Terminal Temperature Rating Chart

Use this worksheet after ampacity or wire-size calculator results to record conductor temperature rating, derating starting basis, equipment terminal limit, and final capped ampacity.

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Quick reference table

Use this worksheet after the calculator result to make terminal temperature rating the cap check on conductor ampacity. A conductor insulation rating may support an adjustment calculation, but the final usable ampacity must still respect equipment terminal markings, manufacturer instructions, conductor material, and the adopted NEC/AHJ basis for the installation.

Terminal rating worksheet checkpoints

Terminal rating worksheet checkpoints
Checkpoint	Record from calculator or equipment	Verification note
Conductor insulation	60C, 75C, or 90C selection	Confirm marking on conductor or cable assembly
Adjustment basis	Temperature rating used for derating	Confirm it is allowed for the conductor and workflow
Equipment terminals	Selected or marked terminal limit	Confirm equipment marking, conductor material, and instructions
Torque and preparation	Manufacturer instruction reference	Record torque, conductor preparation, and connector requirements
Capped ampacity	Lower final usable ampacity	Carry this value into load and OCPD checks

Result review after terminal cap

Result review after terminal cap
Calculator output	What can still cap it	Document before final use
Adjusted ampacity higher than terminal limit	Equipment terminal rating	Use terminal-capped value downstream
Terminal limit higher than adjusted ampacity	Derating result	Use adjusted value and keep factor stack
Material change proposed	Terminal material marking and conductor range	Rerun material comparison worksheet
Unknown terminal marking	Incomplete equipment basis	Find manufacturer data before using the result

Formula basis

Final ampacity basis = lower of adjusted conductor ampacity and equipment termination limit.

Conductor rating is the insulation temperature rating selected in the calculator.
Adjustment basis is the temperature rating used before ambient and conductor-count factors.
Terminal limit is the equipment connection temperature rating selected or verified for the installation.
Final ampacity is the capped value carried into load, OCPD, and documentation review.

Worked examples

90C conductor with 75C equipment terminalsRecord the adjusted ampacity from the calculator, then compare it with the 75C terminal limit and carry forward the lower value.

Material change after wire-size resultIf the design changes from copper to aluminum, verify the terminal material marking and conductor range before reusing any terminal-temperature assumption.

Assumptions. Balanced load and line-to-line voltage assumptions behind this chart.

The worksheet assumes equipment terminal temperature markings are known or will be verified before final use.
The worksheet does not approve a 90C final ampacity unless the equipment, conductor, and installation basis permit it.
The adopted NEC edition, equipment listing, manufacturer instructions, torque data, utility requirements, and AHJ expectations must be verified before final conductor selection.

Code and standard notes. Planning limits that should be checked before final equipment selection.

Use this worksheet as an educational planning record; verify adopted NEC requirements, equipment markings, manufacturer instructions, torque data, utility requirements, and AHJ expectations before final conductor selection.

How to use this chart

1Record conductor ratingWrite the conductor insulation temperature rating used by the calculator before reviewing equipment limits.

2Record terminal markingCopy equipment terminal temperature rating, conductor material marking, conductor range, and manufacturer instruction reference.

3Carry forward the lower valueUse the lower final ampacity after comparing adjusted conductor ampacity with the termination-column or equipment limit.

Worksheet checklist. Record source basis, review gaps, and assumptions before using the chart result.

Capture adjustment basisDocument which conductor temperature rating was used for ambient and conductor-count adjustment calculations.
Capture equipment basisDocument actual terminal rating, material marking, torque instruction, and conductor size range for the equipment.
Capture final ampacityLabel whether adjusted ampacity or terminal ampacity controls before using the value for load and protection review.

Common mistakes to avoid. Review these before turning chart current into an equipment decision.

Using a 90C conductor column as final usable ampacity when the actual equipment terminals are rated lower.
Assuming terminal rating from equipment size or project habit instead of checking markings and manufacturer instructions.
Changing conductor material after calculation without rechecking terminal compatibility, torque, and conductor range.

Frequently asked questions

These answers explain how to use the chart without turning a quick reference into a final design decision.

Can 90C insulation always be used at 90C ampacity?

No. The insulation rating may support adjustment calculations, but final ampacity is often limited by equipment terminal ratings.

Why does the calculator ask for termination rating?

It makes the final cap explicit so a conductor-only ampacity is not carried into equipment with a lower terminal limit.

What if terminal markings are not visible?

Treat the result as incomplete until the equipment marking, listing, or manufacturer instruction can be verified.