This week’s question was submitted by one of our forum members.

When performing an arc flash study, what is the most common code violation found?

Incorrect Protection of Conductors/Equipment
Inadequate Short Circuit Interrupting Ratings
Other Violations (Please Specify)
None – It is all perfect!

In addition to NEC article 110.9 & 110.10 violations, I found NEC 110.26 violation frequently. Sometimes, the panels are hidden behind boxes, ladders, cupboards, etc that we don't even see it, let alone leaving adequate working space per Table 110.26(A)(1).

We see all kinds of violations including holes in gutters, panels, open junction boxes, conduits with energized wire hanging out, incorrect labeling or no labels on gear. Gear with too many main breakers or disconnects. Undersized wire or oversized breakers to transformers, no secondary OC protection on transformers or too high an amperage breaker or fuse to protect transformer secondaries. Places where maintenance was let go. Where new work was installed by people hired to do maintenance. Not that the maintenance people did a poor job, but they are often asked to do maintenance as well as hook up machines or install new work without being given the proper tools and equipment to do the work. Finally, where the authority having jurisdiction either wasn't up to the task of inspecting or where they failed to properly inspect.

This topic almost (and I do mean almost) borders on the humorous.....but only at times. The previous posts have cited several of the issues which I commonly see. But in addition to those- 110.14(C) is commonly violated, 110.26 (B)-including the storage of flammable materials ON TOP OF electrical equipment such as transformers, mixing of Essential Systems branch circuits with normal power, in hospitals, Life Safety and normal power circuits in many other locations.
Many of the institutions I have been to, and some are fairly large, have no real AHJ. They honestly believe that inspections do not apply to them as they are only doing "maintenance". Quite often though they will install new circuitry and equipment requiring installation of new conduit, wiring, disconnects and OCPDs. Invariably they get one or more parts of that design incorrect, and there is no one there more knowledgeable than they are themselves to catch their errors. And when they have outside contractors come in to perform more extensive installations or modifications, they have no clue as to whether or not it is correct. Often I see them being performed without city, county or other jurisdictional permitting and oversight. Forget federal and state.

Working space requirements are the most common violations I find.

I'm not absolutely sure when it changed but I believe that the working space requirements might have changed over time. A lot of older equipment definitely follows different distances.

Agree. The working space has evolved over the ages. One of the significant changes that impacted a lot of installations was the equipment extending more than 6 inches in front of other equipment in the same vertical space. The 1996 NEC permitted equipment of equal depth in the same vertical space and it changed to 6 inches in the 1999 NEC (110.26(A)(3)).

Many of the airfield lighting vaults I visit have had equipment added over the years without regard to adequate working space. Many are not an inch or two out, but gross violations.

Besides many violations for under-rated equipment, almost universally a lack of service, maintenance, or record there of if such service/maintenance has occurred.