Dielectric Testing for Bucket Trucks & Aerial Lifts

ANSI and OSHA: The Basics

Anyone who operates a bucket truck, aerial lift, or other insulated aerial device is required to have it dielectrically tested every year. ANSI A92.2 — adopted by OSHA — mandates annual dielectric testing for any vehicle-mounted aerial lift carrying an insulation rating, even if the equipment never operates directly on energized lines. Bona Bros. is one of the few shops in the Twin Cities equipped to perform this testing in-house, and one of even fewer that can test, identify a problem, and repair it without sending the truck to a second vendor.

What Dielectric Testing Covers

Dielectric testing measures the electrical insulation integrity of an aerial device's insulating components. We test both the AC and DC insulating systems on the boom, the upper and lower boom inserts, and the fiberglass sections and liners that protect the operator from contact with energized conductors. We also check the integrity of hydraulic hoses, control lines, and any electrical wiring that crosses the insulated section — a single compromised crossing can defeat the entire insulating system, regardless of how sound the boom itself is. Testing is conducted under controlled voltage in accordance with ANSI A92.2 procedures, with documentation provided for your compliance records.

Why Annual Testing Is Required

ANSI A92.2 specifies that insulated aerial devices must be dielectrically tested at intervals not exceeding 12 months. OSHA enforces compliance under 29 CFR 1910.67 and 29 CFR 1926.453. Equipment that hasn't been tested within the prior year cannot be used for energized line work, and operators using untested equipment expose themselves and their employers to significant liability — both regulatory and in the event of an incident. Annual testing is also a precondition of most utility, telecom, and municipal service contracts.

Test and Repair Under One Roof

Most shops that perform dielectric testing don't repair what they find. If a boom fails, a liner cracks, or a hose has worn through its insulating jacket, the truck goes to a second vendor for remediation — then back to the testing shop for retesting. Bona Bros. is equipped to handle both. Our technicians are trained in aerial lift hydraulics, electrical systems, and fiberglass repair, and we can move directly from test results into repair without coordinating a second shop or a second trip. For fleets running multiple insulated trucks, this consolidation matters at scale.

Multi-Unit Fleet Testing

We schedule fleet-wide dielectric testing for utility contractors, municipal departments, telecom operators, tree services, and any organization running more than one insulated aerial device. We work around your operations calendar — testing in batches to minimize downtime, prioritizing units approaching their compliance deadline, and coordinating with your ANSI inspection cycle so a single visit covers both annual requirements. Multi-unit pricing is available; contact us for a quote on your full fleet.

What happens if my equipment fails dielectric testing?

If the test identifies a failed liner, compromised insulation, hose crossing, or other defect, we provide a written report identifying the failure point and the repair required. Because we're equipped to perform aerial lift hydraulic and electrical repairs in the same facility, we can move directly into remediation and retest the unit before it leaves the shop. Most repairs are completed within the same visit when parts are on hand.

How long does dielectric testing take?

A standard single-unit dielectric test takes 2 to 4 hours depending on the equipment's complexity — a service body bucket truck moves faster than a multi-section material handler. Multi-unit fleet testing is scheduled in batches to minimize total downtime; we work with you to sequence units around your operations calendar.

What documentation do I receive after testing?

Every unit tested receives a signed test certificate documenting the date of test, the equipment's identifying information, the voltage applied, and the pass or fail result for each insulating component. The certificate satisfies ANSI A92.2 and OSHA recordkeeping requirements and serves as proof of compliance for utility, telecom, and municipal contract audits.

What's the difference between an ANSI inspection and dielectric testing

ANSI inspections evaluate the overall mechanical condition, hydraulics, structure, and operational safety of an aerial lift. Dielectric testing specifically measures the electrical insulation integrity of insulated equipment. ANSI A92.2 requires both annually for insulated aerial devices — they're complementary, not interchangeable. We perform both at our New Brighton facility.