Install a triple chip carbide blade in your table saw according to the manufacturer's directions.
Make sure the blade is at a 90 degree angle. Use a ruler to measure the distance from the blade to the fence of the table saw at the front, middle and back of the blade. The distance needs to be the same along the length of the board for a straight cut. Refer to you table saw manufacturer's directions on how to adjust the saw blade.
Set the blade height to 3/4 of the thickness of your melamine shelving. For example if the shelving is 1 inch thick, set your blade height to three-quarters of an inch.
Measure the opening where you want the shelves to be placed. Mark the measurement on the melamine shelving using a ruler.
Adjust the fence on your table saw to the measurement you want your shelves to be cut.
Put on eye protection.
Hold one edge of the shelving against the table saw fence. Turn on the table saw. Place your hands on either side of the mark you made on the shelving. Leave plenty of room between the blade and your hands to ensure your safety.
Push the shelving through the blade using even, consistent pressure.
Turn the shelving over and cut the shelf from the other side, following the same safety precautions.