How To Install an Intermatic T104 Timer


  3.96 out of 5 stars on 28 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.

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.

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.

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.

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.

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.

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".

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.


(41 to 80 of 93)

 Posted: 7/1/2016 

question What should the A post be connected to ? In the wiring diagram is says neutral .. when I connect it to the white neutral bar in the fuse box it trips the gfi same if I connect it to the ground bar ... this is a double pole switch with GFI.
When not connected to anything the timer is not working??


InyoPools Product Specialist  Posted: 3/26/2016 

DavidJ - The easiest way to "disable" the timer is to pull off the "ON" and "OFF" trippers. See Steps 26-29 of this guide for instructions on putting the trippers on (or taking them off). The motor on the timer will still run, but it won't engage the on/off switch.

 Posted: 3/24/2016 

Just bought a house that has a T104 on the hot water heater. How do I disable the timer so that the heater functions normally as it would without the timer?

InyoPools Product Specialist  Posted: 3/19/2016 

Dave - Sound good to me. Check the wiring again. On a T104, the inputs are on terminals 1 & 3 and the outputs on 2 & 4. Make sure that the circuit breaker to your timer is large enough to handle both functions.

 Posted: 3/18/2016 

Hi guys, I recently bought a Pentair vs super flo pump w/timer from you and am ready to install. I have an Intermatic T104 timer that is also used to control on roof solar heating. Since the new pump has it's own digital timer can/should I wire this to the 'line' terminals (1&2) so that it has continuous power? I plan on keeping the solar on 'load' terminals (3&4) to control with T104 timer.

As usual, thanks for all the help!


InyoPools Product Specialist  Posted: 3/14/2016 

Doug S - There is a set of contacts on the backside of your timer that may not be closing properly. Look at our guide on "How to Replace an Intermatic T104 Mechanism" to see how to remove this mechanism and see the contacts. You do not have to remove the wires to see behind the mechanism. Make sure the power is OFF. When you manually switch the timer on, you should see both of these contacts close. If they do not, I would replace the mechanism. If they close properly, recheck your wiring.

 Posted: 3/12/2016 

I have it wired correctly but I can not manually shut the pump off with the on/off switch nor does it cut off when it reached the clock trippers. Any suggestions

InyoPools Product Specialist  Posted: 3/7/2016 

George - The knockout plates are cut out most of the way around and are only held in by thin uncut tabs. Force a small screwdriver into the cut out area and pry the plate out. The uncut tabs will break off.

 Posted: 3/5/2016 

How do I open the knockout holes on the timer? A procedure please!



InyoPools Product Specialist  Posted: 2/29/2016 

Captain - I have a call in to confirm these answers with the Intermatic rep but here is my understanding now:
1- According to the fine print in the wiring figure, the "A" connector is used with 277/480 volts not generally available to a typical resident.
2- If you have 220V coming in on the black and red wires and the green is ground, the forth supply white wire is extra and should be capped off.
3- This timer is limited to a total of 40 amps so would not handle a 20 amp pump and a 50 amp heater. I think most users rely on the "no flow" switch within the heater to shut off the heater when the pump is turned off.


 Posted: 2/26/2016 

1.) What is the "A" connection for on the T-104R?

2.) Besides Line #1 (Black), Line #2 (red) and ground (copper), I do have a nuetral (white)wire that is not connected to anything in the timer box. Do I connect it to anything? or do I just cap it off?

3.) Can I wire this timer (T-104R) to start both my pump and heater at the same time? Both are 220VAC, The pump is on a 20amp breaker and the heater is on a 50amp breaker.


 Posted: 2/10/2016 

Read your directions to install a new T104R Timer. I'm a guy who hates dealing with anything electrical and any more than three wires baffles me. You made it easy and SAFE... Thanks a lot, David

InyoPools Product Specialist  Posted: 10/9/2015 

dj- Unfortunately, we do not have that information. I suggest calling Intermatic direct and seeing if they can provide a wiring diagram. Their number is 815-675-2321.

 Posted: 10/8/2015 

i need to control a 1hp. 3phase, 460volt, with a timer i know one can do it with a 230v intermatic timer, Can you supply the wiring diagram for the 1hp submersible water pump motor?

InyoPools Product Specialist  Posted: 9/13/2015 

Pete - I assume your clock motor is good since it sounds like it was advancing the dial when the power to the pump was on. Check that the white motor wires are attached to terminals 1 & 3, the supply voltage, as shown in Step 20. Then make sure the dial is engaged into the clock gears by rotating it left and right slightly.

 Posted: 9/13/2015 

I have completed the wiring as instructed. If I manually flip the on switch the timer will complete the cycle and shut the pump off. Once the unit is off the timer does not continue to move, it stays at the time the unit shut down. What am I missing??

InyoPools Product Specialist  Posted: 8/9/2015 

timer hookup - You have to make sure that your salt system shuts off when your pump is off. So somehow in your wiring configuration you have to tie them to the same timer. If your pump bypasses the external timer, there is a chance that the pump could be shut off while the salt system is left on.

Anonymous  Posted: 8/8/2015 

I have the intermatic timer that was controlling a single speed pump and salt system. I have replaced the single speed pump with a variable speed with its own control panel. I still want to use the timer for the salt system but not the new pump. Should I connect the pump to 1 and 3 just to send power to the pump bypassing the timer?



InyoPools Product Specialist  Posted: 8/6/2015 

Bubba - Not sure what you mean by a double 104 timer. If you want to turn the filter pump and booster pump on at the same time, wire them together to terminals 2 and 4, the output terminals on the timer. See step 20 of this guide. Picture shows one wire going to 2 and to 4. You would have 2 wires on 2 and on 4.

 Posted: 8/4/2015 

I need wire diagram to install a double 104 timer on a filter pump and booster pump.

InyoPools Product Specialist  Posted: 7/10/2015 

WW - Yes the wiring is the same for a T101 as for a T104.

 Posted: 7/9/2015 

Question:Is wiring for T104 the same for T101?

InyoPools Product Specialist  Posted: 7/7/2015 

Ray - The model numbers tell you which voltage you have. If you have a T101P timer, you are set up for 120V. If you had 240V, you would have used a T104P timer.

 Posted: 7/6/2015 

I have an Intermatic T101P Timer currently for my pool that needs replacing. Is there a way for me to see whether my current timer is 120V or 240V without a volt meter? Probably a silly question but I don't often deal with electricity! Thanks!

InyoPools Product Specialist  Posted: 6/30/2015 

Confused - Glad we could help and thank you for the feedback. We seldom get responses and they are much appreciated.

 Posted: 6/29/2015 

INYOPOOLS.COM thanks for your assistance and on your advice and checking voltage with my multimeter, the voltage to my T104 is only 120V. I will contact my electrician to correct this problem.

InyoPools Product Specialist  Posted: 6/28/2015 

Confused - These timers have been around a long time are generally very reliable. Recheck your wiring and ground. Then I would suggest calling Intermatics at 815-675-2321. They should be able to troubleshoot this problem.

 Posted: 6/27/2015 

Sorry, my initial post should have read that my T-101 timer switch operates the pool pump. It still works fine (20 Years). My T-104 operates my pool light. So my pool has two separate switches one for the pump the other for the light. It is the clock motor in my new T-104 that was replaced and the replacement is also not working. Thanks for your assistance

InyoPools Product Specialist  Posted: 6/27/2015 

Confused - You stated that your old timer was a T101 and you replaced it with a T104. Did you change the supply voltage to the T104? T104 runs off of 220V and T101 off of 110V. If this is not the issue, give Intermatics a call at 815-675-2321. They should be able to troubleshoot this problem.

 Posted: 6/25/2015 

I've had my pool for about twenty years now. My Model T101 timer switch that operates the pump still works fine (20 years) my T104 clock stopped about a year ago. Purchase a new complete time switch installed it turned it on but did not operate. Then I manually touched the wheel and the clock started working. Everything worked fined until there was a power break and the clock would not start until it was 'touch' to get it started again. Purchase a new clock motor and installed..and the same thing happens. Is this a problem with the clock model WG1573-5E 208/277V 60HZ??

InyoPools Product Specialist  Posted: 6/4/2015 

Clay - If this is your second timer, I doubt that it is a faulty timer. The only thing I can think of is that the on/off tripper might be installed wrong. Check your installation of the trippers against the pictures in Steps #27 and #29.

 Posted: 6/2/2015 

Installed a new timer and the clock will rotate but it will jam when it gets to the on or off switch. It will run manually so the main and buster pumps work just fine. What could be causing this? I took one back to the store and installed another, so I don't think it is the timer.

InyoPools Product Specialist  Posted: 5/30/2015 

lj- Check to make sure all the input and output connections to the timer are tight. Else you might try replacing the timer mechanism. See our guide on "How to Replace an Intermatic T104 Mechanism" It's the same as replacing a T101 mechanism except T104 is for 230V. Buy the T101 Mechanism.

 Posted: 5/28/2015 

T101 Drops voltage on the load side when timer turned on. 120v on incoming line when off, drops to 106v on the load side. Not able to turn the pump on, consistently cycles

InyoPools Product Specialist  Posted: 5/12/2015 

Timer motor - Yes, the clock dial should turn once every 24 hours to trip the system on and off. Sounds like you have a bad timer motor. See our guide on "How To Replace an Intermatic T104 Clock Motor" for more information. It's a relatively easy repair.

Anonymous  Posted: 5/11/2015 

Just opened our pool and the clock dial is not turning. Should it always turn, even with the manual lever on? Sorry, I'm sure it's a silly question, I'm new to pools:)

InyoPools Product Specialist  Posted: 4/20/2015 

Evaleen - An extra "A" terminal is provided on most 2- speed motors to allow foe switching between high and low speeds on a 2-speed motor. See our guide on "How To Set Up the Intermatic Pool-Spa Control System for 2-Speed Pump" for an example of one application.

 Posted: 4/18/2015 

what is the A terminal used for?


 Posted: 3/25/2015 

Great tutorial! Inyopools is always my 1st stop when I need to know anything about my pool. I just installed a T104 timer according to you like a dream. Thanks again!

InyoPools Product Specialist  Posted: 8/6/2014 

Krista - I don't know why the timer would work fine for two days then stop working. The T104 timer is for 220V. If your supply voltage is 110V, I don't think it would have worked for two days. Give Intermatics a call at 815-675-2321. They may have an answer.