To install steel fence posts, mark the location of each post, then remove any obstacles to digging a hole in that location, such as rocks or gravel. Also ensure that the ground around the fence post is level. With a fence hole digger, create a hole for each fence post that is approximately 2 feet deep.
Hammer a thin steel stake into the bottom center of the hole to hold the fence post upright and in place. Fill the bottom of the hole approximately two-thirds full of gravel. Place the steel fence post over the stake and force it into the hole until gravel encompasses the bottom of the fence post. Use a level to ensure the post is vertical within the hole, then fill the rest of the post hole with wet concrete.
An alternate method starts with digging a hole three times the width of the post and one that allows for one-third of the post to be underground when installing steel posts. Then, fill the bottom of the hole with 6 inches of gravel and compact it with the end of a 4-inch by 4-inch piece of lumber. Center the post in the hole and press it firmly into the gravel. Use braces to hold the post in place and check with a level to ensure the post is straight.
Fill the hole with dry fast-setting concrete mix, allowing approximately 4 inches of space at the top of the hole. Add 1 gallon of water to the hole for every 50 pounds of fast-setting concrete mix in the hole. Allow the mix to set for four hours before putting weight on the post.