Shelf Above Electric Fire . The fireplace unit is 21 inches high so it will stop at 63 inches (33 inches will remain). Artemis modern white electric fireplace mantel & insert with sound and heater. shelf for above fire place Wall mounted electric fires, Electric from www.pinterest.com Essentially, if your shelf protrudes fewer than 1 1/2 inches outward from your wall, then the spot that you place the shelf must leave a height of at least 6 inches between the shelf and the topmost part of the fireplace. A fireplace mantel, also known as a mantelpiece , commonly refers to the flat area located at the top of a fireplace. This flat area of a mantel provides an opportunity to place household items on top of the fireplace to help it become more of a feature point for a home.