1. What is an SWA Cable Size Calculator?

Definition: This calculator estimates the required size of Steel Wire Armoured (SWA) cable based on current load and cable ampacity.

Purpose: It helps electricians and engineers determine the appropriate SWA cable size for UK electrical installations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( A \) — Cable cross-sectional area (m²)
• \( I \) — Current load (amps)
• \( \text{ampacity\_swa} \) — Current carrying capacity of SWA cable (A/m²)

Explanation: The current load is divided by the cable's ampacity to determine the minimum required cross-sectional area.

3. Importance of Correct Cable Sizing

Details: Proper cable sizing ensures safety, prevents overheating, and complies with UK wiring regulations (BS 7671).

4. Using the Calculator

Tips: Enter the current load in amps and the SWA cable ampacity (default 20 A/m²). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is SWA cable?
A: Steel Wire Armoured cable is a robust power cable with steel wire protection, commonly used in UK underground and outdoor installations.

Q2: How do I find the ampacity value?
A: Refer to manufacturer specifications or BS 7671 tables based on installation method and environmental conditions.

Q3: What factors affect ampacity?
A: Installation method, ambient temperature, cable grouping, and insulation material all influence ampacity.

Q4: Should I round up the calculated size?
A: Yes, always select the next available standard cable size (e.g., 1.5mm², 2.5mm², 4mm², etc.).

Q5: Does this include voltage drop considerations?
A: No, voltage drop calculations should be performed separately for long cable runs.