NEC 110.25: Lockable Disconnecting Means
Or: "No, Kevin, Your Zip-Tie Through the Handle Doesn't Count"
THE STRAIGHT TALK
Alright, listen up. You know that disconnect switch you're standing in front of? If the Code says it needs to be "lockable open" somewhere—anywhere—in the NEC, here's what that actually means:
It needs to accept a lock in the OFF position. Period.
But here's the kicker that trips everybody up: The little tab, hole, or hasp that accepts the lock? That sucker has to stay attached to the equipment whether you've got a lock on it or not.
Yeah, I'm talking to you, sparky—the guy who thought those removable lockout tabs were genius because "we only need 'em during maintenance." Wrong. Those have to be permanently installed. The lock can come and go, but the means to lock it stays put.
EXCEPTION: The only time you get a pass is with cord-and-plug connections. Yeah, you can unplug your tablesaw and take the lockout device with you. The Code writers aren't completely insane.
(This section applies to systems 1000V AC or less, and 1500V DC or less—you know, the stuff that'll only mostly kill you.)
KEY TAKEAWAYS (The Stuff That Matters)
🔒 Lockable means LOCKABLE: If any Code section requires a disconnect to be "lockable open," it must physically accept a lock when in the open (OFF) position.
🔧 The lockout provisions are PERMANENT: The hasp, tab, hole, or whatever gizmo lets you slap a lock on there stays installed—lock or no lock. You can't use those wimpy removable deals that fall off when you're not actively locking it out.
🔌 Cord-and-plug exception: Cord-connected equipment gets a break. The lockout provisions don't have to be permanent for these—because, duh, you're unplugging the whole thing anyway.
⚡ Voltage limits: This section covers your everyday electrical systems: up to 1000V AC or 1500V DC. (Over that? You're playing with the big boy rules in other articles.)
REAL-WORLD JOBSITE SCENARIOS
Scenario 1: The Great Fusible Disconnect Debate
You're installing a new 200A fusible disconnect for an RTU on a commercial roof. Your foreman hands you a disconnect with one of those snap-out knockouts that accepts a padlock—but only when you punch the little tab out.
"Perfect!" you think. "We'll punch it out when we need to lock it."
BZZZT. Wrong.
Inspector shows up, takes one look, and says, "That lockout provision needs to be in place whether it's locked or not. Punch that tab now or swap the disconnect."
Why? Because 110.25 says the provisions for locking stay in place. That removable tab is only Code-compliant after you make it permanent. Punch it, file the edges, move on with your life.
Scenario 2: The Maintenance Bay Blues
You're wiring a maintenance shop with twenty circuits feeding different equipment. Every single receptacle circuit needs a lockable disconnect per company spec (and honestly, good safety practice).
You price out twenty disconnects with built-in hasps. Your boss nearly has a stroke at the quote.
"Can't we just use cheap disconnects and add padlock hasps later if we need them?"
Nope. If the installation requires lockable disconnects (whether by Code reference or your spec), those lockout provisions must be there from day one—even if nobody's locking anything yet.
You can scrimp on the lock itself. You cannot scrimp on having a place to put it.
Scenario 3: The Cord-and-Plug Save
Your apprentice is installing a lockout on a 240V compressor. It's hardwired into a disconnect, and he's wrestling with some janky aftermarket hasp kit that keeps falling off.
You walk over: "Dude, what're you doing?"
"Trying to make this lockable!"
You look at the compressor. It's got a 50A plug and receptacle, three feet of cord.
"Just lock out the plug, genius. Write 'LOCKED OUT' on a tag, wrap it around the male end, and put that in the lockbox."
Why it works: Cord-and-plug connections are the only time you get to use temporary lockout provisions. Unplug it, lock up the plug, you're golden. That's your exception in action.
WHAT TO STUDY (For Licensing Exams)
If you're staring down a Journeyman or Master exam, here's what they love to ask about 110.25:
High-Probability Test Questions:
-
"What does 'lockable open' mean?"
Answer: Capable of being locked in the open (OFF) position AND the lockout provisions remain in place with or without the lock. -
"Can you use a disconnect with removable lockout tabs?"
Answer: Only if you make them permanent (i.e., punch them out and leave them). They can't be the type you take completely off when not locked out. -
"What's the exception to permanent lockout provisions?"
Answer: Cord-and-plug connections. The lockout provisions don't have to stay in place for these. -
"Does 110.25 apply to systems over 1000V AC?"
Trick question: This section (Part II) specifically covers systems UP TO 1000V AC / 1500V DC. Different rules for higher voltages.
Code Reference Shortcuts:
- 110.25 - The main lockout rule (know it cold)
- Look for "lockable" anywhere else in the Code—this section defines what that means
- Cross-reference with 110.3(B) (Installation and Use) for listed equipment requirements
Exam Traps to Avoid:
❌ Thinking you can install lockout provisions "later when needed"
❌ Assuming cord-and-plug stuff needs permanent hasps
❌ Confusing "lockable" with "accessible" (totally different requirements)
THE BOTTOM LINE
The NEC wants you to be able to lock stuff out right now, not after you scramble to find the little baggie of parts that came with the disconnect five years ago. The lockout hardware is permanent. The lock itself? That can be as temporary as your apprentice's attention span.
Your disconnects need to be ready to accept a lock today, whether you're locking them today or not.
And for crying out loud, stop trying to get creative with zip-ties, wire, and duct tape. There's already enough sketchy stuff on jobsites without making up new methods.
Remember: Locks are optional. The ability to install one isn't.
Now go forth and install some proper lockout-ready disconnects. Your future self (and the inspector) will thank you.