1.5 SWA Current Carrying Capacity Calculator

BS 7671 Table Reference:

\[ I ≈ 19A \text{ for 1.5mm² SWA clipped direct per BS 7671, Table value for SWA cable} \]

Installation Method:

Ambient Temperature:

°C

Cable Grouping:

Insulation Temperature:

Current Carrying Capacity (I):

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1. What is SWA Cable Current Carrying Capacity?

Steel Wire Armoured (SWA) cable current carrying capacity refers to the maximum electric current that a 1.5mm² SWA cable can carry continuously under specified conditions without exceeding its temperature rating. This is determined according to BS 7671 regulations.

2. How Does the Calculator Work?

The calculator uses BS 7671 tables with appropriate correction factors:

\[ I = I_b \times C_a \times C_g \times C_i \]

Where:

\( I_b \) — Base current carrying capacity (19A for 1.5mm² SWA clipped direct)
\( C_a \) — Ambient temperature correction factor
\( C_g \) — Grouping correction factor
\( C_i \) — Installation method correction factor

Explanation: The calculator applies appropriate derating factors based on installation conditions to determine the safe current carrying capacity.

3. Importance of Correct Current Rating

Details: Correct current rating calculation is essential for electrical safety, preventing cable overheating, ensuring system reliability, and complying with BS 7671 regulations.

4. Using the Calculator

Tips: Select the appropriate installation method, enter ambient temperature, specify if cables are grouped, and select the insulation temperature rating. The calculator will apply the relevant correction factors.

5. Frequently Asked Questions (FAQ)

Q1: What is the base current rating for 1.5mm² SWA cable?
A: The base rating is 19A when clipped direct at 30°C ambient temperature with single circuit.

Q2: How does ambient temperature affect current rating?
A: Higher ambient temperatures require derating of the cable (approximately 0.33% per degree above 30°C).

Q3: Why does cable grouping reduce current capacity?
A: Grouped cables have reduced heat dissipation capability, requiring derating to prevent overheating.

Q4: What's the difference between PVC and XLPE insulation?
A: XLPE insulation can withstand higher temperatures (90°C vs 70°C for PVC), allowing higher current ratings.

Q5: Is this calculator suitable for all installation types?
A: This calculator covers common installation methods, but special conditions may require additional considerations per BS 7671.