How much space is there around electrical equipment in your facility? Once you walk into almost any facility and start measuring, it likely won’t take long before your answer becomes, “Not enough.”
How much is enough? A common misunderstanding is that as long as you have about three feet of space in front of the equipment, then all is well. A corollary is that it’s better to stack boxes on top of transformers rather than in front of them.
The reality is that OSHA and the NEC require various space minimums not just in front of equipment, but also in other dimensions. The idea of “about three feet” is a misinterpretation of one of the several minimum space requirements. Depending upon the application, the minimum space in one direction might be eighteen feet.
OSHA provides the minimum space requirements in 29CFR1926, Subpart K. Here’s a short explanation of what “29CFR1926” means. Title 29 of the Code of Federal Regulations is under the purvey of the Department of Labor. The Occupational Safety and Health Administration occupies Parts 1900 through 1999 of the CFR. Part 1926 provides requirements for the construction industry in 26 Subparts labeled A through Z. Subpart K is for the electrical industry.
In Subpart K, you’ll find charts that show minimum working clearances, minimum depth of clear working space, and minimum elevation of unguarded energized parts above the working space.
OSHA turns the spacing requirements of the NEC, Article 110 into federal law.