I am attempting to exchange a regular recepticle with a gfci.Upon opening the box, I saw that there is a tan wire grouped with the white neutrals.I tried several scenerios with trying to pig tail the grouping to the neutral line on the gfci. It tripped. There is a cabinet light above the box and when I disconnected the brown wire it shut off the light. This brought me to the conclusion that the brown wire is a switch loop. Is there any way I can arm the gfci with this hot brown grouped to the whites and previously pigtailed to the neutral on the receptical which worked , but not now with the line neutral on the gfci? Thx, Jal64