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Building Code Reference

Got a CEC 110.14 correction?

Conductor termination ratings

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

CEC 110.14 is the California Electrical Code section that governs conductor termination temperature ratings and torque requirements. Every terminal on a breaker, lug, or bus bar carries a listed temperature rating (typically 60°C or 75°C) and a torque value in inch-pounds. When wire is landed on a termination that does not match the conductor’s ampacity column, the connection runs hotter than the equipment was designed to handle. Plan inspectors flag this section on residential panel upgrades, service changes, and feeder runs where conductor sizing and equipment listings do not align.

How to fix it

  1. Identify the terminal temperature rating from the equipment listing

    Pull the panel or equipment data sheet and find the terminal temperature rating before you do anything else. Residential panels and most commercial gear list terminals at 75°C. Some older residential equipment rates terminals at 60°C. The rating appears on the data sheet or on the product label inside the panel door. Write that temperature rating on the cover sheet of your electrical plans so the plan-checker can verify it without hunting for the data sheet themselves. If the panel has multiple terminal sizes with different ratings, note each one separately.

  2. Re-check conductor ampacity against the correct temperature column

    Once you have the terminal rating confirmed, open Table 310.16 and re-verify each conductor against the correct column. If terminals are listed at 75°C, use only the 75°C ampacity column, not the 90°C column, even if the conductor is THHN rated 90°C. For a 20A circuit with 12 AWG THHN, the 75°C column gives 25A, and the 240.4(D) small-conductor rule caps the breaker at 20A, which works. For a 100A feeder, the 75°C column for 4 AWG copper gives 85A, which is short, so you would need 3 AWG to reach 100A. Update any conductor sizes on the plans that were originally pulled from the wrong temperature column.

  3. Confirm each termination point is listed for the number of conductors

    Check every lug and terminal block called out on the plans. If you are running parallel feeders or combining conductors at a junction, verify the lug is listed for multiple conductors. The equipment listing or data sheet will say single conductor only or provide a range of conductor counts allowed. If a lug is single-conductor only and the design requires two conductors at that point, spec a parallel lug kit that is UL-listed for that configuration. Note the listing reference on the plans.

  4. Add specific torque values to the electrical plan notes

    Add a note block on your electrical plans that references the specific torque values from the equipment listing. For example: Terminate 6 AWG and smaller at 25 in-lb per the panel installation guide; 4 AWG and larger at 35 in-lb per the same listing. A generic torque per manufacturer note is not enough. Plan-checkers want to see that the listed torque value is documented on the permitted plans, not just buried in a manual the field inspector may never have. If you cannot locate a torque value in the data sheet, check the installation manual that ships with the panel or contact the manufacturer directly.

  5. Update load calculations to reflect any corrected conductor sizes

    If you changed any conductor sizes in Step 2, rerun the load calculation sheet. Every feeder, subpanel, and service calculation that referenced the old wire size needs to be updated. Submit the revised load calculations with the resubmittal. Plan-checkers will compare them against the revised panel schedule and one-line diagram to confirm the numbers match. A mismatch between the load calc and the panel schedule is one of the fastest ways to trigger a follow-up correction on the same project.

  6. Document any panel substitutions with updated terminal ratings

    If the panel brand or model changed after the original permit submittal, include the new data sheet in the resubmittal package and explicitly call out the terminal temperature rating of the replacement equipment. Include a brief note confirming the conductors are still correctly sized for the new terminal ratings. Swapping a panel without this documentation is a consistent source of second and third corrections on the same project, because the plan-checker has no way to verify the sizing without it.

  7. Check HVAC and appliance terminal ratings separately

    HVAC equipment, water heaters, and similar appliances often have 60°C-rated terminals even when the supply circuit uses 75°C-rated THHN. Check the appliance nameplate and the installation instructions for the terminal rating. If the appliance terminal is 60°C, size that circuit’s conductors using the 60°C ampacity column, regardless of what the panel terminals allow. Note this on the equipment connection detail in the electrical plans and reference the appliance manufacturer’s terminal rating. This is a common miss on ADU projects where mini-split systems are added on a new circuit.

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Why you got flagged

Plan-checkers flag CEC 110.14 corrections for a handful of specific reasons that come up repeatedly on residential and light commercial work.

The most common scenario is calculating ampacity at the 90°C column when the termination equipment is only listed for 75°C. THHN conductor is rated 90°C, which makes it tempting to use the full 90°C ampacity from Table 310.15(B)(16). But if the breaker lugs, panel bus terminals, or load-side device are listed at 75°C, which is typical for most residential equipment, you have to use the 75°C column for sizing. The plan-checker will catch it when your load calculations do not match the terminal’s listed rating.

The second trigger is missing or unspecified torque callouts on the electrical plans. Most panels now require a torque wrench on terminal connections, and the equipment listing specifies the exact inch-pound value for each conductor size. Plans that say torque connections per manufacturer without the specific listed value often draw a correction because the inspector cannot verify it in the field.

A third cause is landing multiple conductors under a lug that is listed for a single conductor only. Some lugs are UL-listed for one conductor, and adding a second wire under the same lug violates 110.14(A) regardless of torque. If your feeder design implies parallel conductors at a shared termination point, expect a flag unless the lug is explicitly listed for that configuration.

Panel substitutions mid-project introduce a fourth risk. If the replacement panel has 60°C-rated terminals and the original conductor sizing assumed 75°C, the ampacity does not match the new listing and the entire feeder sizing needs to be recalculated before resubmittal. This is one of the situations where a single swap creates three or four downstream corrections.

The official code

California Building Standards Code, Title 24 Part 3 — California Electrical Code

Read the source →

Common questions

Can I use 90°C conductor ampacity if the breaker is only rated for 75°C?
No. CEC 110.14(C) requires you to use the lower of the conductor’s temperature rating or the termination’s temperature rating when determining ampacity. If the breaker terminal is listed for 75°C, you must size the conductor using the 75°C ampacity column in Table 310.15(B)(16), even when the wire itself is 90°C-rated THHN. The 90°C column is only available when both the conductor and every termination in the circuit are listed for 90°C, which is uncommon in residential and standard light commercial panels. Using the 90°C column when the lugs are 75°C is the single most common reason this section shows up on a corrections letter.
Does CEC 110.14 apply to low-voltage and control wiring?
The torque and temperature-rating requirements under 110.14 apply to all electrical wiring covered by the CEC. For Class 2 and Class 3 low-voltage circuits that fall under CEC Article 725, typically below 50V, the physical termination requirements are governed by the device listing rather than 110.14 directly. But for any circuit that falls under CEC general wiring methods, including control circuits for HVAC units, fire alarm power supplies, and motor controls, 110.14 applies. When in doubt, check the equipment listing for the terminal rating and follow that listing.
What torque value do I use if the data sheet does not list one?
Check the installation manual that ships with the panel or device. Most panel manufacturers publish torque tables broken down by conductor size in the installation guide, even when the data sheet does not include them. If you still cannot locate a value, contact the manufacturer’s technical support directly and get the specification in writing, then include that documentation in your permit package. In practice, the major residential panel manufacturers such as Square D, Eaton, Siemens, and Leviton publish torque tables in their installation guides and on their technical support portals. A missing torque value is a solvable problem, not a reason to write a generic per-manufacturer note.
Does CEC 110.14 apply to ADU subpanel feeders?
Yes. ADU subpanel feeders are subject to the same termination temperature and torque requirements under CEC 110.14. The feeder conductors must be sized to the lower of the terminal rating at the main panel and the terminal rating at the ADU subpanel. Both the main breaker feeding the ADU and the subpanel’s main lugs must be considered. ADU electrical plans frequently draw corrections here because the feeder is sized using 90°C ampacity when one of the two termination points is 75°C-listed. Check both ends before you finalize the conductor size on the plan.
Can I use aluminum conductors and still meet 110.14 termination requirements?
Aluminum conductors are allowed, but you need to confirm two things. First, check that the terminal is listed for aluminum use. Many panel lugs are listed for copper only. If the panel listing says CU only, aluminum conductors are not permitted at that terminal regardless of temperature rating. Second, if the terminal accepts aluminum, size the conductor using the 75°C aluminum column in Table 310.15(B)(16), which typically means going up one conductor size relative to copper. Use CO/ALR-rated connectors where required by the listing and note the connector rating on the plans.
What is the difference between CEC 110.14(A) and 110.14(C)?
Section 110.14(A) covers the physical construction of the termination. The lug, connector, or device must be listed and installed per its listing, which includes how many conductors are allowed under it and what torque value to apply. Section 110.14(C) is the temperature-rating rule: conductors must be sized using the temperature column that matches the lowest-rated termination in the circuit. Most plan-check corrections cite 110.14 broadly, but the specific fix depends on which part applies. Wrong torque or two conductors under a single-conductor lug is a 110.14(A) issue. Ampacity calculated against the wrong temperature column is a 110.14(C) issue. Knowing which one you are fixing makes the correction response cleaner and faster.

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