Question about Intermatic T104M 208-277Volt 40-amp Timer Switch-Double Pole / Single Throw

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Installing of a t104 208-277 v

How to install this to a 30 30 amp breaker which is in the basement time is going to control 3 to 4 signs already powered by the breaker its self i just want to eliminate turning them off and on manually

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  • Joel Wiedeman May 11, 2010

    clock motor 208-277V rating?



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Posted on Jan 02, 2017


SOURCE: On 10/12/10 electrician installed an Intermatic

I believe your timer must be exposed to cold.
The CR2 battery in ST01C will only last 30 days when exposed to cold temperatures.
I was reading a pdf chart few months ago about timer batteries, and the power drop-off becomes really steep after 30 days.

Most digital programmable timers are susceptible to cold if they have battery or internal rechargeable battery that supports timer functions or acts as program back-up.
For example, I e-mailed Honeywell about their Aube rechargeable-battery-type-timer, and they said anything below 32F and the display becomes slow, and timer loses accuracy.

Your ST01C wiring is correct. I test timers. They don't operate if wiring is wrong.

I solved same problem with my back porch timer using GE 15070 mechanical dial timer. Home Depot sells in-store for $18.
Link below gives you photo, manual, and wiring instruction so you don't need electrician.
Open page and notice the timer below the 15070 has a photo insert showing on-off pins located on timer dial.
You move pins with ink pen or fingernail file.
Of course this is not self-adjusting digital timer, so I just set it for times I want, and it's easy to change times. It will be perfect for 6pm to 11pm daily.

And then use ST01C on a indoor switch.
You can wire the ST01C yourself by simply looking how each wire is connected now, or you can add a comment to this thread later and I will answer:

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, fixya expert speaks with you over phone while you work on timer.

Posted on Jan 11, 2011


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Copy following link:

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Both sides might be controlled by same 60 amp breaker, or the heater might be controlled by two separate 30 amp breakers.
Be sure you have correct wire and breaker.

After reading steps on link above, add comment and say if this is new installation, or older installation that suddenly started throwing breaker.

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I have a new furnace and the breaker keeps tripping (20/30). It is a bryant westinghouse box. I think 200 amphes

1) You got a FIRE truck coming.

2) Wire is too small.
Problem is NOT circuit breaker.

3) Both 240Volt appliances on same breaker is a hazard, especially if space available in 200 amp service panel for more breakers.

4) Usually each 240V appliance has separate breaker.

5) Circuit breaker trips because of High heat on the wire.
If wire gets hot, it will start a fire inside the wall.

Electric code requires wire-size match breaker-size.

6) If you put larger amp breaker on same wire that is getting hot, then wire will get hotter.
Result: FIRE truck middle of night with folks jumping out window in glass-cut bare run across yard.

7) Each appliance has volts and watt rating on label.
EVERY appliance has label.

8) For example stove might be rated 8000 watts and 240Volt.
8000 watts divided by 240 volts = 33.3 amps
Stove would require 40 amp breaker and 8 gauge wire.

9) How to figure it out:

10) Do same calculation for new furnace.
12000 watt furnace divided by 240 volts = 50 amps.
Use 60 amp breaker and 6 gauge wire.

11) Summary: fixya wants you to be safe, and buy stuff showing in the ads.
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T103 has 120Volt clock motor, so we can wire this timer.

T103 timer is rated for 30 amps and 2horsepower and your blowers use 28 amps.
So we're getting close to max on the timer. Hopefully blowers won't all be started at one time since motors draw maximum amperage when they start.
However, you need 30 amp breaker and orange 10 gauge wire for that much amperage >> unless only one blower is turned ON at any given time.
Always match wire size, amperage of breaker and amperage of Load or it will trip the breaker.
If you put 30 amp breaker on size 10 wire it is good. But 30 amp breaker on smaller size 14 or 12 gauge wire is fire hazard.
Add a comment at any time, and I will respond

Look at the basics:
You have 2 cables.
One cable comes from breaker box.
Other cable goes to three 120V plugs (120V is same as 110V).

Each cable has black-wire, white-wire and bare-copper-ground-wire.

How to wire the timer.
Timer has 5 terminals: A 1 2 3 4

A) Cable from breaker box:
White wire from breaker connects to terminal A
Black-wire from breaker connects to terminal 1

B) Cable going to 3 plugs
Black wire to plugs connects to terminal 2
White wire to plugs connects to terminal A
Ground wires connect to green ground screw.

Terminals 3 and 4 are not used in this case.
Here is a wiring diagram that shows 120Volt from breaker box and 120Volt going to Load

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