1910.146 — the vault is a confined space.
Confined space is usually treated as a chemical-plant problem. On a data center campus the highest-consequence permit space is an electrical vault, and it is regularly entered as if it were a room.
First: is it a confined space? Large enough to enter and perform work, limited or restricted means of entry or exit, and not designed for continuous occupancy. Second: does it contain a permit hazard? Hazardous atmosphere, engulfment potential, internal configuration that could trap or asphyxiate, or any other recognized serious hazard. Both yes means permit-required.
§ Data center spaces to evaluate
| Space | Confined? | Likely permit hazard |
|---|---|---|
| Electrical vault / manhole | Yes | Oxygen deficiency, accumulated water, and energized medium-voltage cable — "any other recognized serious hazard" |
| Valve pits | Yes | Oxygen deficiency, engulfment from a line failure |
| Cooling tower basin | Yes | Engulfment, biological (Legionella), rotating equipment, chemical treatment |
| Thermal energy storage tanks | Yes | Engulfment, oxygen deficiency, cold |
| Fuel tanks and vaults | Yes | Flammable atmosphere, oxygen deficiency |
| Duct bank pull boxes | Usually | Atmosphere, water, energized cable |
| Large air handler plenums | Sometimes | Rotating equipment, restricted egress, thermal |
| Under-floor plenum (deep raised floor) | Evaluate | Restricted egress, atmosphere during agent discharge |
The employer must evaluate the workplace to determine whether it contains permit spaces. A site with no confined space inventory has not met the first requirement of the standard, regardless of whether anyone ever enters one.
§ Where confined space meets electrical
The Eversource case is the canonical example — a vault entry where OSHA cited failure to test oxygen levels before entry, on a job that was also an electrical job. That case straddles two disciplines, and the sites that get it wrong are usually the ones where the electrical team owns the vault and the safety team owns the confined space program, and neither owns the entry.
The correct arrangement: a vault entry is simultaneously a permit-required confined space entry under 1910.146 and electrical work under 70E. It needs an entry permit and, if the cable is not in an electrically safe work condition, an energized work permit as well.
Note also that the 130.2(A)(2) additional person and the confined space attendant are different roles with different requirements. One person may not be able to do both — the attendant cannot leave the entry point, and the additional person must be positioned outside the electrical boundaries.
§ Program elements
- Identify and evaluate permit spaces; inform employees by signage or other equally effective means.
- Written permit space program if entry is allowed.
- Entry permits — atmospheric testing before and during entry, isolation, ventilation, rescue provisions.
- Roles — authorized entrant, attendant, entry supervisor, each trained.
- Rescue — non-entry retrieval where feasible; if you rely on the fire department, you must have confirmed they will respond and are equipped.
- Contractor coordination — the host must inform the contractor of the space and the hazards, and debrief afterwards.
Rescue plans that name the local fire department without anyone ever having confirmed the department will perform a confined space rescue at that address. On a remote campus with a volunteer department this assumption has killed people.
Breadth matters here
A CSP who teaches 70E and also owns the confined space, fall protection and hot work programs — because in a vault they all apply at once.
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