110.34 - Work Space and Guarding: Don't Get Bit by the Big Stuff

The Real Deal

Alright, listen up. You know how we're always harping on about working space around panels and gear? Well, when you step up to high-voltage equipment (over 1000V AC or 1500V DC), the code doesn't mess around. This ain't your grandma's 120/208 panel—this is the stuff that'll turn you into a smoking pair of boots if you screw it up.

110.34 is basically saying: "Give yourself enough room to work without becoming a crispy critter, and keep the idiots out."

(A) Working Space - AKA "Don't Work in a Broom Closet"

Any equipment that you might need to poke, prod, adjust, or cuss at while it's still hot needs clear working space in front of it. And I mean CLEAR—not "kinda clear except for that ladder and some conduit and Steve's lunch box." The floor needs to be level too, because trying to troubleshoot 13.8kV gear while standing on a stack of plywood isn't just stupid, it's code-illegal stupid.

The distances? Check out Table 110.34(A). It's like a menu at a restaurant where everything on it can kill you:

Condition 1 (safest): Live parts on one side, nothing gnarly on the other = smallest clearance
Condition 2 (spicier): Live parts on one side, grounded stuff (like concrete walls) on the other = more clearance
Condition 3 (you're in the danger zone): Live parts on BOTH sides = maximum "oh crap" distance

And yes, those concrete, brick, or tile walls? The code considers them grounded. Because physics doesn't care about your opinion.

Here's the beautiful exception: You don't need working space behind switchgear or control assemblies IF there's nothing back there that needs servicing (no fuses, no switches) AND you can reach all the connections from somewhere else. But if you need to get back there for non-electrical stuff, you still need 30 inches. Even the code knows nobody wants to be stuck behind a 2000-amp beast doing the electric slide.

(B) Separation from High-Voltage Equipment - The "Don't Mix the Kids with the Adults" Rule

Got low-voltage stuff (under 1000V AC/1500V DC) sharing space with the big boys (over 1000V)? You better separate them with a partition, fence, or screen. Think of it like keeping the 120V stuff away from the 13.8kV gear—they shouldn't be socializing.

Exception: If the low-voltage equipment is ONLY serving stuff in the high-voltage room, and only qualified people can get in there, you can skip the partition. It's like saying, "If everyone in the room knows what they're doing, we can relax... a little."

(C) Locked Rooms or Enclosures - The "Keep Out, Seriously" Rule

This one's simple: If there are exposed live parts or conductors, LOCK THE DAMN DOOR. Unless you've got a qualified person playing security guard 24/7, it stays locked.

And you need a sign that says:

DANGER — HIGH VOLTAGE — KEEP OUT

Not "Caution - Might Tickle a Bit." Not "Please Be Careful." DANGER. Make it permanent and obvious—like your uncle's bad tattoos, but more useful.

(D) Illumination - Because Working in the Dark is for Morons

You need lights in these spaces. REAL lights. And here's the kicker—they can't be on automatic-only control. Why? Because Murphy's Law says those motion sensors will shut off right when you're elbow-deep in 4160V gear, and then you'll do the electric boogaloo.

The lights need to be positioned so you're not reaching over live parts to change a bulb. Because explaining to OSHA how you got electrocuted changing a light bulb is a conversation nobody wants to have.

The light switches also need to be located where you won't accidentally grab something energized while reaching for them. "Hey, is the light switch the thing that just bit me?" is not how you want your day to go.

(E) Elevation of Unguarded Live Parts

There's a whole table (110.34(E)) about how high unguarded live parts need to be above the working space. Basically, "If we can't put a fence around it, we'll put it way the hell up there where you can't accidentally touch it." Check your code book for the exact heights—they vary by voltage.

(F) Protection of Service Equipment - Keep the Plumbers Out

No water pipes, steam pipes, or other "foreign systems" near your high-voltage gear unless they're for fire protection. Because the only thing worse than working on 13.8kV equipment is working on 13.8kV equipment while it's raining indoors.

If you MUST have pipes nearby, protect your gear from leaks and condensation. Nothing kills a $100,000 switchgear lineup faster than a leaky pipe and gravity.

Key Takeaways (The Stuff That'll Save Your Bacon)

Working space is MANDATORY in front of equipment that might need service while energized—check Table 110.34(A) for exact distances based on voltage and conditions
Condition 1, 2, or 3? Know the difference:
- Condition 1: Live on one side only (or guarded on both)
- Condition 2: Live on one side, grounded on the other
- Condition 3: Live on both sides (pucker factor: maximum)
Floor must be clear, level, and flat for the entire depth and width of the working space—no excuses, no exceptions
Rear access exception: No working space needed behind gear with no serviceable parts AND connections accessible elsewhere (but 30" needed for non-electrical work)
Mix voltages? Separate them. Low-voltage and high-voltage equipment need barriers unless serving only high-voltage equipment in qualified-only spaces
Concrete, brick, and tile walls = grounded for working space calculations
Lock all doors to rooms with exposed high-voltage unless constantly attended by qualified personnel
Required signage: "DANGER — HIGH VOLTAGE — KEEP OUT" (permanent and conspicuous per 110.21(B))
Lighting is required and cannot be automatic-only—must have manual control
Light fixtures and switches positioned so you're not reaching over live parts for maintenance
Keep foreign piping away from high-voltage gear (except fire protection systems)
Protect from leaks where foreign systems are nearby—water and high voltage don't play nice

Real-World Jobsite Scenarios

Scenario 1: The Packed Utility Room

You're doing a service call at a 30-year-old manufacturing plant. The 4160V switchgear is in a utility room that's become the "everything closet." There's HVAC ductwork, a janitor's mop bucket, spare parts for the production line, and someone's ancient office chair blocking the front of the gear.

The Problem: Even though you need 4 feet of working space (Condition 2—live parts on one side, concrete wall on the other), you've got maybe 18 inches of "squeeze yourself in sideways" space.

The Reality Check: This is a violation that's been waiting to kill someone for decades. You can't legally work on this equipment, and if you try and something goes wrong, your insurance company will laugh while denying your claim. Time for a come-to-Jesus meeting with the facility manager about clearing the space—and that chair's gotta go to chair heaven.

The Fix: Everything gets moved. Period. And stays moved. Paint a line on the floor if you have to. The gear was there first; everything else is trespassing.

Scenario 2: The DIY Lighting Catastrophe

You're called to troubleshoot a 13.8kV lineup that keeps tripping. When you arrive (after lockout/tagout, because you're not stupid), you discover the previous electrician installed motion-sensor-only lighting to "save energy."

The Problem: The lights kept shutting off during maintenance, so technicians were using flashlights and headlamps. Which is exactly how someone eventually dropped a flashlight and created a phase-to-ground fault that took out half the facility.

The Reality Check: Automatic-only lighting control in high-voltage spaces is explicitly prohibited. The lights need manual override at minimum. Working on high-voltage gear by flashlight is like juggling chainsaws while blindfolded—eventually, gravity and probability catch up with you.

The Fix: Rewire the lighting with manual switches (located where you won't brush against live parts while using them), and add a sign: "LEAVE THE LIGHTS ON DURING MAINTENANCE—Your life depends on it."

Scenario 3: The Low-High Voltage Mixer

You're bidding a job where the engineer specced a new 480V distribution panel to be mounted in the same room as existing 12.47kV switchgear. No partition. No fence. Just... coexisting.

The Problem: Low-voltage and high-voltage equipment sharing space without separation is a code violation under 110.34(B). Unless your 480V gear is ONLY serving equipment in that high-voltage room, you need a barrier.

The Reality Check: This is where apprentices and unqualified personnel get hurt. Someone goes to reset a breaker on the 480V panel and doesn't realize they're two feet from exposed 12.47kV bus. Proximity breeds familiarity, and familiarity breeds "Hey, watch this!" moments.

The Fix: Either install a proper partition (chain-link cage works great) or relocate the 480V panel. And lock that door—this room is qualified-personnel-only territory now.

Scenario 4: The Sign of the Times

You're inspecting a hospital's electrical room with a 10-year-old, sun-faded "Caution" sign on the door. Inside are exposed 4160V bus bars.

The Problem: The code requires "DANGER — HIGH VOLTAGE — KEEP OUT" signage that's permanent and conspicuous. "Caution" is what you put on a wet floor, not a room that contains enough voltage to turn you into plasma.

The Reality Check: In a lawsuit or OSHA investigation, inadequate signage means you KNEW it was dangerous but didn't properly warn people. That faded "Caution" sign is actually worse than no sign—it's evidence of negligence.

The Fix: New sign, proper wording, high-visibility. Stainless steel or quality plastic that'll last. And while you're at it, verify the door lock actually works—half the time these doors are "locked" with a bent coat hanger.

Scenario 5: The Leaky Pipe Special

You're energizing a new 13.8kV service, and during final walkthrough, you notice a condensate drain line from the building's HVAC running directly above the switchgear lineup. The mechanical contractor says, "It's fine, it never leaks."

The Problem: Famous last words. 110.34(F) explicitly prohibits foreign piping near high-voltage equipment unless it's for fire protection. And "never leaks" just means "hasn't leaked YET."

The Reality Check: When (not if) that drain line clogs, backs up, and dumps water all over $200,000 worth of switchgear, you'll be explaining to the owner why you didn't catch it during installation. Water + high voltage = very expensive fireworks, equipment damage, and possibly injuries.

The Fix: Reroute that pipe NOW, before energization. If the mechanical contractor complains, show them this section of the code and let them know their "it never leaks" pipe just became their "relocate it on your dime" pipe. Alternatively, install drip pans and routing shields (with drainage away from equipment), but rerouting is cleaner and safer.

What to Study (For the Test and Real Life)

Definitely Know Cold:

Table 110.34(A) - Memorize at least the common voltages:
- 1001-2500V: 3', 4', 5' (Conditions 1, 2, 3)
- 2501-9000V: 4', 5', 6'
- If you work in medium voltage regularly, memorize your specific voltage range
The three conditions - You WILL get a test question asking you to identify which condition applies:
- Condition 1 = live parts on one side only, or guarded on both
- Condition 2 = live parts on one side, grounded on other
- Condition 3 = live parts on both sides
Concrete/brick/tile walls are considered grounded - This trips people up on tests constantly
The exact wording of the required sign: "DANGER — HIGH VOLTAGE — KEEP OUT"
Automatic-only lighting is prohibited - Must have manual override or control
The 30-inch rear access exception for non-electrical work
Lock the door unless constantly attended by qualified personnel

Important Context:

Why different voltages need different distances: At higher voltages, arc flash boundaries are larger, and the consequences of mistakes are exponentially worse. The code builds in safety margins.
The difference between this and 110.26: Section 110.26 covers working space for equipment 1000V and under. Section 110.34 is the big brother for over 1000V. Same concepts, bigger consequences, larger distances.
Foreign systems definition: Anything not part of the electrical installation—plumbing, HVAC, steam, compressed air, etc. Fire protection systems get a pass because they're protecting the electrical equipment.

Test Question Traps:

Mixing up voltage thresholds: The breakpoint is 1000V AC / 1500V DC. Know that cold.
Confusing Conditions 1, 2, and 3: Practice scenario questions about what's on each side of working space
Forgetting the floor requirements: It's not just about clearance depth—floor must be level, flat, and clear
The rear access exception: Know when you DO and DON'T need working space behind equipment
Automatic lighting: They love asking if motion-sensor-only control is acceptable (it's NOT)

Practical Application Study:

Walk into any medium-voltage electrical room and practice:

Identifying which condition applies (1, 2, or 3)
Measuring the actual working space and comparing to table requirements
Checking if the floor is clear, level, and flat
Verifying proper signage and door locks
Looking for foreign piping or systems overhead
Testing lighting controls (manual override present?)

The Money Questions for Master's Exam:

"What's the minimum working space for 4160V equipment with live parts on one side and a concrete wall on the other?" (Answer: Condition 2, 5 feet)
"Can you install motion-sensor-only lighting in a high-voltage equipment room?" (Answer: No, automatic-only control is prohibited)
"What separation is required between 480V and 12.47kV equipment in the same room?" (Answer: Suitable partition, fence, or screen—unless 480V only serves equipment in that room AND only qualified personnel have access)

The Bottom Line

Section 110.34 is all about respecting the power you're working with. High voltage doesn't give warnings, second chances, or participation trophies. You get working space right, or you get a trip to the hospital (if you're lucky) or the morgue (if you're not).

The code isn't being paranoid—it's written in blood, sweat, and lawsuits. Every requirement here exists because someone, somewhere, learned the hard way that corner-cutting around high voltage is how you win stupid prizes.

Remember: Give yourself room to work, keep the unqualified people out, light it up properly, and keep the foreign systems foreign. Your spouse and kids want you coming home with all your original parts in working order.

Now get out there and give that high-voltage gear the respect (and working space) it deserves. And for the love of all that's holy, lock the door and put up the right sign.

Stay safe, stay legal, and stay away from live 13.8kV bus bars.