Customizing reference tables

Create custom reference tables to override NEC 2026 system defaults with organization-specific values or alternative code requirements.

Viewing existing tables

Go to Settings > Reference Tables.
Select scope: System, Organization, or User.
Select table from dropdown (e.g., nec_310_16_cu_75).
Table data displays in JSON format.
System tables are read-only (grayed out).

Creating custom tables

At organization level:

Navigate to Settings > Reference Tables.
Select Organization scope.
Click Add Custom Table.
Enter table key (must match system table key to override).
Enter JSON data.
Click Save.

At user level:

Select User scope.
Follow same process as organization level.
Affects only your sizing calculations.

Temperature derating customization

Override ambient temperature correction factors:

System table structure (`nec_310_15_b_1_ambient_correction`):

{
  "factors": {
    "60": {
      "20": 1.08,
      "25": 1.04,
      "30": 1.00,
      "35": 0.96,
      "40": 0.91,
      ...
    },
    "75": {
      "20": 1.05,
      "25": 1.03,
      "30": 1.00,
      ...
    },
    "90": {
      "20": 1.04,
      "25": 1.02,
      "30": 1.00,
      ...
    }
  }
}

Keys: {termination_temp: {ambient_temp: correction_factor}}

Example customization: Increase ambient temperature factors for extreme climates:

{
  "factors": {
    "75": {
      "45": 0.85,
      "50": 0.80,
      "55": 0.75
    }
  }
}

This adds higher temperature values beyond NEC defaults.

Ampacity table customization

Override conductor ampacities:

System table structure (`nec_310_16_cu_75`):

{
  "14": 25,
  "12": 30,
  "10": 40,
  "8": 55,
  "6": 75,
  "4": 95,
  "2": 130,
  ...
}

Example customization: Reduce ampacities for conservative design:

{
  "14": 20,
  "12": 25,
  "10": 35
}

Only specified sizes are overridden; others use system values.

Motor FLC table customization

Modify motor full-load currents:

System table structure (`nec_430_250_motor_flc_3ph`):

{
  "voltage": {
    "460": {
      "1": 1.1,
      "5": 4.8,
      "10": 9,
      "50": 43,
      ...
    }
  }
}

Example customization: Add non-standard motor sizes:

{
  "voltage": {
    "460": {
      "7": 6.0,
      "12": 10.5
    }
  }
}

Adds 7 HP and 12 HP motor currents.

Standard OCPD sizes

Override available breaker/fuse ratings:

System table structure (`nec_240_6_standard_ocpd_sizes`):

{
  "sizes": [15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, ...]
}

Example customization: Remove non-standard sizes your company doesn't stock:

{
  "sizes": [15, 20, 30, 40, 50, 60, 70, 80, 100, 125, 150, 200, 225, 400, 600, 800]
}

Ensures sizing only selects stocked breaker sizes.

Multiplier customization

Change continuous load or motor multipliers:

System table structure (`nec_430_22_motor_conductor_multiplier`):

{
  "multiplier": 1.25
}

Example customization: Use more conservative multiplier:

{
  "multiplier": 1.35
}

Increases safety margin for motor conductors.

Testing custom tables

After creating custom table:

Create a test component (cable, motor, etc.).
Run sizing calculation.
Verify sizing uses custom table values.
Check sizing results panel for selected sizes.
Compare to expected results.

If custom table not applied:

Verify table key matches system table key exactly
Check scope (org vs user)
Ensure JSON format is valid
Review error messages

Organization-level custom tables automatically apply to all org members:

Best practices:

Document why custom tables created
Note deviations from NEC
Get approval before publishing org-wide
Test thoroughly with representative designs
Communicate changes to team

Reverting to system defaults

Delete custom table:

Navigate to custom table in settings.
Click Delete.
Confirm deletion.
System table values apply immediately.

Or set scope to System:

Simply use System scope for new sizing
Custom tables remain but don't apply

Table validation

Custom tables are validated on save:

Validation checks:

JSON format correct
Required keys present
Values in valid ranges
Data types correct

Invalid tables are rejected with error message explaining issue.

Advanced: Alternative code books

To implement full alternative code book (CEC, IEC):

Create organization-level tables for all NEC tables.
Populate with CEC or IEC equivalent data.
Rename table keys to match alternative standard.
Update code rules in organization settings.

This requires significant effort - consult ekx support for assistance.

Reference tables overview - Understanding reference tables
Cable sizing - How ampacity tables are used
OCPD sizing - How motor and OCPD tables are used