Calculate DC resistance of copper or aluminum wires with temperature correction, parallel conductors, and mm²/AWG input. Supports IEC 60228 & NEC Table 8 for accurate voltage drop and power loss estimation. Accurately compute the DC resistance (in ohms) of electrical conductors based on material, cross-section, length, temperature, and parallel configuration. Designed for engineers sizing feeders, analyzing losses, or verifying compliance with IEC 60228 and NEC Chapter 9. Why Resistance Matters in Real Systems A 0.1 Ω resistance in a 100 A DC circuit causes 10 V drop and 1 kW of wasted heat Aluminum’s higher resistivity requires ~56% larger cross-section than copper for equal performance Operating at 75°C vs. 20°C increases copper resistance by over 20% Two parallel conductors halve total resistance—but only if perfectly balanced Core Calculation Method The tool applies the temperature-corrected resistivity formula: R = ρ20 · (1 + α · (T - 20)) · L / A · (1 / N) Where: R: Total DC resistance (Ω) ρ20: Resistivity at 20°C (Cu: 1.724×10-8 Ω·m, Al: 2.826×10-8 Ω·m) α: Temperature coefficient (Cu: 0.00393 /°C, Al: 0.00403 /°C) T: Conductor operating temperature (°C) L: Length in meters A: Cross-sectional area in m² (auto-converted from mm² or AWG per IEC 60228) N: Number of identical parallel conductors Note: This calculation assumes uniform current distribution and homogeneous conductor material. Not valid for high-frequency AC. Material Comparison Example Scenario: Select conductor for a 150 m, 80 A DC link at 600 V. Max allowable drop: 3% (18 V). Option Size Area (mm²) R (Ω) V Drop (V) Verdict Copper 2 AWG 33.6 0.077 6.16 ✅ Acceptable Aluminum 1/0 AWG 53.5 0.076 6.08 ✅ Acceptable, lower cost Result: Aluminum achieves comparable performance with proper upsizing—validating cost-effective design. Key Limitations No AC effects: Skin effect, proximity effect, and inductance are ignored Uniform temperature assumed: Does not model thermal gradients along the cable Ideal parallel balance: Assumes identical impedance in all parallel paths Stranding factor not applied: Uses nominal area; real stranded wire may have 1–2% higher resistance Industry-Specific Applications Field Use Case Why It Matters Solar PV String-to-combiner wiring Every 0.5% power loss reduces annual energy yield Battery Energy Storage Inter-rack busbars High pulse currents make low R critical for efficiency Industrial Control 24VDC sensor loops Excessive drop causes false signals or relay chatter EV Charging DC fast charger cables I²R heating limits continuous current rating Audio Engineering Speaker wire runs Resistance affects damping factor and bass response For Professionals Who Specify conductor materials and sizes to meet voltage drop limits in renewable energy systems Quantify I²R losses in DC power distribution for energy efficiency audits Verify compliance with NEC Chapter 9 Table 8 or IEC 60228 resistivity requirements Design low-voltage control circuits where even 0.5V drop matters Teach the relationship between resistivity, temperature, and conductor geometry Reference Standards IEC 60228: Standardizes conductor cross-sections and maximum DC resistance values NEC Chapter 9, Table 8: Provides DC resistance data for copper conductors at 75°C IEEE 835: Recommended practice for calculating conductor resistance with temperature correction BS 6361: British standard for resistivity of copper and aluminum conductors Frequently Asked Questions How does temperature affect wire resistance? Resistance increases linearly with temperature. For every 10°C rise, copper resistance increases by ~4%. Always use operating temperature—not ambient—for accurate calculations. Why is my calculated resistance different from the cable datasheet? Datasheets list maximum DC resistance at 20°C. This calculator computes actual resistance at your specified temperature and length, including parallel conductors—providing a more realistic value for design. Can I use this for AC circuits? Only for rough estimates. AC resistance includes skin effect and proximity effects. Use an AC impedance calculator for final design. Does AWG to mm² conversion affect accuracy? Yes—this tool uses standard cross-sectional areas from IEC 60228 (e.g., 10 AWG = 5.26 mm²), not nominal values. This ensures compliance with international standards.

Calculate maximum cable length for DC, single-phase, two-phase, and three-phase systems while respecting voltage drop limits and insulation temperature ratings. Supports copper/aluminum, parallel conductors, and IEC 60364 & NEC Article 215 compliance. When You Need This Calculation Determining how far a 24V DC solar panel can be from its charge controller Sizing feeders for a 480V three-phase motor located 500 m from the main panel Verifying if a 230V lighting circuit can extend to the end of a long corridor without flickering Designing low-voltage DC distribution in a data center with strict efficiency targets Checking if existing wiring can support a new high-power load without exceeding temperature ratings How Maximum Length Is Determined The tool solves the inverse of Ohm's Law: L_max = (V_drop × A) / (ρ × I × N) Where: L_max: Maximum allowable length (m) V_drop: Allowable voltage drop (V) A: Conductor cross-sectional area (mm²) ρ: Resistivity at operating temperature (Ω·mm²/m) I: Load current (A) N: Number of parallel conductors Note: For AC systems, the formula includes power factor and phase configuration. Temperature & Insulation Rating Conductor temperature affects both resistance and insulation life. This calculator uses temperature-corrected resistivity based on: Insulation Type IEC/CEI NEC Typical Applications PVC 70°C 60–75°C General wiring, indoor circuits XLPE/EPR 90°C 90°C Outdoor, buried, industrial Mineral Insulated 105°C 90°C High-temperature environments, fire-rated THHN/XHHW 90°C 75–90°C Commercial buildings, wet locations Industry-Specific Applications Field Use Case Why It Matters Solar PV String-to-combiner box distance Excessive drop reduces system efficiency and MPPT performance Industrial Motors Feeder from panel to motor Low voltage causes torque reduction and overheating Lighting Systems Long runs in corridors or tunnels 3% max drop ensures consistent brightness and lamp life Data Centers DC power distribution units (PDUs) Efficiency loss directly impacts PUE and cooling load EV Charging From transformer to charging station High currents require careful length planning to avoid voltage sag Reference Standards IEC 60364: Electrical installations in buildings — limits voltage drop to 3% for lighting, 5% for motors NEC Article 215: Requires voltage drop not exceed 3% for branch circuits, 5% total from source to outlet IEEE 141: Recommended practice for electric power distribution in industrial plants UL 486A/B: Wiring device standards including temperature ratings Frequently Asked Questions Why is cable length limited by temperature? Conductors heat up under load. If temperature exceeds insulation rating (e.g., 70°C PVC), it can degrade over time. This calculator ensures both voltage drop and thermal safety are met. Can I use this for underground cables? Yes, but ensure you input the actual operating temperature. Underground cables may run hotter due to soil resistivity and lack of airflow. What is the difference between % and V voltage drop? Percentage drop is relative to supply voltage (e.g., 3% of 230V = 6.9V). Use % for general design; use V when specifying exact tolerance (e.g., motor starter requires ≤10V drop). Does this support multi-core cables? Yes—select 'Multipolar' or specific types like Tripolar, Quadrupolar, etc. The tool assumes all conductors are identical in size, material, and length.

Free online cable power loss calculator. Instantly compute I²R losses, voltage drop, and efficiency for DC/AC systems — supports copper, aluminum, and parallel conductors. How much power is lost as heat in your wires? Enter voltage, load, length, and wire size to instantly calculate I²R losses, voltage drop, and circuit efficiency — compliant with IEC 60364 and NEC standards. Supported Systems & Parameters System Types Direct Current (DC) Single-phase AC Two-phase Three-phase (3-wire or 4-wire) Input Parameters Voltage: Phase-to-neutral (single-phase) or phase-to-phase (polyphase) Load Power: In kW or VA Power Factor: 0–1 (default: 0.8) Wire Size: Cross-sectional area (mm² or AWG) Material: Copper (Cu) or Aluminum (Al) Length: One-way distance (meters) Operating Temperature: Auto-adjusted based on insulation type (PVC, XLPE, etc.) Parallel Conductors: Supported for higher current capacity Output Results Conductor resistance (Ω/km) Total circuit resistance (Ω) Power loss (W or kW) Energy loss (kWh/year, optional) Voltage drop (% and V) Temperature-corrected resistance Compliant with IEC 60364 and NEC Article 310. Designed for electrical engineers, solar installers, and industrial designers.

Calculate the maximum admissible let-through energy (I2t = k2S2) for copper or aluminum cables based on IEC 60364 standards. Ensure your protective devices can clear faults before cables overheat. How It Works This tool computes the highest I²t (in A²·s or kA²·s) a cable can safely withstand during a short circuit, using the formula: I²t max = k² × S² Where: S = conductor cross-sectional area (mm²) k = material & insulation constant per IEC 60364-5-54 Input Parameters Conductor Type: Phase, single-core PE, or multi-core PE Wire Size: Cross-section in mm² (e.g., 2.5, 10, 95) Material: Copper (Cu) or Aluminum (Al) Insulation Type: Thermoplastic (PVC) Thermosetting (XLPE / EPR) Mineral-insulated (bare or PVC-covered, various conditions) Output Results Admissible let-through energy (I²t) in kA²·s Reference to IEC 60364-4-43 & IEC 60364-5-54 Guidance for comparing with protective device’s I²t rating Frequently Asked Questions (FAQ) What is admissible I2t for a cable? It’s the maximum fault energy (I²t) a cable can absorb during a short circuit without damaging its insulation or conductor—calculated as k²S² per IEC standards. How is the k factor determined? The k value depends on conductor material (Cu/Al), insulation type, and initial/final temperatures. Standard values are defined in IEC 60364-5-54 Table 43A. Why does insulation type affect I2t? Different insulations tolerate different final temperatures during a fault (e.g., PVC: 160°C, XLPE: 250°C). Higher temperature limits → higher k → greater I²t capacity. Can I use this for DC systems? This calculator follows IEC AC standards. For DC, thermal withstand is similar, but verify protection coordination separately as DC arcs behave differently. How do I check if my breaker is compatible? Compare the cable’s admissible I²t (from this tool) with the breaker’s actual let-through I²t (from its datasheet). The breaker’s I²t must be lower than the cable’s value. Applications Cable Sizing Verification: Confirm selected cables meet thermal withstand requirements during short circuits. Protection Coordination: Ensure fuses or circuit breakers operate fast enough to protect conductors. Compliance with IEC 60364: Demonstrate adherence to international electrical installation standards. Design Review: Validate existing installations during upgrades or safety audits. Training & Education: Teach electrical safety principles using real-world I²t calculations. Who Should Use This Tool? Electrical design engineers Project engineers in industrial & commercial buildings Electrical inspectors and safety auditors Contractors and installers working to IEC standards Students of electrical engineering or power systems

Calculate derated ampacity of low-voltage insulated conductors (≤1 kV) per IEC 60364-5-52. Accounts for ambient temperature, harmonics, multiple circuits, and parallel conductors. When You Need This Calculation Selecting cable size for a 400V three-phase motor feeder Verifying if existing wiring can support a new lighting circuit Designing a low-voltage distribution board with multiple outgoing circuits Ensuring compliance with IEC 60364 for international projects Evaluating cable performance in high-harmonic environments (e.g., VFDs, LED drivers) How Current-Carrying Capacity Is Determined The tool implements the following formula: I_max = I_base × K_temp × K_harmonic × K_circuit × K_parallel Where: I_max: Maximum continuous current (A) I_base: Base current from IEC 60364-5-52 Table B.52.x K_temp: Ambient temperature correction factor (Table B.52.14) K_harmonic: Harmonic derating factor (based on THD) K_circuit: Multiple circuits in conduit factor (Table B.52.17) K_parallel: Parallel conductors factor (if applicable) Note: All values are derived directly from IEC 60364-5-52 tables. No empirical assumptions. Installation Methods & Derating Factors Method Code Description Derating Factor Open air 1-A1 Single conductor exposed to air 1.0 In conduit 1-B1 Multiple conductors in metal or PVC conduit 0.8–0.9 Buried 1-D1 Directly buried in soil 0.7–0.8 Trunking 1-C1 Multiple circuits in open tray 0.85 Underground duct 1-E1 Conduit in underground duct 0.75 Industry-Specific Applications Field Use Case Why It Matters Industrial Plants Motor feeders with VFDs High harmonic content requires derating to prevent overheating Data Centers Low-voltage power distribution units (PDUs) Multiple circuits in conduits demand accurate derating for safety Commercial Buildings Lighting and HVAC circuits Compliance with IEC 60364 ensures fire safety and code approval Renewable Energy DC PV array to inverter cables Long runs require careful sizing to avoid voltage drop and overheating Transportation Electric vehicle charging stations High-current DC circuits need precise thermal management Reference Standards IEC 60364-5-52: Selection and erection of electrical equipment — Wiring systems IEC 60364-5-52 Annex B: Tables B.52.2 to B.52.13 — Current-carrying capacities NEC Article 310: Conductors for general wiring (equivalent in some regions) BS 7671: Requirements for electrical installations (UK equivalent) Frequently Asked Questions Why is ambient temperature important for cable rating? Higher ambient temperature reduces conductor's ability to dissipate heat. The calculator applies a correction factor from IEC 60364-5-52 Table B.52.14 to ensure temperature does not exceed insulation limits. How does harmonic distortion affect cable capacity? Harmonics increase RMS current and cause additional heating. The calculator uses THD input to apply a derating factor, typically reducing allowable current by 10–20% for high-harmonic loads. Can I use this for underground cables? Yes, but select 'buried' or 'direct earth' installation method and input soil thermal resistivity. Underground cables have lower heat dissipation, so ratings are significantly reduced. What is the difference between 'conductors for circuit' and 'circuits in same conduit'? 'Conductors for circuit' refers to current-carrying conductors in one phase (e.g., 3 for three-phase). 'Circuits in same conduit' means multiple independent circuits sharing a duct, which increases heat buildup and requires derating.

This tool calculates the maximum continuous current-carrying capacity of mineral-insulated bare conductors rated at 750V, based on Tables B.52.6 to B.52.9 of IEC 60364-5-52. It supports copper or aluminum conductors under various installation conditions and environmental corrections. How Current-Carrying Capacity Is Determined The calculator implements the following formula derived directly from IEC 60364-5-52: Imax = Ibase × Ktemp × Kcircuit × Kparallel Imax: Maximum continuous current (A) Ibase: Base current from IEC 60364-5-52 Tables B.52.6–B.52.9 Ktemp: Ambient temperature correction factor Air temperature: Table B.52.14 Ground temperature: Table B.52.15 Soil thermal resistivity: Table B.52.16 Kcircuit: Reduction factor for multiple circuits in the same conduit (Table B.52.17) Kparallel: Parallel conductors factor (identical conductors share load; total current equals sum of individual ratings) Note: All values are derived directly from IEC 60364-5-52 tables. No empirical assumptions or approximations are used. Input Parameters Method of Installation: As defined in IEC 60364-5-52 Table A.52.3 (e.g., open air, buried, in conduit). Not all methods are recognized in every country’s regulations. Conductor Material: Copper (Cu) or Aluminum (Al) Type: PVC-covered or bare exposed to touch (metallic sheath temperature limit: 70 °C) Bare not exposed to touch and not in contact with combustible material (sheath temperature limit: 105 °C) Wire Size (mm²): Cross-sectional area of the conductor Phase Conductors in Parallel: Identical conductors can be connected in parallel; total permissible current is the sum of individual core ratings Ambient Temperature: Temperature of surrounding medium when unloaded Circuits in Same Conduit: Number of independent circuits sharing one duct (e.g., two lines for two motors) Output Results Maximum continuous current (A) Corrected value for ambient temperature Reduction factor for multiple circuits Industry-Specific Applications Field Use Case Why It Matters Industrial Plants Motor feeders, high-temperature zones MI cables withstand fire and mechanical stress; accurate ampacity ensures safety Data Centers Critical power distribution Reliability under fault conditions requires precise thermal rating Commercial Buildings Emergency lighting, fire pumps Compliance with fire safety codes (e.g., BS 7671, IEC 60364) Transportation Railway signaling, tunnel power High reliability in confined, high-risk environments Who Should Use This Tool? Electrical design engineers selecting MI cable sizes for industrial projects Project managers verifying compliance with IEC 60364 for international tenders Inspectors and authorities validating installations against code requirements Contractors ensuring safe and efficient field installations Students and educators studying real-world application of IEC derating principles Frequently Asked Questions What is the 125% rule in electrical wiring? The NEC 125% rule requires that conductors supplying continuous loads (operating more than 3 hours) be rated at least 125% of the load current. For example, a 40 A continuous load requires a conductor rated for at least 50 A. This calculator provides the conductor’s ampacity; circuit protection must still comply with local code rules like this one. Can a 4 mm² cable carry 40 A? Under ideal conditions (open air, 30 °C, copper), a 4 mm² bare conductor has a base ampacity of approximately 32–35 A. After derating for temperature or conduit installation, it may drop to 25–28 A. Therefore, 4 mm² is insufficient for a 40 A load. Use 6 mm² or larger. What is the current carrying capacity of an ACSR conductor? ACSR (Aluminum Conductor Steel Reinforced) is used in overhead transmission lines, not low-voltage MI systems. Its ampacity ranges from 120 A (#2) to 240 A (2/0) depending on weather and spacing. This calculator does not apply to ACSR conductors. Is this calculator valid for underground installations? Yes. Select “buried” or “direct earth” installation method and input soil thermal resistivity. The tool applies correction factors from Tables B.52.15 and B.52.16 to account for reduced heat dissipation. What’s the difference between “exposed to touch” and “not exposed”? Exposed to touch: sheath temperature limited to 70 °C for safety. Not exposed and not in contact with combustible material: sheath can reach 105 °C, allowing higher current. Always verify local regulations before using the higher rating. Reference Standards IEC 60364-5-52: Selection and erection of electrical equipment — Wiring systems IEC 60364-5-52 Annex B: Tables B.52.6 to B.52.17 BS 7671: Requirements for electrical installations (UK) NEC Article 310: Conductors for general wiring (US equivalent principles) Related Tools Insulated Conductor Ampacity Calculator (PVC/XLPE) Busbar Current-Carrying Capacity Calculator Cable Derating Factor Lookup

Calculate cable operating temperature per IEC 60364-5-52 & NEC. Check if PVC (70°C) or XLPE (90°C) limits are exceeded. Learn what is too hot for wires and how to avoid overheating. Input Parameters Current Type: DC, single-phase AC, two-phase, or three-phase (3-wire or 4-wire system) Voltage (V): Phase-to-neutral for single-phase; phase-to-phase for polyphase systems Load Power (kW or VA): Rated power of connected equipment (used to compute operating current) Power Factor (cos φ): Ratio of real to apparent power (range: 0–1; default: 0.8) Installation Method: Per IEC 60364-5-52 Table A.52.3 (e.g., free air, in conduit, direct buried) Conductor Material: Copper (Cu) or Aluminum (Al)—impacts resistivity and heat generation Insulation Type: PVC (70°C) or XLPE/EPR (90°C)—sets maximum allowable temperature Wire Size (mm²): Cross-sectional area of the conductor, directly influencing current-carrying capacity Ambient Temperature (°C): Surrounding medium temperature (air or ground), affecting heat dissipation Circuits in Same Conduit: Number of loaded circuits in one duct—used to apply group derating per IEC Table B.52.17 and NEC adjustment factors Output Results Steady-state cable conductor temperature (°C and °F) Compliance check: Pass/Fail against insulation thermal limits Applied correction factors (ambient temperature, installation grouping, soil thermal resistivity where relevant) Reference to applicable tables: IEC 60364-5-52 Tables B.52.14–B.52.17 and NEC Article 310 How the Calculation Works This calculator estimates conductor temperature using a simplified thermal equilibrium model based on IEC 60364-5-52 Annex B: First, it computes the operating current from load power, voltage, and power factor. Then, it applies derating factors for ambient temperature, installation method, and circuit grouping (per IEC Tables B.52.14–B.52.17 and NEC Table 310.15(B)(3)(a)). Finally, it compares the resulting thermal load against the insulation’s maximum rated temperature (70°C for PVC, 90°C for XLPE/EPR). Note: This is a steady-state approximation for normal operating conditions—not intended for short-circuit or transient analysis. Use Cases This calculator supports real-world electrical design and safety verification across multiple sectors: Residential Wiring: Verify that lighting or outlet circuits won’t overheat under peak load. Commercial Buildings: Assess cable temperature in conduit bundles for HVAC, elevators, or data centers. Industrial Installations: Validate conductor sizing for motors, pumps, or machinery with high duty cycles. Renewable Energy Systems: Check DC cable thermal performance in solar PV or battery storage setups. Retrofit & Maintenance: Diagnose overheating issues by comparing actual load vs. safe operating temperature. Designed to complement NEC Article 310 and IEC 60364-5-52 compliance workflows. Common Cable Temperature Ratings Rating Insulation Type Max Temp Typical Use 60°C PVC (older types) 60°C Indoor, limited load 75°C THHN, XHHW 75°C Commercial, industrial 90°C XLPE, EPR 90°C High temp, outdoor, wet locations Frequently Asked Questions (FAQ) What is the maximum operating temperature for cables? The maximum operating temperature depends on the insulation type. Common ratings are: PVC (70°C): Used in general-purpose wiring (e.g., Romex). XLPE/EPR (90°C): For high-temperature or outdoor applications. 75°C rated wire: Often used in commercial settings; allows higher current derating. Exceeding these limits can cause insulation breakdown, short circuits, or fire. How hot is too hot for electrical wires? For most household cables, anything above 70°C (158°F) is considered too hot if it's PVC-insulated. XLPE-rated cables can handle up to 90°C (194°F). If you feel warmth on a cable during normal use, it may indicate an overload—check your load and conductor size. What is the safe temperature for cable? The "safe" temperature is defined by the insulation rating: 70°C for PVC, 90°C for XLPE/EPR. The operating temperature must not exceed this under any load condition. Always apply NEC or IEC derating factors for ambient heat, bundling, and installation method. Can cold weather damage cables? Cold weather itself doesn't damage cables, but extreme cold (below -20°C) can make PVC brittle and prone to cracking during installation. Most cables are rated for installation down to -10°C to -20°C, depending on type. Avoid pulling or bending cables when frozen. What is the installation temperature for cables? Installation temperature refers to the ambient temperature during cable pulling and termination. Most standards (like NEC and IEC) require that cables be installed at temperatures above their minimum rating (typically -10°C to 0°C) to prevent damage. Never install cables in freezing conditions unless they're rated for low temperature. What is the difference between 75°C and 90°C wire? The difference lies in insulation material and thermal rating: 75°C wire: Typically has PVC or THHN insulation; used indoors with moderate loads. 90°C wire: Uses XLPE or EPR; allows higher ampacity and better performance in hot environments. In the NEC, 90°C-rated conductors can be used for ampacity calculations, but only if the circuit breaker is sized appropriately (e.g., 75°C terminations). What does 60/75°C temperature rating on breaker mean? This refers to the termination temperature rating of the circuit breaker. It means: 60°C: Maximum allowable temperature at the terminal under normal load. 75°C: Higher rating allows use of 90°C-rated conductors without derating (if all connections meet 75°C standard). Always match wire temperature rating to the lowest-rated component in the circuit. What is the meaning of cable temperature rating? The cable temperature rating is the maximum continuous operating temperature the insulation can withstand without degrading. It’s determined by the insulation material (e.g., PVC = 70°C, XLPE = 90°C) and affects how much current the cable can safely carry. This rating is critical for compliance with NEC Article 310 and IEC 60364-5-52. What is the normal operating temperature of V-90 cables? V-90 cables are typically XLPE-insulated cables rated for 90°C. Their normal operating temperature should remain below this limit. In practice, under full load, they may reach 70–85°C depending on ambient conditions and installation method. Which standards does this calculator use? The tool applies derating methods from IEC 60364-5-52 (international) and aligns with NEC (NFPA 70) Article 310 (U.S.) for ambient temperature, grouping, and installation conditions. It references IEC Tables B.52.14–B.52.17 for correction factors. Why does my result show a temperature above 90°C? This typically means the current exceeds the safe capacity of the selected cable size and installation method. For example, 50 A on a 1.5 mm² PVC-insulated cable will likely breach thermal limits. Always verify against local codes and consider upsizing the conductor. Safety Notice This tool is for preliminary engineering assessment only. Always verify results with local electrical codes, manufacturer data, and a qualified professional. Overloaded cables can overheat, melt insulation, and cause fire—never rely solely on automated tools for final design approval.

Find the right wire size for solar inverters, home circuits & more. Supports DC/AC, voltage drop, IEC 60364. Free tool for engineers & DIYers. What size wire for a 2000W inverter? Can I use 10 AWG for my solar panels? Get the correct cable size based on load, voltage, distance, and allowable voltage drop — compliant with IEC 60364-5-52. How It Works This tool calculates the minimum conductor cross-sectional area (mm²) according to IEC 60364-5-52, considering: System type: DC, single-phase or three-phase AC Voltage, load power, and power factor Cable length and max allowed voltage drop (typically 3%) Ambient temperature, insulation type (PVC/XLPE), and installation method Grouping derating and parallel conductors Designed for electrical engineers, solar installers, and students who need fast, code-compliant cable sizing. Common Questions What size wire for a 2000W inverter? For a 12V system over 10ft with 3% voltage drop, you need at least 2/0 AWG (70 mm²) copper cable. Can I use 10 AWG for my solar panels? Yes — if your array current is under 30A and the distance is less than 50ft (15m) at 48V. How to calculate DC cable size with voltage drop? Enter your DC voltage, load power, one-way distance, and max % drop. The tool applies IEC derating and returns the minimum mm².

Calculate the maximum continuous current-carrying capacity of copper or aluminum busbars based on size, material, ambient temperature, ventilation, and installation conditions. Supports rectangular and round shapes. How to Calculate Busbar Current-Carrying Capacity? The calculation is based on thermal equilibrium principles, where heat generated by current equals heat dissipated to the environment. The core formula used in this calculator follows IEC 60890 and IEEE 738 standards: I = K × √(A × ΔT) × f₁ × f₂ × f₃ I = Maximum continuous current (A) K = Material factor (Copper ≈ 1.0, Aluminum ≈ 0.6) A = Cross-sectional area (mm²) ΔT = Allowable temperature rise (°C), typically 30–50°C f₁ = Ventilation factor (e.g., open air vs. enclosed) f₂ = Position factor (horizontal, vertical, stacked) f₃ = Surface factor (unpainted, dark painted) Step-by-Step Calculation Example Copper flat bar: 100 mm × 10 mm, ambient 35°C, ΔT = 30°C, open air, horizontal, unpainted Area A = 100 × 10 = 1000 mm² K = 1.0 (copper) √(A × ΔT) = √(1000 × 30) = √30,000 ≈ 173.2 f₁ = 1.0 (open air), f₂ = 0.95 (horizontal), f₃ = 1.0 (unpainted) I = 1.0 × 173.2 × 1.0 × 0.95 × 1.0 ≈ 1645 A What Is the Rule of Thumb for Busbar Sizing? While precise calculation is recommended, engineers often use these **rules of thumb** for quick estimation: Rule Application Accuracy 1.25 Rule Size busbar at 125% of full-load current (common in US NEC) Low accuracy; for general design only Thermal Rule Use IEC/IEEE formulas with actual parameters High accuracy; recommended for final design Material Factor Aluminum carries ~60% of copper’s current per mm² Medium accuracy; useful for material comparison How Many Amps Can a Bus Bar Handle? The maximum current depends on multiple factors. Here are typical values for common configurations: Busbar Type Dimensions Max Current (A) Notes Copper Flat Bar 100×10 mm ~2800 A Open air, 30°C rise Aluminum Flat Bar 100×10 mm ~1700 A Same conditions as above Round Copper Φ50 mm ~1200 A Less efficient than flat bar Frequently Asked Questions (FAQ) How to decide busbar size? Follow these steps: Determine required current (from load calculation) Select material (copper for high performance, aluminum for cost) Choose shape (flat bars are more efficient) Apply correction factors for temperature, ventilation, and position Use IEC or IEEE formulas to compute ampacity Verify against standard sizes (e.g., 100×10, 120×12) What is the IEC standard for busbar sizing? The primary standard is IEC 60890, which defines methods for calculating the current-carrying capacity of bare conductors, including busbars. It considers material, geometry, ambient temperature, and cooling conditions. What is the NEC code for busbars? In the US, NEC Article 366 covers busways and busbars. It specifies minimum conductor sizes, insulation requirements, and installation rules. However, it does not provide direct ampacity tables—engineers must use IEC/IEEE methods or manufacturer data. What is the formula for earthing busbar size? Earthing (grounding) busbars are sized based on fault current and duration. The formula is: S = √(I²t / k) Where: - S = Cross-sectional area (mm²) - I = Fault current (kA) - t = Duration (s) - k = Material constant (e.g., 137 for copper, 84 for aluminum) What is the 1.25 rule in electrical? The "1.25 rule" means sizing conductors or equipment at **125% of the full-load current** to account for continuous operation (over 3 hours). This is required by NEC for motors and some loads, but not for busbars unless specified. Why is it called a busbar? The term "busbar" comes from the word "bus," meaning a central distribution point. In electrical systems, a busbar acts as a **central power distribution hub**, connecting multiple circuits and distributing electricity like a bus route. Related Tools Transformer Economic Capacity Calculator Cable Ampacity Calculator Conduit Fill Calculator