My question is that I have an outlet in the bathroom right next to the sink. (Big NO NO) This outlet has 3 whites to it and 3 blacks to it with the proper grounds. This would place it in the middle of a series. How do I distinguish the line and the loads to replace the outlet with a GFI Outlet?? In theory there should only be 1 line and 2 loads??

Tim

Your theory is correct, only one set of wires will be the feed, or input into the box, the other two sets will be feeding other devices.

Knowing which set is the feed will require the black splice to be broken and the wires separated, and use a voltage tester to find the live one.

This will only be necessary to protect the other devices downstream of the GFI, the other load wires.

If your only going to replace the existing outlet with the GFI, and the GFI will not protect any other devices, all you need to do is splice on short pigtails onto the white and black and connect to the LINE of the GFI.

Be aware of box fill GFI devices take up more room in a box that standard outlets, and with 3- 2 wire cables, each with a ground wire in the box already, there may not be enough room for all these wires plus the larger GFI device.