I'm going to post my question again and try to be more clear this time.
I have an indoor switch running to.an outdoor receptacle that is not a GFI. Right now, there is a conduit off the receptacle that goes underground and comes up under a cement fountain in a very small enclosed area. In there is a GFI receptacle. Two things are plugged into the receptacle, the first is the pump that runs the fountain, and second is the light package that lights the fountain. Currently, when I turn on the switch in the house, BOTH the lights and the pump come on. That's a bummer and a waste of energy for the daytime, and because of the hassle factor of getting into the space, a timer is not a practical solution. (I've tried it).
I want to install a photo cell where the FIRST (non GFI) is. I cannot install it at the receptacle under the fountain because there is no place to attach it outside, and, by definition, it's ALWAYS dark under the fountain and the lights would be on constantly, which is my problem now.
Here's the current wiring from the first (non GFI) receptacle: There is a four wire (red, black, white, and green) bundle that is pulled though the underground conduit to the second receptacle. The white and red are attached as well as the green ground wire. The black wire in the conduit was unused. Also: IN THE NON GFI RECEPTACLE, THERE IS A BLACK WIRE THAT COME FROM SOMEWHERE INSIDE THE HOUSE THAT IS ALWAYS HOT.IT IS CAPPED. Can this come into play for attaching the photo cell at this location?
I want to continue to have the indoor switch control both the lights and the fountain at the same time, but I want to install this photo cell at the non GFI receptacle that will keep the lights from coming on until dark. Can I do it with the 4 wires in the conduit? If so, how? Also, do i need to make the non GFI receptacle a GFI? If I do, can I then safely make the receptacle under the fountain, a non GFI?