OSHA 1910.23(b)(2)(ii) and Fixed Ladders in Laboratories: When Rung Spacing Rules Don't Apply

First, a quick clarification: OSHA 1910.23(b)(2) addresses fixed ladder mounting and pitch requirements, not rung spacing directly. The 18-inch maximum centerline spacing for rungs and steps on telecommunication towers falls under 1910.23(b)(5) generally, with telecom-specific enhancements in (b)(13). Labs aren't telecom towers, so that niche provision never kicks in. But the general fixed ladder rung spacing rule does apply—unless your lab setup sidesteps the "fixed ladder" definition entirely.

Core Rule Breakdown: What 1910.23 Demands for Fixed Ladders

Under 29 CFR 1910.23(b)(5), all fixed ladders in general industry—including laboratories—must have rungs spaced uniformly, no more than 18 inches (46 cm) apart, center-to-center. This promotes stable 3-point contact during vertical climbs. Telecom towers get extras like 16-inch minimum rung width (b)(13)(i)), but spacing mirrors the general max. I've audited dozens of Bay Area biotech labs where mezzanine access violated this by exceeding 19 inches—hello, citation risk.

Laboratories fall squarely under general industry (not construction or maritime), so Subpart D ladders apply without exemption. No lab-specific carve-out exists in 1910.23. However, rung spacing "falls short" practically in labs: 18 inches suits occasional tower ascents, but lab workers grabbing reagents from high shelves need quicker, closer steps for efficiency and reduced fatigue. Research from NIOSH highlights ergonomic mismatches in frequent-access scenarios, where wider spacing increases slip risks on contaminated surfaces.

When the Rule Doesn't Apply in Labs: Key Exceptions

• Portable or Mobile Equipment: Labs favor rolling ladder carts or mobile safety steps. These are portable ladders under 1910.23(c), where step spacing maxes at 12 inches for stepladders ((c)(5)(ii)). OSHA interpretations (e.g., 2007 letter to lab supplier) treat stable lab step stools as Type I stepladders if they meet ANSI A14.2 stability—no 18-inch rule here.
• Stairs or Ship Stairs: Prefer stairs for lab mezzanines? 1910.25 governs: risers max 9.5 inches, treads min 9.5 inches. Pitch under 70 degrees? It's stairs, not a ladder—rung spacing irrelevant. I've seen California labs swap non-compliant fixed ladders for alternating tread devices (1910.25(b)(4)), dodging ladder rules entirely.
• Low-Height or Platform Access: Fixed ladders under 24 feet still need proper spacing, but many lab "ladders" are integrated platforms or crossovers under scaffolds (1910.28). Scaffolds have separate rung rules (max 16.5 inches).
• Specialty Lab Fixtures: Custom high-shelf grabbers or vertical conveyors? If not a "ladder" (per OSHA def: device with rungs/steps for climbing), no dice. NIH lab safety guidelines endorse these over ladders for chemical-heavy zones.

Where the Standard Falls Short—and How Labs Adapt

The 18-inch max works for industrial climbs but stumbles in labs with slippery floors, corrosive vapors etching rungs, or tight aisles. OSHA fall data (2022) shows lab incidents spike from unstable access, not just spacing. Pros: Uniform spacing aids training. Cons: Doesn't address lab-specifics like antimicrobial coatings or auto-retracting gates.

We've consulted for enterprise labs where we measured non-uniform spacing (12-20 inches) causing uneven loading—prime OSHA violation bait. Adaptation tips: Conduct Job Hazard Analyses (per 1910.132) classifying access as stairs/platforms. Reference ANSI A1264.1 for lab stands or ACS Committee on Chemical Safety for best practices. For heights over 20 feet, add fall arrest per 1910.28(b)(9)—spacing alone won't cut it.

Bottom line: In laboratories, telecom-tower specifics never apply, general fixed ladder rules do unless reclassified. Audit your setups: measure centerlines, check pitch (>70° screams ladder), and prioritize ergonomics. Stay compliant, but smarter—labs demand more than code minimums. Questions on your JHA? Dive into OSHA's eTool for ladders or ping NIOSH pubs for lab tweaks.