NEC 110.79 - Fixed Ladders: Don't Let Your Ladder Rot Out From Under You
The Plain-English Breakdown
Alright, gather 'round. This one's short and sweet—probably the shortest section you'll read all year. If you're installing a fixed ladder (that's a permanent ladder, not your Werner extension), it needs to be corrosion resistant. That's it. That's the whole enchilada.
Now, I know what you're thinking: "Why the hell is there a ladder rule in Article 110 about general electrical requirements?" Good question! It's because these fixed ladders give you access to electrical equipment—transformer vaults, rooftop gear, utility poles, inside water towers with lighting equipment, you name it. The Code doesn't want you climbing a rusty death trap to get to that panel 20 feet up.
Think about where these ladders live: outside in the rain, in damp transformer vaults, on the side of humid electrical rooms, in industrial plants where chemicals float around like rumors at a union meeting. If that ladder's made of plain carbon steel, it's gonna look like Swiss cheese in five years. Then some poor soul (probably you) is gonna put their boot through a rung while carrying a toolbelt and a bucket of fittings.
Corrosion resistant means we're talking:
- Hot-dipped galvanized steel
- Stainless steel (if you've got a Scrooge McDuck budget)
- Aluminum (check your local amendments—some places get picky)
- Fiberglass (great around electrical equipment anyway)
- Any factory-applied corrosion protection that meets manufacturer specs
What it does NOT mean is taking your buddy's old steel ladder, hitting it with a rattle-can of Rustoleum, and calling it "corrosion resistant." I've seen it. Don't be that guy.
Key Takeaways (The Stuff You Better Remember)
⚡ Fixed ladders must be corrosion resistant (not just "painted" or "looks okay for now")
⚡ This applies to ladders that provide access to electrical equipment (that's why it's in the NEC)
⚡ "Corrosion resistant" means the material itself or factory-applied protection—not field-applied paint jobs
⚡ This is about worker safety AND long-term reliability—Code doesn't want OSHA writing you up in five years when that ladder dissolves
⚡ Consider the environment: Coastal/marine = go stainless or heavy galvanizing; Indoor dry = regular galvanized is probably fine; Chemical plants = read the engineering specs twice
Real-World Jobsite Scenarios (Tales from the Trenches)
Scenario 1: The Rooftop Regret
You're running a service upgrade on a commercial building. Part of the job includes installing a fixed ladder up the outside wall to access the rooftop disconnect and HVAC electrical. Your supply house has a sweet deal on a regular steel ladder—$300 cheaper than galvanized.
Your foreman (who's been around since apprentices wore onions on their belts) says, "Kid, we're three miles from the ocean. That salt air will eat that thing alive. Spring for the galvanized or aluminum, bill it properly, and sleep well knowing you won't get a callback in three years."
He's right. Plus, when the building inspector shows up and sees that rusty ladder, guess who's replacing it on your dime? Not the supply house.
Scenario 2: The Transformer Vault Time Bomb
Industrial job. You're installing a fixed ladder into a below-grade transformer vault. It's damp down there—always is. The mechanical contractor installed a plain steel ladder last month (not your scope, not your problem, right?).
Wrong. The electrical inspector makes YOU fix it because it provides access to electrical equipment, which makes it part of the electrical installation per 110.79. Now you're cutting out someone else's work, eating the labor, and explaining to the GC why there's a change order. Meanwhile, the mechanical guy is at lunch.
Lesson learned: If you see someone installing the wrong ladder on your job, speak up BEFORE the inspector does. A five-minute conversation beats a two-day fix.
Scenario 3: The Water Tower Wakeup Call
You're bidding a job to install lighting and controls inside a municipal water tower. Site visit reveals the existing 40-foot fixed ladder is more rust than metal—looks like it's held together by paint and prayers.
Here's the deal: Even though you're only bidding the electrical, that ladder is how you ACCESS the electrical work. Include ladder replacement in your scope (galvanized or fiberglass) or put it in your exclusions list IN WRITING. Otherwise, when the inspector red-tags the whole job because of that ladder, guess who the owner's calling?
You. That's who.
What to Study (For When You're Taking That Test)
Examiners LOVE this one because it's simple but catches people off-guard:
📚 Know the requirement verbatim: "Fixed ladders shall be corrosion resistant" (seven words—you can memorize seven words)
📚 Understand what "fixed ladder" means: Permanent installation, not portable (if it's got wheels or you can carry it to your truck, it's not fixed)
📚 Know examples of corrosion-resistant materials: Galvanized steel, stainless steel, aluminum, fiberglass (they love asking "which of the following is acceptable")
📚 Understand the "why": Worker safety and access to electrical equipment (might show up as "What's the purpose of 110.79?")
📚 Common wrong answers they'll throw at you:
- "Painted steel is acceptable" (NOPE—paint is maintenance, not corrosion resistance)
- "Only required in outdoor locations" (NOPE—damp indoor locations need it too)
- "Only applies to ladders over 20 feet" (NOPE—ALL fixed ladders)
Exam Tip: If you see a question asking about ladders and electrical equipment access, and one answer says "corrosion resistant," that's probably your winner. This section doesn't mess around with exceptions or conditions—it's black and white.
Bottom Line: This rule is three things: Simple, important, and constantly ignored by people who aren't electricians. Don't be the one stuck replacing a rusty ladder because someone cheaped out. Spec it right, install it right, and you'll never think about it again—which is exactly how electrical installations should work.
Now get back to work. And for God's sake, check that ladder before you climb it. I don't care whose job it was to install it—your safety is YOUR responsibility.
Stay safe, stay Code-compliant, and remember: The cheapest bid isn't cheap if you're doing it twice.