What Medium Voltage Actually Means on a Spec Sheet

A commercial job posting says the crew will be pulling medium-voltage cable. A drawing set calls out medium-voltage switchgear. Nobody on the job says a number out loud, and the term never appears on anyone's license. So what is medium voltage, in volts, and why does the label change what the work involves?

Medium voltage is a system voltage class, not a product line and not a credential. The dividing line most commercial specs lean on comes from the National Electrical Code, which separates general-purpose wiring from equipment operating at more than 1000 volts alternating current, or 1500 volts direct current. The 2023 NEC gathered those requirements into Article 495, which replaced the older Article 490 and pulled in medium-voltage cord, cable, and motor rules that had been scattered across other articles. Above that line, a spec sheet calls it medium voltage.

In practice, the number that governs the work is not always 1000 volts. OSHA's general industry electrical rule, 29 CFR 1910.303(h), still sets its added requirements at over 600 volts nominal, and it scales them by bracket. Required working space depth runs from 3 feet in the 601 to 2500 volt range up to 12 feet above 75 kilovolts, with a minimum 6.5 feet of height and 3 feet of width, and at least one entrance 24 inches wide by 6.5 feet high. Live parts have to sit in vaults, rooms, or enclosures that only qualified persons can reach, or be metal-enclosed where unqualified people can get near them.

That word qualified is where medium voltage turns into a hiring filter. Under 29 CFR 1910.269, a qualified employee must be trained to distinguish exposed live parts from everything else, determine the nominal voltage of those parts, and hold the minimum approach distance for that voltage, which is 2.14 feet phase-to-ground in the 5.1 to 15 kilovolt bracket and 2.53 feet from 15.1 to 36 kilovolts. Employers document that training, which is why medium-voltage experience shows up as a screening line rather than a nice-to-have. The Bureau of Labor Statistics puts the 2025 electrician median at $63,190 a year, or $30.38 an hour, across 821,000 jobs, with 9 percent growth projected through 2035 on the strength of grid work and data center construction. That median is the all-electrician baseline, and medium-voltage scope is where the substation and data center hiring sits.

The common misconception is that medium voltage is a license class. It is not. No state licensing board issues a medium-voltage card, and no exam converts a journey-level electrician into a medium-voltage electrician. Qualification is determined by the employer, tied to specific equipment and specific tasks, and it does not travel: being qualified on 15-kilovolt switchgear does not make someone qualified on equipment in the next bracket up. The second misconception is in the word itself. Medium describes where the voltage sits on a scale, not how much hazard it carries.

If you are deciding whether to chase medium-voltage work, answer the money question before the technical one. Start with the AmpScouts Commercial Electrician Salary Guide to see what commercial and industrial scale actually pays, then work backward to which contractors in your market are staffing medium-voltage scope.