Reference tables overview

Reference tables contain electrical data used by the sizing engine to calculate conductor ampacity, derating factors, and OCPD sizes according to NEC 2026.

What reference tables are

Reference tables store code-required data:

NEC ampacity tables (310.16, 310.17)
Temperature correction factors (310.15(B)(1))
Conductor adjustment factors (310.15(C)(1))
Motor full-load current tables (430.248, 430.250)
Standard OCPD sizes (240.6)
Motor conductor and protection multipliers (430.22, 430.52)

The sizing engine queries these tables during cable and OCPD sizing calculations.

NEC 2026 default tables

ekx includes NEC 2026 tables as system defaults:

Table Key	NEC Article	Content
nec_310_16_cu_60	310.16	Copper ampacity at 60°C
nec_310_16_cu_75	310.16	Copper ampacity at 75°C
nec_310_16_cu_90	310.16	Copper ampacity at 90°C
nec_310_16_al_60	310.16	Aluminum ampacity at 60°C
nec_310_16_al_75	310.16	Aluminum ampacity at 75°C
nec_310_16_al_90	310.16	Aluminum ampacity at 90°C
nec_310_15_b_1_ambient_correction	310.15(B)(1)	Temperature derating factors
nec_310_15_c_1_adjustment_factors	310.15(C)(1)	Bundling adjustment factors
nec_240_6_standard_ocpd_sizes	240.6	Standard breaker/fuse ratings
nec_430_248_motor_flc_1ph	430.248	Single-phase motor FLC
nec_430_250_motor_flc_3ph	430.250	Three-phase motor FLC
nec_430_22_motor_conductor_multiplier	430.22	Motor conductor sizing (1.25×)
nec_430_52_motor_ocpd_multipliers	430.52	Motor OCPD sizing by type

The current Settings page presents these system rows as read-only reference data. EKX does not currently expose controls there to author overrides.

Resolution scopes

Reference tables use the same hierarchy as component defaults:

System (built-in):

NEC 2026 tables
Cannot be modified
Base for all customization

Organization:

Approved company-wide rows, when provisioned outside the current UI
Applies to all organization members

User:

Approved user-specific rows, when provisioned outside the current UI
Applies only to that user

Organization rows replace system rows with the same key. User rows replace both. Rows are selected whole; partial JSON objects are not merged.

How tables are used in sizing

Cable sizing:

Lookup ambient temperature factor from nec_310_15_b_1_ambient_correction.
Lookup conductor adjustment factor from nec_310_15_c_1_adjustment_factors.
Calculate required base ampacity.
Lookup conductor size from nec_310_16_cu_XX based on material and termination temp.
Return selected conductor size and adjusted ampacity.

OCPD sizing:

Calculate required OCPD current (load × continuous factor).
Lookup next standard size from nec_240_6_standard_ocpd_sizes.
For motors, lookup FLC from nec_430_248 or nec_430_250.
Apply multiplier from nec_430_52_motor_ocpd_multipliers based on device type.
Return selected OCPD size.

Tables provide the code-mandated values for these calculations.

Table data format

Each table type has its own complete, validated JSON structure. The read-only viewer renders that structure in a table-specific format. Because override authoring is not available in the current UI, the public docs intentionally do not present copy-and-paste JSON templates that could drift from runtime validation.

Custom tables remain within the selected code profile and are labeled as custom provenance. They cannot turn an NEC project into a CEC or IEC project.

Reference tables and custom data - Current capabilities and limitations
Cable sizing - How sizing uses ampacity tables
OCPD sizing - How sizing uses OCPD and motor tables