Sage's Electrical Tools
Select a calculation tool below
Motor Feeder Design
Branch OCP sizing, feeder conductor schedule, EGC, conduit fill, and voltage drop for motor feeders. Supports standard motors, elevator loads, and fire pump motors (NEC 695).
NEC 430
NEC 620
NEC 695
NEC 310
NEC 250.122
✓ Available
Feeder Sizing
Ambient temperature correction factors and conduit fill derating for conductors. Applies NEC 310.15(B) and 310.15(C) adjustment factors.
NEC 310.15(B)
NEC 310.15(C)
NEC 110.14(C)
✓ Available
Transformer OCP & Feeder
Primary & secondary OCP sizing per NEC Table 450.3(B). Full-load current, conductor sizing, and available fault current at transformer secondary.
NEC 450.3
NEC 240.6
NEC 310.16
NEC 250.122
✓ Available
Conduit Fill Calculator
Mixed conductor conduit fill for any combination of wire sizes and insulation types. Supports EMT, IMC, RMC, PVC, and FMC.
NEC Ch.9 Table 4
NEC Ch.9 Table 5
✓ Available (Beta)
Short-Circuit & AIC Check
Available fault current calculation and interrupting rating verification for OCP devices at the panel.
NEC 110.9
NEC 110.10
IEEE 141
✓ Available
Service Size Calculator
Build a panel or MCC load schedule. Enter loads by type, poles, amps, and demand factor. Calculates total connected and demand kVA, demand current, and minimum service/feeder ampacity.
NEC 220
NEC 215.2
NEC 408
✓ Available
Voltage Drop Calculator
Calculate voltage drop for branch and feeder circuits using NEC Table 9 AC resistance values. Includes one-line diagram, minimum conductor recommendation, and power loss.
NEC 210.19
NEC 215.2
NEC 310.15
✓ Available
Cable Tray Ampacity
Conductor ampacity for cables installed in ladder, ventilated trough, and solid-bottom cable trays. Applies NEC 392 fill and derating rules.
NEC 392
NEC 310.15
NEC Table 310.16
✓ Available
Junction / Pull Box Sizing
Minimum box dimensions for junction and pull boxes based on conduit size, quantity, and angle pulls. Straight and angle pull calculations per NEC 314.28.
NEC 314.28
NEC 314.16
NEC 314.29
✓ Available
Energy Calculator
Electrical energy consumption, demand analysis, power factor correction, and cost estimation tools for commercial and industrial loads.
kWh / kVA
Power Factor
Demand Analysis
✓ Available
Cu ↔ Al Feeder Equivalency
Find equivalent copper and aluminum feeder sizes for any design ampacity. Toggle parallel sets (1–4) to compare conductor sizes, conduit, and EGC across both materials simultaneously.
NEC Table 310.16
NEC 310.10(H)
NEC 250.122
✓ Available
| Project: | Project No.: |
| Engineer of Record: | |
| Date: | Tool: Voltage Drop Calculator — NEC 2026 | |
1 Project Information
▼A System & Circuit Parameters
▼
ⓘ Circuits are calculated in series — the receiving-end voltage of each segment becomes the starting voltage of the next. Add segments in order from source to load. Cumulative voltage drop is tracked across the entire run.
When PF < 1, uses full R·cosφ + X·sinφ formula (NEC Table 9).
Circuits
| # | Segment Description | Current (A) | Load Type | Conductor Size | Sets | Length (ft) | ✕ |
|---|
No segments added yet
ⓘ R and X from NEC Table 9 (75°C, steel conduit Ω/kft); PVC +2%. Formula at PF=1: VD = √3·I·R (3Ø) or 2·I·R (1Ø). At PF<1: VD = factor·I·(R·cosφ + X·sinφ). Ampacity check: CF = √((Tc−Ta)/(Tc−30°C)), NEC 310.15(B)(1)(a), applied to NEC Table 310.15(B)(16) base values.
Results — Voltage Drop Calculation
Code References
1 Project Information
A Panel Configuration
▼
ⓘ Demand factors on Calculate: Receptacle (NEC 220.44 — first 10 kVA @ 100%, remainder @ 50%), HVAC (100% — NEC 220.50), Elevator (NEC 620.13 — by qty), Heater (125% — NEC 424.3(B)). Motor / Lighting / Heater / Equipment / Other use the DF entered in the load schedule table.
B Load Schedule
ⓘ Enter load in Amps or kVA per row — toggle the unit button. kVA auto-calculates from voltage & phase. Demand factors: Receptacle (NEC 220.44), HVAC (NEC 220.50 @ 100%), Elevator (NEC 620.13 by qty), Heater (NEC 424.3(B) @ 125%), Motor/Lighting/Equipment/Other (user-entered DF).
| # | Description | Load Type | Voltage | Phase | Load (A / kVA) | Qty | Demand Factor ? | |
|---|---|---|---|---|---|---|---|---|
| No loads added. Click "+ Add Load" to start. | ||||||||
Results
Code References
1 Project Information
▼2 Feeder Sizing
▼
ⓘ Add all motors served from this feeder. Elevator loads apply NEC 620.61(C) & 430 Part V for OCP, and NEC 620.13(A) & 430.22(E) for conductors. Check Manual FLA to override table lookup (nameplate or 277V motors).
| # | Load Name | Load Type ? | HP | Voltage | Phase | Motor Design ? | OCP Type ? | Manual FLA ? | Del |
|---|
3 Feeder Settings & Voltage Drop
▼
Neutral sized same as phase. Not a CCC — NEC 310.15(C)(1) Ex. No.1
Parallel runs: min. #1/0 AWG per NEC 310.10(H). Each conduit carries one set of phases + EGC.
86.0 °F
Standard = 30°C. Derating per NEC 310.15(B)(1) when > 30°C.
Auto-derived from motor inputs
4 Calculation Results
5 Code References & Assumptions
▼| Project: | Project No.: |
| Engineer of Record: | |
| Date: | Tool: Conductor Ampacity & Derating — NEC 2026 | |
1 Project Information
▼A Feeder Conductor & Conduit Sizing
▼
ⓘ Enter feeder parameters to size phase conductors, neutral (if applicable), EGC, and conduit under actual ambient and fill conditions.
1-Phase 120V/277V (L-N): Phase + Neutral + EGC.
1-Phase 208V/240V/480V (L-L): Phase A + Phase B + EGC — select neutral option in System Configuration.
3-Phase 3-Wire: 3 Phase + EGC (no neutral).
3-Phase 4-Wire: 3 Phase + Neutral + EGC.
For parallel runs (>1 conductor/phase), each conduit is sized independently per NEC 310.10(H).
Each conduit: 1 set of conductors + 1 EGC. Min #1/0 AWG per run (NEC 310.10(H)).
B Combined Derating — Temp × Fill Factor
▼
ⓘ Applies both correction factors simultaneously.
Final Ampacity = Base × CFtemp × AFfill
| Optionally enter load current to verify conductor adequacy.
C Minimum Conductor Size Finder
▼
ⓘ Reverse calculation — enter required conductor ampacity after demand factors (e.g., 125% × motor FLA).
Finds the minimum conductor size whose derated ampacity meets or exceeds the requirement under the given conditions.
Results table shows every available size with full derating breakdown.
D EGC Proportional Sizing — NEC 250.122(B)
▼
ⓘ Per NEC 250.122(B): when ungrounded conductors are increased beyond the NEC minimum for the OCPD, the equipment grounding conductor (EGC) must be increased proportionally in circular-mil area.
Applies to both single and parallel conductor installations.
| Project: | Project No.: |
| Engineer of Record: | Load / Panel: |
| Date: | Tool: Transformer OCP & Feeder Sizing — NEC 2026 | |
1 Project Information
▼2 Transformer Parameters
▼
ⓘ Enter transformer nameplate data. FLC is calculated per NEC definitions: 1-Phase: I = (kVA × 1000) / V | 3-Phase: I = (kVA × 1000) / (√3 × V). OCP sized per NEC Table 450.3(B) for voltages ≤ 1000V, or Table 450.3(A) for primary > 1000V.
3 OCP Configuration — NEC 450.3
▼
ⓘ NEC Table 450.3(B) — Transformers ≤ 1000V (both primary and secondary):
Primary-only: max 125% (≥9A) or 167% (<9A). With secondary OCP: primary max 250%; secondary max 125% (≥9A) or 167% (<9A).
NEC Table 450.3(A) — Primary or secondary > 1000V:
Primary-only: 125% (≥9A) or 167% (<9A). With secondary OCP: primary max 250%; secondary max 125% (≥4A).
OCP is a maximum — always round down to the next lower standard size per NEC 240.6(A). Secondary >1000V: conductor type and size per EOR specification (medium-voltage cable — NEC Article 310 Part III).
4 Calculation Results
5 Code References
Calculation History
Session log — up to 10 most recent calculations | Cleared on page reload
1 Project Information
A Conduit Selection
▼
ⓘ NEC Chapter 9, Note 1: Fill limits — 1 conductor: 53%, 2 conductors: 31%, 3 or more: 40% of internal conduit area. The calculator checks the selected size AND finds the minimum required conduit size for the conductor set entered below.
The Jam Probability section evaluates the classic three-cable jam ratio (conduit ID ÷ cable OD); enter an actual cable OD above to override the value derived from NEC Table 5.
B Conductor Schedule
▼| Wire Size | Insulation Type | Qty | Unit Area (in²) | Row Total (in²) | |
|---|---|---|---|---|---|
| No conductors added — click "+ Add Conductor" | |||||
Results — Conduit Fill Analysis
NEC References
1 Project Information
A Source — Transformer / Generator Data
▼AFC Input Method
ⓘ Typical nameplate %Z: 25 kVA ≈ 1.5–2%, 75 kVA ≈ 2.5–3%, 150 kVA ≈ 3.5%, 225–300 kVA ≈ 5%, 500 kVA ≈ 5.75%, 750–1000 kVA ≈ 5.75–6%. Confirm from transformer nameplate. X/R = 6 is typical for LV distribution transformers.
ⓘ Enter the available fault current from the utility, a prior study, or transformer secondary terminals (symmetrical RMS). Used as the starting point for all downstream calculations.
Generator Configuration
| # | Generator Label | Rating (kVA) | X"d (%) | |
|---|---|---|---|---|
| No generators added — click "+ Add Generator" | ||||
ⓘ Generator fault current: I_sc = kVA × 1000 / (√3 × V × X"d) (3Ø). X"d is the subtransient direct-axis reactance from the nameplate — typically 10–15% for synchronous generators, 20–30% for diesel gensets. For parallel generators at the same bus, fault currents are summed. X/R = 20 is typical for generators.
⚡ Motor Contribution to System Fault Current
ⓘ Running motors back-feed fault current per IEEE 141 (Red Book) / NEC 110.9–110.10. Approximate motor FLA is estimated from total HP at system voltage (η = 0.90, PF = 0.85). Motor contribution is added to source AFC at the transformer secondary bus.
B Distribution Topology — Point-to-Point Feeder Path
▼
ⓘ Add distribution equipment in upstream-to-downstream order (e.g. MDP → DP → LP). Each row defines the feeder conductor from the previous node (or source transformer) to this equipment. The Point-to-Point f-factor method (IEEE 141 / NEC Annex D) cascades fault current from source through each node.
| Equipment Label | Type | Feeder Length (ft) | Conductor Size | Material | Sets/Phase | Conduit Type | |
|---|---|---|---|---|---|---|---|
| No equipment added — use the buttons below to build your distribution topology | |||||||
ADD:
ⓘ Feeder Length = one-way conductor run (ft). Uses NEC Table 9 AC resistance (steel conduit, 75 °C). Enter 0 or leave blank if equipment is directly at the source secondary bus (no feeder impedance).
C Device AIC Rating Check (NEC 110.9)
▼| Device / Description | Location / Panel | Rated AIC (select standard) | Custom AIC (A) | |
|---|---|---|---|---|
| No devices added — click "+ Add Device" | ||||
Results — Short-Circuit Analysis
NEC References
1 Project Information
A Cable & System Parameters
▼
⚠ NEC 392.80(A)(2) requires single conductors in cable tray to be 1/0 AWG or larger. Smaller sizes are not permitted as single conductors in cable tray.
B Cable Tray Parameters
▼
⚠ NEC 392.80(A)(2): Single conductors in solid-bottom cable trays must be derated to 70% of the 75°C ampacity (no-spacing arrangement). Maintained-spacing benefit does not apply in solid-bottom trays.
C Conductor Arrangement — NEC 392.80
▼
ℹ Auto-populated from THHN/XHHW typical OD for selected size. Verify against actual cable data sheet.
NEC 392.80 Arrangement Rules:
• Single conductor, maintained spacing (A)(2)(a): Conductors may use 90°C column if insulation rated 90°C. No derating for ≤3 CCCs.
• Single conductor, no spacing / multi-layer (A)(2)(b–c): 70% of 75°C ampacity. Applies in any tray type.
• Multiconductor, single layer, ladder/vent trough (A)(1)(a): Use 75°C column; derating per NEC 310.15(C)(1) if total CCCs > 3.
• Multiconductor, multi-layer, ladder/vent trough (A)(1)(b): Apply CCC adjustment factor per NEC 310.15(C)(1).
• Multiconductor, solid bottom (A)(1)(c): Additional 80% derating on top of CCC factor.
• Single conductor, maintained spacing (A)(2)(a): Conductors may use 90°C column if insulation rated 90°C. No derating for ≤3 CCCs.
• Single conductor, no spacing / multi-layer (A)(2)(b–c): 70% of 75°C ampacity. Applies in any tray type.
• Multiconductor, single layer, ladder/vent trough (A)(1)(a): Use 75°C column; derating per NEC 310.15(C)(1) if total CCCs > 3.
• Multiconductor, multi-layer, ladder/vent trough (A)(1)(b): Apply CCC adjustment factor per NEC 310.15(C)(1).
• Multiconductor, solid bottom (A)(1)(c): Additional 80% derating on top of CCC factor.
Results — Cable Tray Ampacity
NEC References
1 Project Information
A Pull Configuration
▼
ℹ NEC 314.28 applies to boxes and conduit bodies containing conductors 4 AWG or larger (insulated), systems ≤1000V.
Straight pull: box length ≥ 8× trade size of largest raceway (NEC 314.28(A)(1)).
Angle / U-pull: distance to opposite wall ≥ 6× largest raceway + sum of the other raceway trade sizes on the same wall in the same row (NEC 314.28(A)(2)).
Distance between raceways enclosing the same conductor ≥ 6× the larger raceway trade size.
B Raceway Entries
▼| # | Wall | Trade Size | Qty |
|---|
Results — Minimum Box Dimensions
NEC References
1 Project Information
A Utility Rate Structure
▼Enter 0 if the tariff has no demand charge.
Leave blank to use total connected kW (no diversity).
ℹ Flat-rate model: monthly cost = kWh × rate + billed kW × demand charge. Time-of-use tariffs, ratchet clauses, and PF penalty riders vary by utility — verify against the actual tariff sheet.
B Load Schedule & Operating Profile
▼
ℹ Enter each load in kW or kVA (kVA rows convert via PF). kWh/month = kW × qty × hrs/day × days/wk × 4.333 wk/mo × load factor.
| # | Load Description | Value | Unit | PF | Qty | Hrs/Day | Days/Wk | Load Factor |
|---|
C Power Factor Correction — optional
▼
ℹ Required capacitor kVAR = kW × (tan φ1 − tan φ2). Correcting PF releases apparent-power (kVA) capacity in transformers and feeders and may avoid utility PF penalties. Leave kW blank to skip.
Results — Energy & Cost Analysis
Formulas & Assumptions
Project Information ▾
⚡ Feeder Parameters
ⓘ Enter the design load current and options. The calculator sizes the smallest Cu and Al conductor that meets the ampacity requirement for each parallel-set count, using NEC Table 310.16 (75°C column). Toggle Sets to compare options side-by-side.
📐 Feeder Sizing Results
⚡
Sage's Electrical Tools
Electrical design tools powered by the wisdom of Sage
Our Mission
To provide electrical designers and engineers with fast, and reliable calculation tools that streamline electrical work through wisdom of Sage.
Available Calculators
- ✓Motor Feeder Design — NEC 430, including fire pump motors (NEC 695)
- ✓Conductor Ampacity & Derating — NEC 310.15, ambient temp & conduit fill
- ✓Transformer OCP & Feeder Sizing — NEC 450
- ✓Voltage Drop Calculator — NEC 210.19 / 215.2, single & multi-segment
- ✓Service Size Calculator — Panel Schedule — NEC 220, demand factors
- βConduit Fill Calculator — NEC Chapter 9 Tables (Beta)
- ✓Short-Circuit & AIC Check — NEC 110.9 / 110.10
- ✓Cable Tray Ampacity — NEC 392, NEC 310.15 derating
- ✓Junction / Pull Box Sizing — NEC 314.28 straight, angle & U-pulls
- ✓Energy Calculator — kWh consumption, cost & power factor correction
Disclaimer
All calculations are provided for design reference only. Results must be reviewed and sealed by a licensed Professional Engineer (PE) prior to permit submission or construction use. Sage's Electrical Tools is not a substitute for professional engineering judgment.
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