110.14 - ELECTRICAL CONNECTIONS: Don't Be That Guy Who Burned Down the Strip Mall

The Straight Talk Version

Look, I know you're thinking "here we go, another boring section about connections." But hold up—this is literally the most important thing you'll do all day. You can have the prettiest conduit bends in three counties, but if your connections suck, you're gonna have problems. Bad connections are like bad relationships: they get hot, they spark, and eventually something burns down.

The Golden Rule: Match Your Stuff

Here's the deal: everything at a connection point needs to play nice together. You can't just jam copper and aluminum together like they're old buddies at a tailgate party. They're not. They're mortal enemies that will corrode and cause fires when you mix them without the right connector.

Think of it this way: your termination is only as good as its weakest link. Got a 90°C conductor? Awesome. But if you're landing it on a 60°C terminal, you're using 60°C ampacity. Period. That 90°C insulation just became expensive jacket material.

The Device Gotta Match the Wire

Your pressure connectors, lugs, and splicing devices need to be identified (that's code-speak for "it better say so on the device") for the conductor material you're using. Copper lugs on copper. AL-rated stuff on aluminum. Don't get creative here—this isn't Iron Chef.

And if you're working with those fancy fine-stranded conductors (anything more flexible than standard Class B or C stranding), you need connectors specifically rated for that class. Regular lugs will cut through fine strands like a hot knife through butter, and then you'll wonder why your VFD keeps tripping.

Terminals: The Landing Zone

Here's your options for landing conductors:

• Pressure connectors (including those set-screw types that every apprentice over-tightens)
• Solder lugs (properly applied, not that cold-solder garbage)
• Splices to flexible leads
• Wire-binding screws or studs with nuts - but ONLY for #10 AWG and smaller

If you're landing more than one conductor under a single terminal, that terminal better be identified for multiple wires. Same goes for aluminum—if the terminal isn't marked for AL, don't even think about it. I don't care if your helper says "we do it all the time." We also used to use asbestos, and that didn't work out so great.

Splices: Marriage, Not a One-Night Stand

When you splice conductors, you've got options:

• Listed splicing devices (your wire nuts, Polaris connectors, etc.)
• Brazing, welding, or soldering

CRITICAL: If you're soldering, the connection needs to be mechanically and electrically secure BEFORE you even break out the solder. The solder is the icing, not the cake. If you're relying on solder for mechanical strength, you've already lost.

And here's the kicker: every splice and every conductor end needs insulation equal to what was on the conductor originally. No "I'll just tape it up good" nonsense. We're professionals, not shade-tree mechanics.

Special note for you underground guys: Direct burial splices require listed devices specifically for burial. That regular wire nut in a Ziploc bag? Nope. I've seen it. Don't be that guy.

Temperature Ratings: The Math That Actually Matters

Alright, put down your phone for this part because this trips up even veteran sparkies.

The Rule: You use the LOWEST temperature rating of anything in the circuit—conductor, terminal, or device. Always.

For circuits 100A or less (or marked for #14-#1 AWG):

• Default to 60°C ampacity unless the equipment specifically says otherwise
• Got THHN (90°C) wire? Cool story. You're still using the 60°C column from Table 310.16
• Exception: Motors with design letters B, C, or D get to use 75°C ratings

For circuits over 100A (or larger than #1 AWG):

• Default to 75°C ampacity
• Same deal—90°C wire gets treated like 75°C for terminations

Now here's the beautiful part: You CAN use the higher temperature rating of your conductor for derating purposes (adjustment and correction factors), you just can't exceed the terminal rating at the end.

Example from the real world: You're running a 40A circuit in a hot attic. You start with #8 THHN (90°C rated):

• Check Table 310.16: #8 at 90°C = 55A
• Apply your correction factor for the hot attic: let's say it's 0.80
• 55A × 0.80 = 44A (you're good!)
• But when you land it on your 60°C terminal, you check that #8 at 60°C = 40A
• Perfect fit!

If you had used 60°C wire from the start, you'd have needed #6 to handle the derating, even though you only need 40A at the terminal.

Torque: Tighten It Right or Go Home

This is new-ish territory where the Code actually caught up with what smart electricians have been doing for years. If the manufacturer gives you a torque spec (and they will), you SHALL hit that number. Not "kinda close." Not "I've been doing this for 20 years, I know what tight feels like." The actual number.

Get yourself:

• A torque screwdriver
• A torque wrench for the big stuff
• Or use those fancy breakaway bolts that snap at the right torque

"But boss, I don't have a torque wrench!"

Then get one. They're cheaper than the service call when your loose connection burns up, and WAY cheaper than the lawsuit. Check UL 486A-486B if you can't find the manufacturer's specs, or call them. They'll tell you.

KEY TAKEAWAYS (The Stuff That'll Save Your Bacon)

🔧 Connection Devices Must Be Identified:

• Use connectors and lugs rated for your conductor material (Cu, AL, Cu-clad AL)
• Fine-stranded conductors need connectors identified for that specific class
• Multi-conductor terminals must be marked for multiple wires

⚡ Terminal Temperature Rules:

• ≤100A circuits or #14-#1 AWG → 60°C default

• 100A circuits or larger than #1 AWG → 75°C default

• Motor circuits with design letters B, C, D → 75°C
• Use higher-temp wire ratings for derating calculations, but terminate at the lower rating

🔥 Conductor Mixing is a No-Go:

• Different conductor materials can't touch in a connector unless it's rated for that
• Dissimilar metals = galvanic corrosion = fire = unemployment

🔩 Splice Requirements:

• Must be mechanically secure BEFORE soldering
• Insulation must equal original conductor insulation
• Direct burial splices must be listed for burial

⚙️ Torque Specifications are Mandatory:

• Use manufacturer's torque values (required!)
• Use calibrated torque tools
• Check UL 486A-486B Annex I or NFPA 70B if manufacturer specs unavailable

REAL-WORLD SCENARIOS (Tales From the Trenches)

Scenario 1: The Aluminum Fiasco

Location: Commercial remodel, 200A feeder

Young buck electrician lands aluminum feeders on copper-only lugs in a panel because "they fit." Six months later, the connection corrodes, gets hot, and burns up half the panel during lunch rush. Health inspector shuts down the restaurant.

The lesson: That "AL9CU" rating stamp isn't a suggestion—it's your get-out-of-jail-free card. If it doesn't say AL, keep your aluminum away from it.

Scenario 2: The 90-Degree Disaster

Location: Big-box retail, 120A circuit

Electrician runs #1 THHN (90°C) for a 120A load. Checks Table 310.16 at 90°C: #1 = 150A. "I'm golden!" he thinks. Lands it on a breaker marked 75°C only. At 75°C, #1 is only good for 130A. Should've used #1/0.

Inspector tags it. Now they're pulling new wire because someone didn't read 110.14(C)(1)(b).

The lesson: The terminal rating always wins. Always check the lower temperature column for your final ampacity at terminations.

Scenario 3: The "I Don't Need No Torque Wrench" Guy

Location: Industrial facility, 400A feeder

Old-timer installs 400A breaker, hand-tightens the lugs "like I've done for 30 years." Connection starts running hot within weeks. Plant engineer catches it during a thermal scan before it causes a shutdown. Re-torquing solves the problem.

The lesson: Your hand isn't a calibrated tool. The Code requires torque specs for a reason. Spend $50 on a torque screwdriver or spend $5,000 on an emergency service call.

Scenario 4: The Buried Treasure

Location: Landscape lighting, underground splice

Handyman (not an electrician, of course) uses regular wire nuts in electrical tape for underground splices feeding yard lights. Fast-forward one year: water intrusion, corrosion, lights flickering like a horror movie. Now you're digging up the yard and replacing everything with proper direct-burial splicing devices.

The lesson: Listed for burial means LISTED FOR BURIAL. Not "wrapped real good."

Scenario 5: The Fine-Strand Face-Plant

Location: Control panel with VFD

Electrician lands fine-stranded Class K control wire (super flexible stuff) in a standard terminal block rated for Class B stranding. Over-tightens it "to make sure it's secure." The terminal block screw cuts through half the strands. Six months later, the connection fails during production.

The lesson: Match your connector to your conductor class. Fine-stranded wire needs fine-strand-rated connectors. Check Chapter 9, Table 10 to know what you're working with.

WHAT TO STUDY (AKA What's On The Test)

When you're studying for your journeyman or master's exam, the testing gods LOVE this section. Here's what they'll hit you with:

High-Probability Exam Topics:

1. Temperature rating questions (like, 40% of connection-related questions)

   • "A circuit rated 125A is terminated on equipment marked 75°C. What conductor temperature rating must be used?"
   • Know the 100A threshold cold: ≤100A = 60°C default, >100A = 75°C default

2. Aluminum termination requirements

   • "Can you land aluminum wire on a terminal marked 'Cu'?" (No, dummy)
   • They'll show you a terminal marking and ask if it's suitable for aluminum

3. Multi-wire terminal identification

   • Questions about landing two wires under one terminal
   • The terminal must be identified for multiple conductors

4. Splice requirements

   • "What must be done to a soldered splice before applying solder?"
   • Answer: Make it mechanically and electrically secure first

5. Torque requirements (this is trending up on newer exams)

   • "What document provides torque values if manufacturer specs aren't available?"
   • Answer: UL 486A-486B Annex I

6. Temperature calculation scenarios

   • They'll give you a wire size, ambient temp, and ask you to calculate if it's suitable
   • You'll need to use the higher temp rating for corrections, but the lower rating for terminals
   • Practice these! They're worth big points

Code References to Bookmark:

• Table 310.16 - Your temperature/ampacity lookup table (you'll use this constantly)
• Chapter 9, Table 10 - Conductor stranding classes
• 110.14(C)(1)(a) - The 100A and under rule (60°C default)
• 110.14(C)(1)(b) - The over 100A rule (75°C default)

Practice Problem Format:

They love to give you something like this:

"A continuous load of 45 amperes is supplied by a circuit in an ambient temperature of 50°C. The terminals are rated 75°C. Using THHN conductors and Table 310.16, what is the minimum size conductor required?"

How to solve it:

1. Continuous load = 45A × 1.25 = 56.25A
2. Check Table 310.16 correction factors: 50°C ambient = 0.75 correction factor
3. Required conductor ampacity before correction = 56.25A ÷ 0.75 = 75A
4. Look at 90°C column (THHN is 90°C): #4 THHN = 85A (works after correction)
5. But check terminal rating: #4 at 75°C = 85A ÷ 0.94 (correction) = 79A after adjustment
6. Still good! Answer: #4 THHN

THE BOTTOM LINE

Listen, I get it. Connections aren't glamorous. Nobody's taking Instagram photos of your wire nuts. But here's the truth: every fire investigation I've been part of, every callback I've done, every "why is this breaker hot?" call—probably 70% trace back to connection problems.

• Loose connections get hot
• Wrong temperature ratings cause overloads
• Dissimilar metals corrode
• Improper splices fail

This section isn't trying to make your life harder. It's trying to keep buildings from burning down and keep your license out of the shredder.

Do these things:

• Match your connectors to your conductors
• Use the correct temperature ratings (when in doubt, go lower)
• Torque everything to spec
• Don't mix metals without the right hardware
• Make mechanical connections before you solder

Don't be these guys:

• "Close enough" guy
• "I've never had a problem" guy
• "That torque spec is just a suggestion" guy
• "Aluminum, copper, they're both metal" guy

Your reputation rides on your connections. Make 'em right.

Now get back to work, and for the love of Mike Holt, buy a torque wrench.

Remember: The Code is minimum standards. Your grandmother's house, your kid's school, your buddy's shop—they're all counting on you to do it right. No pressure or anything. 😉