This was very easy to install. Since this is for an outdoor application, I used liquid flexible conduit, water proof connectors/interfaces and outdoor wire. I used water-proof connectors throughout and redid the connection to the pool pump as that was shorting out whenever it rained heavily and wouldn't stop shorting to ground for a week or two. This started after the heavy rains during the remnants of a tropical storm in the fall of 2011 that caused flooding throughout our area and left a film of dirt on the bottom of our pool. This replaced a mechanical timer that no longer worked properly. I will rework it and use it for other applications if I can make it work again. The product was very easy to wire up. I am using it in 110 V mode. The power comes in and you connect the common and the hot wires to the appropriate terminals. Do the same out to the load using the load out terminals which for me is the pool pump. You then wire in a 3 way switch into the switch terminals. I just wired all the grounds together in the box. It would have been nice if they provided a ground terminal for all the connections but this is unnecessary. The common and hot wires establish the 110 V levels or 220 V levels if you were to run that type of load.There are cutouts for all the connectors where the wires come in. I just used a pocket knife to remove the appropriate sized cutout. I would have thought that the cutouts could have been made easier to remove but making sure it maintains waterproof properties is very important so I would prefer that they err on the side of maintaining waterproof properties. I am very happy with the programmability. Seven days and one on and one off event per day which is enough for my application. With the external switch all the functionality I need was there. The override can also can be done internally at the display but the external switch makes it super easy. I can't complain, you can pay alot more for similar functionality in a digital timer switch box. So this did exactly what I wanted it to do and I am very happy. So long as it lasts a long time I will continue to be happy. If I can edit this review later, I will let you know how it lasts over time. But so far, no complaints.