Job Site Safety
Mixed-voltage reality of CP work
Cathodic protection is described as low-voltage DC work, but a CP tester routinely stands in front of a rectifier cabinet fed at 120, 240, or 480 VAC. Before opening any cabinet, apply lockout/tagout, verify the meter on a known live source, and treat the AC supply, the DC bus, and any capacitors or batteries as separate hazards. Personal protective equipment normally includes safety glasses, appropriate gloves, and arc-rated clothing where the equipment label justifies it.
Buried and confined hazards
Locate all buried utilities before driving reference-electrode stakes, deep wells, or anode rods; excavation deeper than 1.5 m (5 ft) requires a protective system. Test stations in vaults and manholes are confined spaces: test oxygen, flammables, and hydrogen sulfide before entry, and ventilate. Impressed-current anodes generate hydrogen, so never assume a vault is safe because it "looks dry."
Energized-until-proven
Rectifier off does not mean structure de-energized. Bonds, galvanic anodes, telluric currents, DC transit stray current, and AC induction from parallel power lines all remain. Coated pipelines sharing a corridor can carry induced AC well above 15 V to remote earth.
Traps: calling a 12 V DC output "harmless" while ignoring the AC feed; assuming a de-energized pipe after interrupting the rectifier; skipping gas testing in a vault. Rule of thumb: any metallic structure you did not personally bond to earth is energized until you measure it.
Worked example: a technician opens a rectifier without LOTO because "the breaker is right there." Correct practice: open the breaker, lock it, verify zero energy at the terminals with a rated meter, then work.