How Much Working Space Is Enough?

Jan 1, 2009 12:00 PM, By Mike Holt, NEC Consultant

Electrical raceways and cables not associated with the equipment in the dedicated space can still be located within the dedicated space. These aren't considered “equipment foreign to the electrical installation.”
Foreign systems can be located above the dedicated space if protection is installed to prevent damage to the electrical equipment from condensation, leaks, or breaks in the foreign systems (Fig. 4).
Sprinkler protection piping isn't permitted in the dedicated space, but the NEC doesn't prohibit sprinklers from spraying water on electrical equipment.
A dropped, suspended, or similar ceiling isn't considered a structural ceiling.

Electrical equipment rooms and enclosures housing electrical equipment or apparatus controlled by locks are considered accessible to qualified persons who require access [110.26(G)].

See the definition of “Accessible as it applies to equipment” in Art. 100.

Now you can answer the question of how much working space is enough — and you know that the correct answer depends on what space you're talking about, what equipment is in that space, and other factors. The distance tables in OSHA and in 110.26 are starting points, not maximums.

What you're really trying to do is ensure that the space around the equipment doesn't prevent the safe operation and maintenance of that equipment. Meet that goal, and you'll satisfy OSHA, the NEC, and your insurance company. None of these are concerned, however, with the efficiency of maintenance and operation.

Often, people want to reduce working space in a misguided effort to maximize revenue per square foot for the facility. The reality is that you maximize revenue per square foot only when you allow enough space for efficient operation, maintenance, and repair.