The concept of "working space" is commonly misunderstood, and consequently adequate working space is commonly not provided. OSHA provides tables with specific numbers, but it gets its numbers from the NEC. You will find this information in Table 110.26(A)(1) and in the various written requirements of 110.26(A) through 110.26(E).

If you look at Table 110.26(A)(1), it basically says you need a minimum of 3 ft of distance between exposed live parts on one side of the working space and grounded live parts on the other. It also says you need a minimum of 3 ft of distance between exposed live parts on both sides the working space, except when the voltage is greater than 150V. Then it's a minimum of 4 ft.

Amazingly, many facility planners extract from this that it would be nice to have pieces of electrical equipment about 3 ft apart, but not an inch more.

Yet the 3 ft minimum is often grossly inadequate. For example, do you really want a tech's backside only inches away from a 100kVA dry-type transformer vent? If the transformer is 3 ft from a panel, that's the situation you have when someone opens that panel for maintenance. It's unsafe.

Section 110.26 requires adequate safe working space, which may include enough space for test carts, maintenance equipment, lights, and multiple people.