How To Install an Intermatic T104 Timer


  4 out of 5 stars on 31 ratings
(Click on a star to add your rating)

Running pool equipment 24 hours is usually unnecessary and expensive. Installing an Intermatic T104 timer is a great way to dramatically reduce run time and energy costs. The following steps will provide a guide on how to install the T104 timer. Note, timers vary with supply voltage. A T104 timer is used for 230V supply voltage. If you are using 115V supply voltage, you will need a T101 timer. The installation steps are the same for either.

Click Here to Find Your New Intermatic T104 Pool Timer 

Step by Step


Step 1

Open up the T104 box and remove the black plastic insulator. The insulator is held in place by one screw.

Click Here to Find Your New Intermatic T104 Pool Timer 

Step 2

Locate an area on the wall near the pool equipment for the timer box. Locate the timer out of reach of the sprinklers or drainage spouts.

Step 3

Mark the locations for the three mounting screws. One is located on top of the timer box and two are located inside the timer box towards the bottom.

Step 4

Drill three holes where the mounting screws will be installed. Note: We used a special 3/16" carbide drill bit to drill into the concrete.

Step 5

Install screws (or other hardware appropriate for the mounting surface) through the mounting holes of the Intermatic T104 timer box. Note: We used 1/4" x 1-1/4" hex head concrete anchors. Hex head anchors are recommended for better traction when installing into concrete.

Step 6

Remove two of the knockouts from the timer box. One knockout will lead to the breaker panel and the other will lead to the pool equipment.

Click Here to Find Your New Intermatic T104 Pool Timer 

Step 7

Thread a 1/2" mpt terminal adapter into the knockouts on the timer box.

Step 8

Your next step is to wire the power from the breaker panel to the pool timer. When wiring, be sure to follow local and NEC/CEC electrical codes. CONTACT A PROFESSIONAL ELECTRICTIAN IF YOU ARE UNCOMFORTABLE WORKING WITH POWER. Incorrect wiring can cause dangerous shocks and may void your warranty.

Step 9


Step 10

Measure the distance from the breaker panel to the timer box. Cut a piece of 1/2" electrical conduit to match this distance.

Step 11

Feed the three cables from the breaker panel through the conduit and into the Intermatic timer box.

Click Here to Find Your New Intermatic T104 Pool Timer 

Step 12

Press the conduit into the terminal adapter.

Step 13

Connect the ground wire to the green screw located on the Intermatic timer mechanism. The ground wire will be green or exposed copper.

Step 14

Locate the two input power cables that come from the breaker. Connect one to terminal 1 and the other to terminal 3. Terminals 1 and 3 are called the "Lines". Note: it does not matter what color goes to 1 or 3. It only matters that one cable is on 1 and the other is on 3.

Step 15

The next steps will involve connecting the equipment to the timer.

Step 16

Measure the distance from the equipment to the timer box. Cut a piece of 1/2" electrical conduit to match this distance.

Click Here to Find Your New Intermatic T104 Pool Timer 

Step 17

Feed the three cables from the equipment through the conduit and into the Intermatic timer box.

Step 18

Press the conduit into the terminal adapter.

Step 19

Connect the ground wire to the green screw located on the Intermatic timer mechanism. The ground wire will be green or exposed copper.

Step 20

Connect the cables running from the equipment to terminals 2 and 4. One cable will go to teminal 2 and the other to terminal 4. Terminals 2 and 4 are called the "Loads". The Loads are what the timer controls. Note: it does not matter what color goes to 2 or 4.

Step 21

Place the black plastic insulator back into the box and tighten the screw to keep it in place.

Click Here to Find Your New Intermatic T104 Pool Timer 

Step 22

The next steps will involve programming the timer.

Step 23

There is a silver Time Pointer on the Clock-Dial. This Time Pointer will point directly to the current time.

Step 24

To set the time, pull the Intermatic Clock-Dial outward. Turn the dial in either direction and align the exact time of day on the Clock-Dial to the Time Pointer. The picture displays the timer set to 12:00 pm.

Step 25

The next steps will demonstrate how to set the trippers. The trippers will determine when the equipment will turn on and off.

Step 26

Locate the "On" tripper. The "On" tripper is typically green and will be labeled "On".

Click Here to Find Your New Intermatic T104 Pool Timer 

Step 27

To set the "On" tripper, hold the tripper against the desired time and tighten the tripper screw firmly. The picture displays the "On" tripper set at 8:00 am.

Step 28

Locate the "Off" tripper. The "Off" tripper is typically gold and will be labeled "Off".

Step 29

To set the "Off" tripper, hold the tripper against the desired time and tighten the tripper screw firmly. The picture displays the "Off" tripper set at 4:00 pm.

Step 30

Turn on the the power at the breaker panel.

Step 31

The Intermatic T104 Series Timer should now be successfully installed. The yellow clock dial should be spinning and the equipment should turn on and off at the set time. Close the timer door and enjoy the energy savings with using a timer.

Click Here to Find Your New Intermatic T104 Pool Timer 


(1 to 40 of 99)

 Posted: 3/10/2020 

What is a good digital replacement for T104P time switch? I would like to have remote access to the digital time switch to enable on/off operation. Thank you for your recommendations.

InyoPools Product Specialist  Posted: 3/11/2020 

Hello, The digital replacement mechanism for the T104 is part number P1353ME

 Posted: 2/14/2020 

How do you install a second set of trippers to have it turn on and off again later in the day?

InyoPools Product Specialist  Posted: 2/17/2020 

Another set of trippers can be added to the clock face: Two Intermatic Trippers 1 Off & 1 On - 156T1978A

 Posted: 12/21/2019 

My instamatic timer has worked flawlessly for years now it turns on okay but turns off before it's supposed to

InyoPools Product Specialist  Posted: 1/3/2020 

Is the "off" tripper still in the original position? It's possible it was inadvertently moved, causing it to kick off at the incorrect time.

 Posted: 7/25/2019 

On my box the wire pop outs are solid and there's no way to get them out, it almost looks like I'll literally have to drill them out with a small hole that normal? Shouldn't they be just pry out?

InyoPools Product Specialist  Posted: 8/7/2019 

The pop-outs should be relatively easy to remove, as they should just "pop out."

 Posted: 2/7/2019 

My T104 is not turning on the equipment with the green pointer. The yellow wheel do not spin? The black gear through the large hole is spinning. The timer is advancing and will shut off the equipment with the copper turn off pointer. The manual lever is not going to the right to turn on my pool pump/ salt system. please assist. I have done all the steps as described in this guide. thanks john

InyoPools Product Specialist  Posted: 2/8/2019 

Hello John - You may have a defective mechanism. The replacement is part number T104M.

 Posted: 2/8/2019 

i replaced the green arrow and torqed it down nice n tite. had extras. works real good now. The yellow wheel was indeed spinning nice and slow. Thanks all is good now. I have t104 in metal and plastic. `Peace.

 Posted: 6/25/2018 

Thanks for these directions. They're excellent - clear, concise. I used them this afternoon, and we're back in business.

 Posted: 4/9/2018 

Hello Jim - We would suggest returning the T104 and getting the 110v T101 mechanism.

 Posted: 4/6/2018 

My GE 15307 timer clock quit working. The GE is discontinued so I bought an Intermatic 104 to replace. When I took the GE out I found I only had 110V going to the timer. When I put the Intermatic in it would not work. I put the old GE back in and the pump did work again but the timer clock did not

 Posted: 2/9/2018 

carol - The T104 runs on 220V. Make sure your supply voltage to the timer is 220V. Check that the input voltage lines are connected to terminals 1 and 3 as shown in Step #14. Check that the white timer motor lines are also connected to terminals 1 and 3. Lastly, check that the yellow clock disc is engaged. Pull it out and release it a couple of time to make sure it engages with the timer motor gears.

 Posted: 2/3/2018 

Just replaced a non functioning old Intermatic timer with same model T104. Checked that all is wired according to direction here. Turned back on and pool motor working fine but clock is NOT advancing. . . .!!

 Posted: 11/26/2017 

RP - Unfortunately, Intermatic timers are designed to control 220V or 115V. As far as I know, there is no way to rewire them to control both levels of voltage.

 Posted: 11/26/2017 

I have a 220v intermatic timer controlling my pump. How can I hook up a 110v item or plug to it? Can I just use one of the 110v legs coming into the box, but where would my neutral wire go? Obviously the ground wire goes to the ground.

InyoPools Product Specialist  Posted: 9/28/2017 

hello - Not that I am aware of. This is a 220V timer. Both of your supply wires are 110V and there is no neutral wire. The timer/clock is only set up to control 220V.

 Posted: 9/26/2017 

I have 220 wired into the box. I'm running out teo outlets with 220. Is it possible to wire an additional outlet for 110? Thank you

InyoPools Product Specialist  Posted: 8/30/2017 

Anonymous (T104 trippers) - No, it does not matter where the manual switch is set. When the yellow dial rotates, the ON tripper will contact the switch at the time you set and flip it to ON (or leave it at ON). When the dial rotates to your OFF position, the OFF tripper will flip the switch to OFF. Make sure you have both trippers installed and that one is an ON tripper and the other is an OFF tripper. One is longer than the other.

Anonymous  Posted: 8/29/2017 

You have a t104 are does it matter what the manual switch is set to will it still turn on and off if the timer is set to run at 10 a.m. and shut off at 3 p.m should it be in the off position all the time for the on position all the time would be leaving for several months but we wanted to run everyday and it doesn't seem to be doing that thank you.

InyoPools Product Specialist  Posted: 8/5/2017 

Frustrated - I assume you replaced the whole timer and not just the motor or the timer mechanism. Check that you have the correct timer for your voltage. T104 for 220V. T101 for 115V. Then check that the white motor wires are connected to terminals 1 and 3. Also, check that the two supply wires from the breaker box are attached to terminals 1 and 3 and that the grounding wire from the box is attached to the grounding lug on the timer. Turn the manual timer switch off. Take the "ON" and "OFF" trippers off the dial so they aren't a factor. The motor should run and the yellow dial should advance in time.

 Posted: 8/2/2017 

My pool timer was 17 years old. I just had my pool resurfaced and shortly afterwards the timer quit working. If you looked into the peep hole you could see the gears turning but the clock dial didn't move (it was engaged, checked that). I purchased a new timer, installed it and the gears didn't even turn. Returned that one installed another new one. This one I could see the gears turning so I walked away to give the clock dial time to move. I came back later to find the breaker tripped at the box and also tripped the breaker at the main panel in the house. I reset the breakers and now the gears are no longer turning. What now?

InyoPools Product Specialist  Posted: 7/7/2017 

Anonymous (timer ground) - If your timer doesn't have a ground wire coming into it from the breaker box, you should rewire that circuit to include a ground wire.

Anonymous  Posted: 7/4/2017 

Trying to replace a timer, but there was no ground wire on the one being replaced. What's a solution?

InyoPools Product Specialist  Posted: 7/4/2017 

Stephen - Thank you for your feedback. You are correct. 12 gauge wire could not be used on a heater's 60 amp circuit. It would be more like 6 gauge. However, this timer installation is intended for a pump, not a heater. I do not see where we say that a 12 gauge wire is required to connect the timer to a heater. We could probably be clearer on how this timer is going to be used.

 Posted: 6/30/2017 

It shows that 12 gauge wire is used to connect the timer to the heater. How can that be when at 60 amps that wire would not suffice? I'm confused. I have a 125 BTU Hayward heat pump and was told to use an Intermatic Timer 220 Volt Plastic Enclosure - T104P3. Does anyone have the same combo? If so, how did you wire it?


 Posted: 5/30/2017 

i have 2 20amp circuits that are wired to box and one wire from panel shows 0 volts when grounded (neutral), the other 2 show 110.

want it to control a new pump (set at 115) via timer and manual override.

a GFI outlet a on/off switch to swimming pool light

and (auto( temperature controlled /on/off switch that controls solar heating to pool.

the intermatic switch is a T104M model.

the A post is connected to the neutral, the other two wires to the line (which is 1 and 3 which have the associated clock wires), the pump is connected to the 2 and 4 post.

clock runs correctly but the electric motor / pump does not work when manual switch is ON. haven't bothered to test to see if timer will start pump.

without the pump wires connected, a voltage tester shows 0 when manual switch is off and 110 when on.

with the wires connected a voltage tester shows 0 when manual switch is off and goes off the chart when manual is set on.

1st, am I using the correct switch? if not, which one?

any ideas on how to fix or test?


InyoPools Product Specialist  Posted: 5/15/2017 

chipper - Make sure the white wires from the clock motor are attached to terminals 1 and 3 and not 2 and 4. If they are wired correctly, I'd replace the clock mechanism. See our guide on "How to Replace an Intermatic T104 Mechanism".

 Posted: 5/12/2017 

on trip is tight. the dial stops turning as soon as the timer shuts the pool down

InyoPools Product Specialist  Posted: 5/11/2017 

chipper - The "ON" and "OFF" trippers are different. See step 28. Make sure you have placed an "ON" tripper where you want the pump to be turned on. Also, make sure the tripper is on tight so it flips the switch on. If this doesn't correct the problem, you may need to replace the timer mechanism.

 Posted: 5/10/2017 

timer will turn off pool, but not start it. where should the manual switch be set

InyoPools Product Specialist  Posted: 2/17/2017 

wire gauge - The selection of wire gauge between the timer and pump depends on three factors: HP, supply voltage, and distance. An 115V pump will use twice the amperage as a 230V pump. If the distance to your pump is less than 50 feet, for a 1HP or less pump, on 230V you would need 14 gauge wire - for 115V you would need 12 gauge wire. If the distance to the pump is between 50 feet and 100 feet and you have a 1 HP pump, 230V requires 12 gauge, 115V requires 8 gauge. For a 3/4 HP pump, 230V requires 12 gauge, 115V requires 10 gauge.

Anonymous  Posted: 2/16/2017 

What gauge/type wire should be used from timer to pool pump?

InyoPools Product Specialist  Posted: 12/12/2016 

Timer wiring - Are these two additional wires than what is shown in this guide and where are they. I would have to know more about the make and model of this timer to help you.

Anonymous  Posted: 12/11/2016 

The new timer has two black wires that the old timer doesn't have. Where do they go?

InyoPools Product Specialist  Posted: 11/22/2016 

Tino - I'm assuming you are trying to install a timer for a 220V system since you have two hot wires coming into the timer. And I'm not sure which timer mechanism you have but the T101M mechanism has the same 5 number of terminals as the T104M mechanism. A major difference between the T101 and T104 timers that you have to consider is the timer motor. The T104 runs on 220V; the T101 runs on 110V.

 Posted: 11/21/2016 

I have the 101 series and I have two hot lines coming in and the timer only has tree terminals instead of five is there a way to ether buy extra terminals or there is deferent wiring options.

InyoPools Product Specialist  Posted: 8/26/2016 

mrjaydeeone - You should have a label inside the cover of the timer box that identifies your timer as a T101 for 110V, or a T104 for 220V. If that label is gone, take the timer mechanism out and look at the back of the timer motor. It will be labeled 110V or 220V specifying what voltage it uses. If your clock is not moving, it is likely that the motor has failed and you would only have to replace the motor. See our guide on "How To Replace an Intermatic T104 Clock Motor". Or if the whole mechanism has failed due to jammed gears, see our guide on "How to Replace an Intermatic T104 Mechanism".