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.