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Engineering Tools

A free toolkit for electrical and lighting engineers. Run quick checks for current, cable size, voltage drop, illuminance, and power factor correction. All calculations run in your browser. Nothing is sent to a server.

Current (Amperage)

Calculate line current from real power, voltage, power factor, and motor efficiency. Supports 1-phase and 3-phase circuits.

Formula: I_line = P / (V · PF · η) for 1-phase · I_line = P / (√3 · V_LL · PF · η) for 3-phase. In Star: V_phase = V_LL/√3, I_phase = I_line. In Delta: V_phase = V_LL, I_phase = I_line/√3.

Result

85.0A
Line current
Phase current (Iph)85.0 A
Phase voltage (Vph)230.9 V
Apparent Power (S)58.8 kVA
Reactive Power (Q)31.0 kVAR
Phase angle (φ)31.8°
Sizing rule of thumb: select breakers ≥ 1.25× this current for continuous loads (NEC) or per IEC 60364 utilisation factor.
Visualization
Power triangle (P · Q · S)
Connection schematic

Cable Size

Pick the smallest cable that satisfies both ampacity and voltage drop. Two standards: IEC 60364-5-52 (Method C, mm² cross-section) or NEC Table 310.16 (single conductor in raceway, AWG sizes). Cu conductors.

Sizes shown are nominal Cu cross-sections. Voltage drop uses Vd = √3 · I · R · L / 1000 (3φ) or Vd = 2 · I · R · L / 1000 (1φ).

Recommended Size

25mm²
Minimum Cu conductor passing both ampacity + Vd
Derated ampacity at this size95.2 A
Voltage drop at this size2.6 V (0.65%)
Sized byVoltage drop
Temperature derating×1.00
Grouping derating×1.00
Reference: IEC 60364-5-52, Method C, copper conductor, single 3-phase loaded circuit. For other installation methods or aluminium, consult full standard.
Visualization
Cable cross-section · Cu cores
Ampacity vs cross-section

Voltage Drop

Standalone Vd calculation for a known cable size. Use to verify a sizing decision or check existing installation.

Vd = 2·I·R·L / 1000 (1φ) · Vd = √3·I·R·L·cos φ / 1000 (3φ). R taken at 70°C operating temperature.

Result

3.77V
Voltage drop along the cable
Drop as % of nominal0.94%
Voltage at load end396.2 V
Power lost in cable377 W
Recommended limits (IEC 60364-5-52 Annex G): lighting circuits ≤ 3% from origin to load · power circuits ≤ 5%. Tighter limits apply to motor starting and harmonic-sensitive loads.
Visualization
Source → cable → load · voltage along the run

Lux (Illuminance)

Average illuminance using the lumen method: E = (N · Φ · CU · LLF) / A. Calculates lux at the floor and at table-top height (0.75 m).

Lux at floor uses RCR(h_room). Lux at table top uses RCR(h_room − 0.75 m). CU is interpolated from typical direct-luminaire tables.

Result

700lx
Average lux at floor
Lux at table top (0.75 m)820 lx
Total luminous flux installed70,000 lm
Room area80 m²
Watts / m² (LPD)9.0
Efficacy (system lm/W)97.2
Typical targets (EN 12464-1): office desks 500 lx · meeting rooms 500 lx · corridors 100 lx · warehouse aisles 200 lx · retail sales floor 300 lx.
Visualization
Top-down plan · luminaire grid
Lux level vs application standards

Power Factor Correction

kVAR of capacitor bank required to lift the existing power factor up to the target. Q = P · (tan φ₁ − tan φ₂).

Saudi grid penalty kicks in below PF 0.85. Industrial best practice targets 0.95 unity.

Capacitor Bank Required

110.6kVAR
Compensation needed to reach target PF
Apparent power before correction (S₁)266.7 kVA
Apparent power after correction (S₂)210.5 kVA
Reactive before (Q₁)176.4 kVAR
Reactive after (Q₂)65.7 kVAR
Apparent power saved−56.2 kVA
Bank sizing tip: round up to standard step sizes (12.5, 25, 50, 100 kVAR) and use a multi-step automatic capacitor controller for variable loads. Always include detuning reactors if the site has significant harmonic content.
Visualization
Power triangles · before vs after correction

UPS Sizing

Build the connected load list, set runtime and battery voltage, get the recommended UPS rating in kVA + battery capacity in Ah. Defaults match a typical NLC field-equipment-cabinet (FEC) project.

Connected Devices

Formula: Total W = Σ(qty × W) × cabinets + UPS self × cabinets · KVA = (W × 1+margin)/(PF × 1000) · Battery Ah = (W × backup/60) / V_DC

Recommended UPS

10kVA
Standard size (round-up)
Total connected load5,908 W
With safety margin7,681 W
Required apparent power9.60 kVA
Battery energy needed3,840 Wh
Battery capacity80 Ah @ 48 V
Standard UPS sizes: 1, 2, 3, 5, 6, 10, 15, 20, 30, 40, 60, 80, 100, 120, 160, 200 kVA. The recommendation rounds up to the next standard. For battery, choose the next standard Ah block (e.g. 100 Ah if calc gives 80).
Visualization
Power-flow system diagram
Sizing breakdown vs standard UPS

Solar PV Calculator

Size a solar PV system from daily energy use, estimate generation and savings, and (for off-grid) the battery bank. Defaults tuned for Saudi irradiance.

Array kWp = Daily kWh / (Sun hours × PR), with PR = 1 − losses. Generation = kWp × Sun hours × PR. Off-grid battery kWh = Daily kWh × autonomy / (DoD × efficiency).

Recommended System

6.8kWp
Required array size
Number of panels13
Installed array (from panels)7.15 kWp
Recommended inverter6 kW
Roof area needed34 m²
Daily generation30 kWh
Monthly / yearly900 / 10,950 kWh
Estimated annual savingsSAR 3,285
CO₂ offset / year6,570 kg
Battery bank (off-grid)83 kWh
System cost (est.)SAR 25,000
Simple payback6.5 yrs
Net savings over 25 yrsSAR 95,000
Return on investment380%
Solar cost/kWh (LCOE) vs grid0.11 vs 0.30 SAR/kWh
Worth it.
Note: Planning estimates. Final yield depends on shading, tilt/orientation, temperature derating, and local code.
Visualization
Cumulative savings vs system cost
PV system schematic

EV Charger Calculator

Charging time, the circuit current and recommended breaker & cable for an EV charger, plus total demand for sizing the distribution board.

Time = energy to add / (charger kW × eff). I = P/V (1φ) or P/(√3·V) (3φ). Breaker ≥ 1.25 × I (continuous). Total demand = N × kW × diversity.

Result

5.4h
Charging time (≈ 5h 24m)
Energy to add36 kWh
Charge added per hour11 %/h
Load current (per charger)32.2 A
Recommended breaker40 A
Recommended cable (Cu)6 mm²
Total demand (all chargers)7.4 kW
Total supply current32.2 A
Note: EV charging is a continuous load — size breaker & cable at ≥125%. Add an RCD Type B / RDC-DD per IEC 61851 and confirm DB spare capacity.
Visualization
Charge level & time
Circuit & protection

Transformer Sizing

Size a distribution transformer from connected load, power factor, demand and future-growth factors. Returns the next standard kVA, loading, and LV breaker.

kVA = Load × demand × (1+growth) / PF. FLC = kVA·1000 / (√3·V).

Recommended Transformer

588kVA
Required capacity
Standard transformer630 kVA
Loading at this size93%
Design load400 kW
Full-load current (LV)909 A
Recommended LV breaker1250 A
Note: Keep continuous loading ≤ 80% for headroom. Confirm impedance, vector group, and cooling with the supplier.
Visualization
Loading vs standard rating

LED Retrofit Savings

Compare existing fixtures to LED: annual energy, cost and CO₂ saved, plus simple payback.

kWh/yr = qty × W × hours × days / 1000. Saving = (old − new) energy × tariff.

Annual Savings

39,420kWh/yr
Energy saved
Existing annual64,800 kWh
LED annual25,920 kWh
Energy reduction60%
Annual cost savingSAR 11,664
CO₂ saved / year23,652 kg
Simple payback1.0 yrs
Note: Excludes maintenance/lamp-replacement savings, which shorten payback further.
Visualization
Existing vs LED annual energy

CCTV Storage

Estimate recording storage, total bandwidth and the recommended HDD for an IP camera system.

GB = bitrate(Mbps) × 0.125 × 3600 × hours × days / 1000. H.265 ≈ 0.55 × H.264.

Storage Required

1.9TB
Raw storage
Recommended HDD2 TB
Per-camera bitrate2.2 Mbps
Total bandwidth35.2 Mbps
Per-camera storage0.12 TB
Raw storage1,900 GB
Note: Add RAID redundancy + ~10% OS overhead. Motion-only recording can cut this 40–70%.
Visualization
Storage vs recommended HDD