EHAP field rules

Working near power lines: OSHA, ANSI Z133 & site setup

The OSHA rules and ANSI Z133 requirements for tree work near power lines, how to identify lines, and how to set up the site: cones, signs and truck position.

OSHA regulations that apply

Rule	Who it covers	Key points
29 CFR 1910.269 (line-clearance tree trimming)	Line-clearance arborists working for or under contract to a utility	Training and qualification, minimum approach distances, job briefings before each job, two trained workers near lines over 750 V, insulated tools and aerial lifts, fall protection in buckets.
29 CFR 1910.331–.335 (electrical safe work practices)	Non-qualified tree workers and general tree care	Keep at least 10 ft from overhead lines up to 50 kV, plus 4 in for every 10 kV above that. Use conductive tools and equipment only when they can't break that distance.
29 CFR 1910.67 (vehicle-mounted aerial devices)	Bucket trucks	Only trained operators, test lift controls every day, wear a body harness and lanyard attached to the boom or bucket, set brakes and use wheel chocks.
29 CFR 1926 Subpart CC (cranes)	Crane-assisted tree removal	Treat lines as energized, set an encroachment boundary (20 ft for up to 350 kV), use a dedicated spotter and a planning meeting with the utility.
OSHA General Duty Clause	All employers	Recognized hazards such as conductors in the work zone must be controlled even when no specific rule applies.

Read the current eCFR text at osha.gov. Your state may run its own OSHA program with stricter rules.

ANSI Z133 requirements near power lines

Only qualified line-clearance arborists or trainees under direct supervision may work closer than the minimum approach distance (MAD).
Non-qualified workers keep themselves, tools, ropes and the tree at least 10 ft (3.05 m) from conductors.
Do a job briefing before every job that names the electrical hazards, the voltage, the MAD and who is qualified.
Treat every conductor as energized, including telephone and cable lines and service drops.
Use only insulated aerial lifts and dielectric-tested tools inside the MAD, and keep them clean, dry and tested on schedule.
Never use a climbing line or ladder where it could touch a conductor. Don't climb a tree with branches in contact with a line.
Two qualified workers must be in voice range when one works near conductors over 750 V.
Have someone trained in aerial rescue and CPR on site whenever crew work near power lines.

Z133 sets the minimum. The utility's rules and the job briefing can be stricter, never looser.

Power line identification

Line	Where it is	What to look for
Transmission	Tall steel towers or monopoles	Long insulator strings, bundled wires, wide cleared corridor. 69 kV to 500 kV+.
Primary distribution	Top of a wood pole	Wires on pin or post insulators, transformers and cutouts nearby. 4 kV to 34.5 kV.
Neutral	Just below the primaries	Single bare wire close to the pole. Can still carry current.
Secondary / service drop	Mid pole to the building	Triplex: insulated wires twisted around a bare messenger. 120/240 V and still deadly.
Communications	Lowest on the pole	Black bundled cable on a messenger. Treat it as energized — it can be crossed with a live line.
Guy wires	Diagonal to the ground anchor	Steel cable. It can become energized if a line faults.

Count insulator discs: about 10–15 kV each. When unsure, assume the higher voltage and call the utility.

Jobsite setup: cones and signs

Traffic setup follows the MUTCD (Part 6) and your state DOT or permit. These are typical short-term layouts.

Before any cones: park, set brakes, chock wheels and put on Class 2 or 3 high-visibility vests.
Advance signs in this order: "Road Work Ahead", "Tree Work Ahead" or "Utility Work Ahead", then "Be Prepared to Stop" or a flagger sign.
Sign spacing: about 100–350 ft apart on low-speed streets, 500 ft on 40–45 mph roads and 1,000 ft or more on highways.
Taper length in feet ≈ lane width × speed for 45 mph and up (for example 12 ft × 50 mph = 600 ft). Below 45 mph use width × speed² ÷ 60.
Put cones at a spacing in feet roughly equal to the speed limit in mph across the taper, and about twice that along the work area.
Leave a buffer space between the taper and the first truck. Never let anyone use it for parking or brush.
Use 28 in cones, reflective when working at night. Add a flagger with a STOP/SLOW paddle whenever traffic must alternate.
Close the drop zone with cones and tape on the sidewalk, and post a spotter to keep people out.
Pick up cones in the reverse order you placed them — work area first, advance signs last.

Truck and bucket positioning near lines

Look up before you park. Position the truck so the boom never has to swing over or under conductors to reach the work.
Park on firm, level ground with outriggers on pads. Stay off manholes, soft lawns and curbs.
Set the parking brake, chock wheels and ground or barricade the truck as the utility requires.
Mark an equipment exclusion zone around the truck with cones. Nobody on the ground touches the truck while the boom is near lines.
Keep the chipper away from the lines and downwind of traffic. Feed from the curb side, not the traffic side.
Use a dedicated spotter whenever the boom, crane or load line might come within the MAD.
If the truck contacts a line: stay on the truck. If fire forces you off, jump clear with feet together and shuffle away. Never touch the truck and ground at the same time.

Rule of thumb: if you can't reach the work without crossing a conductor, the setup is wrong. Move the truck.

Job briefing checklist near power lines

Voltage of every line and the MAD for each worker.
Who is qualified, who is a trainee and who must stay out.
Utility contact, outage or cover-up arrangements and the work order number.
Traffic setup, drop zone and truck position.
Emergency plan: aerial rescue person, 911 address, nearest hospital, utility emergency number.

Cautions

This is training and awareness material. OSHA regulations, ANSI Z133, the MUTCD and the utility's own rules are the final word.
Only qualified line-clearance arborists may work inside the minimum approach distance.
If a line is down or touching a tree, clear the area and call 911 and the utility. Don't approach it.