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The cover can be removed by loosening the screws securing it to the outlet. There will either be one screw in the center, or two screws on the top and bottom of the outlet cover. Place the outlet cover and the screws aside. There will be two long mounting screws securing the electrical outlet to the blue electrical box. Remove them so you can insert the outlet extenders. Since the tile adds additional depth from the wall, the original outlet location will be sunken back from the tile surface. You can use either accordion-style or box-style outlet spacers to raise the outlet flush with the tile.  The accordion design spacers fold over with 1/8” added for each segment. If the depth of your new tile is 5/8” thick, then you can add five segments to raise the outlet 5/8”.  An outlet box extender is a rectangular ring that fits over and behind the outlet to add additional space between the original outlet box and the outlet. Regardless of which type of extender you use, the design has a hole, so you can feed the mounting screw through the extender and back into the outlet box. You won’t tighten it down until after you place your tile. This will also allow you to test if your current screws are long enough to reattach the outlet with the extender in place. You may have to purchase longer screws.

Summary:
Remove the cover from the electrical outlet. Unscrew the outlet from the electrical box. Insert outlet extenders to a sufficient depth for your tile. Reattach the outlet loosely with the spacers in place.