October 6, 2026
This week’s photo is courtesy of- GeoLog, LLC, Cottonwood, AZ, USA.
Safety Focus
Part 2 of 4: Overhead Power Lines and Mast Raising: Spot It
NIOSH's new overhead power line guidance, published in August 2026, opens with two words: "Look Up!" Locate the lines before work starts. That sounds obvious. Monday's cases say it is not.
You cannot tell voltage by looking. A line that looks small can still carry thousands of volts. OSHA's construction equipment rule, 1926.600(a)(6)(vi), is clear: "Any overhead wire shall be considered to be an energized line unless and until the person owning such line or the electrical utility authorities indicate that it is not an energized line and it has been visibly grounded." The rule accepts that word from the line's owner or the utility. Make it crew policy to get it from the utility, and never from someone who just says the line has been dead for years.
You do not have to touch it. High voltage can jump, or arc, across open air. That is why every clearance rule gets bigger as voltage goes up. The danger zone is a bubble around the line, not the wire itself.
Distribution lines kill, not just big towers. The two cases from Monday involved 7,200-volt and 12,000-volt lines, the kind that run down a county road or across a yard.
Wells and power live together. A well with a pump needs power, so lines often run close to the wellhead. In the California case, the line ran directly over the well shack. Pump pulling jobs put a hoist right under that service.
Picture the whole arc, not just the final height. A mast raised from a rear pivot sweeps through an arc on its way up. In the Alaska case, the truck was parked under the lines, and the mast rose right between them. Check the full swing and the full raised height against every line in the area, and remember lines sag on hot days and sway in wind.
Key Takeaways:
• Treat every overhead line as energized until the utility says it is dead and visibly grounded.
• Electricity can arc to equipment that never touches the wire.
• Common 7,200 to 12,000-volt distribution lines have killed drilling crews.
• Check the mast's full arc and full height, not just where the truck sits.
Sources:
• OSHA: 29 CFR 1926.600, Equipment
• NIOSH (California FACE Program): Two Well Drillers Electrocuted When Their Truck-Mounted Boom Contacts Overhead Power Lines
• NIOSH (Alaska FACE Program): Driller's Helper Electrocuted When Mast of Drill Rig Contacted Overhead Power Lines
Knowledge Share
Part 2 of 4: Subsurface Geology Analysis: Understand It
Think of each log as a witness. Each one saw the formation from a different angle, and none of them tells the whole story alone.
The driller's log. Depth, material, color, grain size, and how the hole drilled: penetration rate, chatter, lost circulation, first water. It is the only witness that held the formation in its hand.
Natural gamma. The probe counts natural gamma radiation from the formation. EPA's technical guidance explains that clays contain gamma-emitting potassium and tend to concentrate uranium and thorium, so clay reads high and clean sand reads low. It works in open holes and through PVC or steel casing, in air, water, or mud.
Normal resistivity. Resistivity is how strongly the formation and its water resist electric current. The USGS notes the short-normal and long-normal probes use 16-inch and 64-inch electrode spacings. Clay reads low, because of the water bound up in it. Permeable fresh-water sand reads higher. Salty water drives resistivity down.
Spontaneous potential (SP). SP records the small natural voltages that develop between the borehole fluid and the surrounding formation. The Bureau of Reclamation's field manual puts it simply: SP and resistivity curves converge opposite shale and diverge opposite permeable fresh-water sands.
Caliper. It measures hole diameter. Reclamation calls it "one of the most useful and simple of all logs." Washouts and caving can distort the readings of other logs.
The catch: SP and normal resistivity need an open hole filled with water or mud. Once casing goes in, they are done. Gamma still works through casing, and an electromagnetic induction log can read through PVC. Plan the logging run before you case.
What to check before you order:
• Run SP and resistivity before casing goes in. You do not get a second chance.
• High gamma plus low resistivity points to clay. Low gamma plus higher resistivity points to clean sand.
Sources:
• U.S. EPA (CLU-IN): Gamma Logging
• Bureau of Reclamation: Engineering Geology Field Manual, Vol. 2, Ch. 14: Borehole Geophysical and Wireline Surveys
• USGS (Keys, TWRI 2-E2): Borehole Geophysics Applied to Ground-Water Investigations
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