Скачать или смотреть 84 Cable Size Calculator Tool How to Choose the Right Cable Size

Choosing the right cable size is essential for safety, efficiency, and compliance with electrical standards. An incorrectly sized cable can cause overheating, voltage drop, or even fire hazards.

⚙️ Steps to Choose the Right Cable Size

1. Determine the Load Current (Amps)

Use the formula:

Current (I)=Power (W)Voltage (V)×Power Factor (pf)\text{Current (I)} = \frac{\text{Power (W)}}{\text{Voltage (V)} \times \text{Power Factor (pf)}}

For example, a 2000W load on a 230V single-phase circuit:

I=2000230×0.95≈9.2 AmpsI = \frac{2000}{230 \times 0.95} \approx 9.2 \text{ Amps}

2. Check the Voltage Drop

Voltage drop occurs over long cable runs.

Most standards allow a max 3–5% voltage drop.

Use a voltage drop calculator or formula:

Vd=2×L×I×R1000V_d = \frac{2 \times L \times I \times R}{1000}

Where:

LL = Length (one-way) in meters

RR = Resistance (Ω/km) of the cable material

Choose a larger cable if voltage drop is too high.

3. Consider the Cable Installation Conditions

Factors affecting current-carrying capacity:

Ambient temperature

Cable grouping (bundled or not)

Installation method (in conduit, underground, free air)

Use derating factors to adjust the ampacity.

4. Check Short-Circuit Rating

Ensure the cable can withstand potential short-circuit current for the protection device’s clearing time.

5. Match with Protective Devices

The cable’s current rating should be equal to or greater than the rating of the breaker or fuse protecting it.

6. Refer to Standards

Follow local electrical codes like:

NEC (USA)

IEC or BS7671 (UK/EU)

IS/IE Rules (India)

Use standard cable sizing charts or software.

? Or Use a Cable Size Calculator

Input:

Load current

Length of cable

Voltage

Phase (Single/Three)

Permissible voltage drop

Installation type

The tool gives:

Recommended cable cross-sectional area (mm² or AWG)

Voltage drop

Current-carrying capacity

✅ Example:

For a 230V single-phase, 10A load, running 30 meters in a conduit, you might need:

1.5 mm² for short distances

2.5 mm² or larger to minimize voltage drop over long runs