110.22 - Identification of Disconnecting Means

Or: "Label Your Damn Switches (Because Future You Will Thank Past You)"

The Plain-Language Breakdown

Listen up. You know that feeling when you're troubleshooting a panel at 2 AM, the service manager is blowing up your phone, and every breaker is labeled "STUFF" or not labeled at all? Yeah, this section exists because some clown keeps making our lives harder.

(A) General - The "No Mystery Switches" Rule

Every disconnect needs a legible label telling anyone what it does. Period. End of story.

Now, if it's painfully obvious what the disconnect controls—like it's literally mounted on the equipment three inches away—you might get a pass. But here's the thing: what's obvious to you at noon on installation day won't be obvious to the poor bastard troubleshooting it at midnight six years from now. That poor bastard might be YOU.

Here's where it gets spicy: In anything bigger than a house or duplex (commercial, industrial, apartment buildings, etc.), your label game needs to level up. You can't just write "HVAC Unit" anymore. Nope. Now you need to include:

• WHAT it controls (the load)
• WHERE the power comes from (which panel, which breaker)

So instead of "Compressor," you need something like "Compressor 2 - Fed from Panel 3B, Breaker 15."

Why? Because when the sous chef at that restaurant electrocutes himself on equipment fed from a mystery panel, guess whose license is on the line? Hint: it ain't the cook's.

And one more thing: That label needs to survive its environment. A Sharpie on painter's tape doesn't count, hotshot. We're in the industrial freezer? Get a proper label. Outside in the Arizona sun? Better be UV-resistant. Caustic chemical plant? You get the idea.

(B) Engineered Series Combination Systems - The "Engineer Says Don't Touch" Label

Okay, this one's for the big-brain projects where an engineer gets involved with series ratings per 240.86(A).

Quick refresher on series ratings: Sometimes you can use a smaller (cheaper) breaker downstream if it's backed up by a beefier breaker upstream. The combo together can handle the available fault current even though the little guy alone couldn't. It's like having a bantamweight boxer backed up by Mike Tyson—works great as long as they stay together.

When an engineer designs this setup, you need a field-applied label that screams:

"CAUTION — ENGINEERED SERIES COMBINATION SYSTEM RATED _____ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED."

Fill in the blank with the actual rating. And here's the critical part: IDENTIFIED REPLACEMENT COMPONENTS REQUIRED means you can't just throw any old breaker in there when one fails. You need the EXACT component the engineer specified, or the whole house of cards falls apart (possibly literally, in a shower of arc flash).

This label needs to meet the requirements in 110.21(B), meaning it's gotta be permanent, legible, and able to survive. No label-maker specials that peel off in six months.

(C) Tested Series Combination Systems - The "Factory Says Don't Touch" Label

This is the same deal as (B), except the manufacturer did the testing and marked the series combination on the equipment (per 240.86(B)). You're just buying it off the shelf already tested and approved.

You still need a field label, but it's slightly different:

"CAUTION — SERIES COMBINATION SYSTEM RATED _____ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED."

Notice the difference? "SERIES COMBINATION SYSTEM" instead of "ENGINEERED SERIES COMBINATION SYSTEM." One word difference, but it tells you who did the homework—the manufacturer vs. an engineer.

Again, when a breaker fails, you can't just grab whatever's on the truck. You need the exact replacement component or you've just voided the rating and possibly turned the panel into a potential bomb.

Key Takeaways (The Stuff That Matters)

1. Every disconnect needs a legible, durable label indicating its purpose (unless it's brain-dead obvious what it controls)

2. Commercial/Multi-family requirements are stricter: Labels must include BOTH the load AND the source (panel and breaker location) feeding the disconnect

3. Labels must survive their environment: No cheap solutions—plan for sun, rain, chemicals, temperature extremes

4. Series-rated systems need special caution labels:

   • Engineered systems: "CAUTION — ENGINEERED SERIES COMBINATION SYSTEM RATED ___ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED."
   • Tested systems: "CAUTION — SERIES COMBINATION SYSTEM RATED ___ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED."

5. "IDENTIFIED REPLACEMENT COMPONENTS REQUIRED" is not a suggestion—it means specific, approved parts ONLY

6. Series rating labels must meet 110.21(B) requirements: permanent, legible, and readily visible

Real-World Scenarios (Why This Sh*t Matters)

Scenario 1: The Friday Afternoon Fire Drill

You're doing service work in a 200,000 sq ft warehouse. Machine goes down. Foreman is losing his mind because production stopped. You find the disconnect on the machine, but there's no label. The wire disappears into the ceiling and goes... somewhere.

You spend the next 45 minutes playing "follow the conduit" through a jungle of cable tray, finally tracing it back to Subpanel D-7 on the mezzanine, breaker 23. What should've been a 10-minute fix is now an hour-long treasure hunt. The foreman is no longer speaking to you, and your boss is getting an earful.

If the original installer had just labeled it: "Press #4 - Fed from Panel D-7 Breaker 23." You'd have been a hero instead of the guy who cost them an hour of production.

Scenario 2: The Series Rating Surprise

Maintenance guy at a manufacturing plant has a breaker that keeps tripping on a production line. He's got a spare 100-amp breaker on the shelf (non-identified, just something they stock), so he swaps it in. Problem solved, right?

Wrong. That panelboard was series-rated with specific components. The new breaker looks the same but has a different interrupt rating. Three weeks later, there's a ground fault, massive fault current flows, and the new breaker can't handle it. Arc flash. Explosion. Equipment destroyed. Maintenance guy in the hospital. Company bankrupted by lawsuits.

If the panel had been properly labeled with the series rating warning and "IDENTIFIED REPLACEMENT COMPONENTS REQUIRED," maybe—just maybe—that maintenance guy would've called an electrician who knew better.

Scenario 3: The Inspector's Revenge

You finish a beautiful tenant improvement in a strip mall. Twenty new disconnects for all the restaurant equipment. You labeled every single one: "Fryer 1," "Fryer 2," "Hood Fan," "Walk-in Cooler." You're feeling proud.

Inspector shows up, takes one look, and red-tags the whole job. Why? It's commercial. You needed to include the SOURCE for each disconnect. "Fryer 1 - Panel K2, Breaker 7." That's what he wanted.

Now you're back on site with your label maker, doing the walk of shame, while the GC screams about schedule delays. All because you skipped three words per label.

What to Study (For the Test)

If you're prepping for your Journeyman or Master's exam, here's what they LOVE to ask about:

High-Probability Test Questions:

1. What's required on disconnect labels in commercial buildings that ISN'T required in residential?

   • Answer: Location and identification of the SOURCE (panel and breaker)

2. What are the two types of series combination systems, and how are their labels different?

   • Engineered (designed by engineer) vs. Tested (manufacturer-tested)
   • Labels differ by one word: "ENGINEERED" vs. regular

3. What does "IDENTIFIED REPLACEMENT COMPONENTS REQUIRED" mean?

   • Only use the specific components approved for that series rating—no substitutions

4. When can you skip labeling a disconnect?

   • When the purpose is "evident" based on location and arrangement (but good luck convincing an inspector of that)

5. What section covers the durability requirements for permanent labels?

   • 110.21(B)—know this cross-reference

6. What's the minimum information required on a series combination system label?

   • "CAUTION," type of system, ampere rating, and warning about identified replacement components

Study Tips:

• Memorize the exact wording of those caution labels—tests love fill-in-the-blank questions
• Understand the difference between 240.86(A) and 240.86(B)—engineered vs. tested series ratings
• Know that commercial/multi-family = stricter labeling (source info required)
• Remember: durability matters—the label must withstand the environment

The Bottom Line

This section is about respecting the next person who touches your work. Maybe it's another electrician. Maybe it's a maintenance worker. Maybe it's you in five years when you've forgotten everything about this job.

Good labeling is cheap, fast, and the mark of a professional who gives a damn. Bad labeling (or no labeling) is expensive, dangerous, and the mark of a hack.

And those series rating labels? They're not just CYA paperwork—they're literally preventing explosions. Take them seriously.

Now get your label maker charged up and do it right the first time. Your future self will buy you a beer.