110.15 - High-Leg Marking: The "Orange Wire of Death" Rule

The Straight Talk

Alright, listen up. You know that bastard high-leg in a 4-wire delta system? The one that'll bite you in the ass if you treat it like its brothers? Yeah, THAT one. This section says you need to mark that spicy 208V-to-ground leg ORANGE at every single spot where someone might hook something up—especially if the neutral is hanging around nearby looking all innocent.

Think of it like marking the one burner on the stove that's always hotter than hell. You want everyone to know: "Hey dummy, don't plug your 120V coffee maker into THIS one!"

The high-leg (sometimes called the "wild leg" or "stinger leg") measures about 208 volts to ground while its two buddies only measure 120V to ground. Connect a 120V load to the high-leg by mistake? Congratulations, you just made expensive smoke and possibly melted someone's equipment. The orange marking is your "here be dragons" warning label.

The rule is simple: If you've got a 4-wire delta system with a center-tapped transformer (giving you 120/240V delta with that weird 208V stepchild), you MUST mark that high-leg orange. Not yellow. Not red. ORANGE. Like a traffic cone screaming "WATCH YOUR ASS!"

Key Takeaways

The Technical Meat & Potatoes:

System type: Only applies to 4-wire, delta-connected systems with a grounded midpoint (typically 120/240V high-leg delta)
What to mark: The conductor or busbar with the higher voltage to ground (approximately 208V to ground vs. 120V on the other two phases)
Color required: ORANGE outer finish—no substitutions, no "close enough"
Where to mark: At EVERY point where a connection is made AND the grounded (neutral) conductor is present
How permanent: "Durably and permanently"—no tape that'll fall off in three months
Visibility requirement: Orange must be visible at all splices and terminations
Why it matters: Prevents 120V loads from being connected to 208V, which results in magic smoke, angry customers, and callback hell

Real-World Scenarios (Tales from the Trenches)

Scenario 1: The HVAC Guy's Expensive Lesson

You're working in an old manufacturing building with 120/240V high-leg delta service. The HVAC contractor shows up to replace the break room AC unit. He sees three phases and a neutral at the disconnect, assumes it's a normal 120/208V wye system, and hooks his 120V control transformer between what he THINKS is a phase and neutral.

Plot twist: He grabbed the high-leg (which some genius before him never marked orange). The transformer sees 208V instead of 120V, immediately cooks itself, and releases that special electrical burning smell we all know and love.

Why the orange marking matters: One glance at that orange conductor and he would've known to keep his 120V circuits the hell away from it. Instead, he's out $400 for a new transformer and his boss is chewing his ass.

Scenario 2: The "It Was Already Like That" Defense

You're troubleshooting an old panel in a strip mall. Nothing's marked. You need to add a circuit for a new sign. You throw your meter on what looks like a normal panel and—WHOA—one leg reads 208V to ground. Mystery solved: it's high-leg delta, and nobody bothered to mark it orange when they installed it 30 years ago.

Now YOU'RE the electrician of record for this job. If you don't mark that high-leg orange NOW and someone downstream gets hurt or fries equipment? Guess whose license is on the line? Yours, buddy.

The takeaway: When you find unmarked high-legs (and you will), fix that shit immediately. Hit it with orange phase tape at minimum, but do it right with heat shrink or permanent markers on the insulation. Cover your ass AND the next guy's.

Scenario 3: The Apprentice and the Vending Machine

Your greenie is running power to a new vending machine. It's got a 120V plug. He sees the 4-wire panel, spots a neutral, and thinks "Piece of cake—just need a hot and a neutral."

You catch him reaching for the unmarked conductor. "STOP! Check that leg to ground first!"

Sure enough: 208V. That vending machine would've lasted about 15 seconds before its control board became a charcoal briquette.

Why it matters: That orange marking is literally idiot-proofing. Not because your apprentice is an idiot—he's green. The orange screams "DANGER: NOT NORMAL!" loud enough that even tired electricians at 4 PM on Friday will notice.

What to Study (Exam Gold)

If you're studying for your Journeyman or Master's exam, here's what they LOVE to ask about 110.15:

1. The Color (They love this one):

Q: "What color must the high-leg be marked?"
A: ORANGE. Not yellow, not red-orange, not "rusty orange-ish." ORANGE.

2. The System Type:

They'll give you various system configurations. Know that this ONLY applies to 4-wire delta systems with a center-tapped (grounded midpoint) transformer
3-phase wye systems? Doesn't apply (all legs read 120V to ground in typical 120/208V wye)
3-wire delta? Doesn't apply (no neutral = no confusion)

3. Where to Mark:

"At each point on the system where a connection is made IF the grounded conductor is also present"
They'll try to trick you: "Must it be marked inside a 3-phase motor starter with no neutral?" Answer: NO—neutral isn't present
"Must it be marked in a panel with both phases and a neutral?" Answer: HELL YES

4. The "Why" Question:

Be ready to explain WHY we mark it: The high-leg has approximately 208V to ground (specifically, 1.732 × 120V = 208V) while the other two legs have 120V to ground
This is due to the geometry of the delta configuration with the center tap

5. Acceptable Marking Methods:

"Outer finish" (colored wire insulation)
Orange tape at terminations and splices
Orange paint on busbars
Heat shrink tubing
Key phrase: whatever you use, it must be "durable and permanent" AND "visible at all splices and terminations"

Exam Trap Alert: They might show you a picture of a panel schedule or diagram and ask you to identify which leg should be marked orange. Remember: it's the leg connected to the phase winding that's NOT center-tapped. Usually shown as phase B in diagrams.

The Bottom Line

Look, high-leg delta systems are getting rarer, but they're still out there—especially in older commercial and industrial buildings. When you encounter one, marking that high-leg orange isn't just code compliance theater. It's genuinely preventing equipment damage and keeping people safe.

Think of it this way: That orange marking costs you maybe 30 seconds and $2 worth of tape. NOT marking it can cost thousands in fried equipment, a callback, a pissed-off customer, and possibly your license if someone gets hurt.

And when you're taking your exam? Just remember: "High-leg = High voltage to ground = Orange, everywhere you might make a connection where the neutral is also around to confuse you."

Now get out there and mark those spicy legs orange before some poor bastard learns the hard way!