Treat utility vaults, manholes and pits as permit-required confined spaces until the employer has evaluated them

OSHA lists underground vaults, manholes and pits as confined spaces. Before cabling or fiber crews enter one, the employer must have identified whether it is permit-required, and entrants need training, a permit, atmospheric testing and continuous contact with an attendant.

Source facts

OSHA’s Permit-Required Confined Spaces QuickCard describes a confined space as one with limited openings for entry or exit, large enough to enter and work in, and not designed for continuous occupancy, including underground vaults, manholes, pits and underground utility vaults. OSHA’s confined spaces page adds equipment housings, ductwork and tunnels to the examples.

A permit-required space may contain a hazardous atmosphere, material that can engulf an entrant, a converging shape that could trap or asphyxiate, or other serious hazards such as exposed live wires. The employer must identify these spaces and inform exposed employees of their existence, location and hazards.

The QuickCard tells workers not to enter a permit space without training and a permit to enter, to identify physical hazards before entry, and to test and monitor for oxygen content, flammability, toxicity or explosive hazards before and during entry. Entrants use the employer’s fall protection, rescue, air-monitoring, ventilation, lighting and communication equipment and maintain contact at all times with a trained attendant.

Applicability

Use this for any job that requires entering a space below grade or inside equipment. General industry, construction and maritime work have separate OSHA confined-space standards, and state-plan states such as Michigan enforce their own versions.

DSE recommendation

DSE recommends that no technician enter a vault, manhole or pit unless the employer’s confined-space evaluation and entry procedure for that space are on hand. Ask the facility owner or utility for known hazards and existing permit procedures, include a calibrated gas monitor, ventilation, retrieval equipment and an attendant in the job plan, and stop work if monitoring readings change during entry.

Verification

Before each entry, confirm the permit is completed, the gas monitor’s calibration and bump test are current, and the attendant and rescue arrangements are in place. Keep completed permits with the job record and review a sample each quarter.

Official references

OSHA — Permit-Required Confined Spaces QuickCard (OSHA 3214). OSHA — Confined Spaces. Reviewed October 18, 2026.