Square Shaft (SS) and Round Shaft (RS) Lead Sections
The first section or lead section contains the helical plates. This lead section can consist of a single helix or up to four helices. Additional helices can be added, if required, with the use of helical extensions. Standard helix sizes are shown in the table to the right. The helices are arranged on the shaft such that their diameters increase as they get farther from the pilot point. The practical limit on the number of helices per anchor/pile is four to five if placed in a cohesive soil and six if placed in a cohesionless or granular soil.
Plain extensions are then added in standard lengths of 3, 5, 7 and 10 feet until the lead section penetrates into the bearing strata.