which is the green screw on the case.
Outgoing wires to 240 volt load:
Connect one (hot) wire to terminal #2 and the other (hot) wire to terminal #4. The bare or green wire goes to the "GR" terminal.
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WIRING THE T103 USING AN INCOMING _120_ VOLT CABLE WITH 3 WIRES (scenario #1):
Incoming wires from 120 volt breaker or source:
Black (LINE) to terminal #3. White (neutral) to terminal "A". Bare to the "GR" terminal.
Terminals #1 and #2 are NOT used in this case.
Outgoing wires to 120 volt load(s):
Black(hot) to terminal #4. White(neutral) to terminal "A". Bare to the "GR" terminal.
The wiring diagram for the T104 is here:
http://www.progressive-growth.com/wiring/T104.pdf______________________________________________________________
WIRING THE T104 USING AN INCOMING 240 VOLT CABLE WITH 3 WIRES (scenario #2):
Incoming (LINE) wires from breaker:
Connect the black (LINE) (hot) wire to terminal #1. Connect the white (LINE) (hot in this case) to terminal #3. Connect the bare wire to
the "GR" terminal.
The "A" terminal is _NOT_ used.
Outgoing wires to load:
Connect one (hot) wire to terminal #2 and the other (hot) wire to terminal #4. Connect the bare or green wire to terminal "GR".
The "A" terminal is _NOT_ used.
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WIRING THE T104 USING AN INCOMING 240 VOLT CABLE WITH 4 WIRES:
Same as above, except the white wire is not used. Just tape or wirenut it off.
Comment by gotgeek2, posted on Jan 08, 2010ckuzkuz, I'm a licensed master electrician in 2 states with 30 years in the trade. I've installed a lot of Intermatic timers over the years. I wrote this tip because I saw that a lot of folks were having problems wiring them.
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