Digger Derricks & Utility Line Trucks

Digger derricks are truck-mounted machines with a boom, a winch and an auger. Utility crews use them to dig pole holes and set, move and remove poles, often near energized power lines. Electrocution is the biggest danger, followed by tip-overs, crushing from poles and entanglement in the auger.

• Line Crews
• Telecom Crews
• Digger Operators
• Utility Contractors

How digger derricks work

• A digger derrick (also called a line truck with a derrick) has a telescoping boom with a hoist and a hydraulic auger or a pole grapple. Outriggers stabilize the truck.
• OSHA covers them in 29 CFR 1910.269 (electric power generation, transmission and distribution) and, in construction, 29 CFR 1926 Subpart V and the cranes rule's provisions for digger derricks used in power line work. Rules differ by the type of work, so follow your employer's program and the manual.
• Only qualified, trained operators should run them, and crews working near energized lines must follow the electric utility's safe work rules. See Power Line Workers.

Main hazards

• Electrocution: contact between the boom, line or pole and an energized conductor. The truck and ground around it can become energized. See Overhead Power Lines and Equipment Contact With Power Lines.
• Tip-over: overloading, soft ground, poor outrigger setup, and side loading.
• Pole and boom strikes: poles swing, roll or drop, and can crush workers on the ground or in the bucket.
• Auger hazards: entanglement in the rotating auger and drill rod, and crushing from kickback when it hits a rock.
• Underground utilities: drilling into gas, electric, water or communication lines. See Utility Strikes and Call 811.
• Traffic and struck-by in roadside work. See Work Zones.
• Hydraulic hazards and pinch points at outriggers and boom joints. See Hydraulic Hazards.
• Falls when climbing on and off or working at height.

Working near power lines

• Treat every line as energized until the utility says it's dead and it's tested and grounded. Know the voltage and the required minimum approach distance (MAD). For general equipment, OSHA's cranes rule requires at least 20 feet for lines up to 350 kV, and utility work follows 1910.269 tables, which differ for qualified workers with proper tools and training. See Cranes & Power Lines.
• Use a spotter or signal person dedicated to watching clearances, and set up the truck so the boom won't swing into lines. Consider cover-up (insulating blankets) and de-energizing where required.
• Ensure the insulating boom or boom tip components are in good condition and tested as required. Don't rely on them to protect you if they're dirty, damaged or wet.
• Use grounding where the utility's procedures require, and treat the truck as potentially energized. If the boom contacts a line, stay on the truck unless there's a fire, don't touch the truck and the ground at the same time, and warn others to stay away. If you must leave, jump clear with feet together and shuffle away. Call the utility and 911.
• Set up an equipotential zone and keep people out of the area around the truck during an energized line contact.

Setup and operation

• Do a pre-use inspection: boom, cables, hooks, winch, outriggers, auger, controls, alarms, lights and leaks.
• Set up on firm, level ground with outriggers fully extended as the manual requires, on pads or mats if soft. Block wheels and set the brake.
• Know the load chart, the pole weight and the radius, and stay within rated capacity. Don't side-load the boom or drag poles.
• Use slings and grapples rated for the pole and attach them properly. Use tag lines. Keep people out from under the pole and its swing path. See Rigging Basics.
• Set the pole slowly, plumb it and keep the boom load until the pole is secure and tamped or braced as required. Don't climb a pole that isn't stable.
• Use proper hand signals and radios between operator, ground crew and bucket workers. See Crane Hand Signals.

Drilling holes

• Locate and mark utilities (call 811 and potholing where needed) before drilling. Use hand digging near marked lines.
• Keep everyone away from the rotating auger and drill rod. Don't wear loose clothing, don't reach near the auger and don't step over it. Stop the auger to clear soil using a shovel or tool, not hands.
• Be ready for kickback when the auger hits rock or roots. Use controlled speeds and keep your hands and body out of the swing zone.
• Cover or guard open pole holes and mark them to prevent falls. See Holes & Floor Openings.

Digger derrick checklist

• I treat every line as energized and have a spotter watching clearances
• Outriggers are fully extended on firm ground and loads are within the chart
• Poles are rigged with rated slings and tag lines, and nobody is under them
• Underground utilities are located before drilling, and the auger area is clear
• The crew knows what to do if the boom contacts a line

Last updated: October 5, 2026