Question

As per the NBC and IS, a standard lighting sub-circuit should not have more than how many power points like lights, fans, or 5A power outlets?

• A. 10 points
• B. 8 points
• C. 12 points
• D. 15 points

Hint:

Standard Light & Fan Sub-Circuit Thresholds: \[ \text{Maximum Points} = 10 \quad \text{AND} \quad \text{Maximum Connected Load} = 800\text{ W} \]

Answer 1

The Correct Option is A

Concept: To prevent electrical overloads, overheating, and fire risks in internal structural wiring, the National Building Code (NBC) of India and Indian Standards (IS:732) enforce strict electrical safety limits. These codes regulate the maximum number of connected fixtures and the total electrical load allowed on a single sub-circuit.

Step 1: Analyzing code requirements for light and fan sub-circuits.
Indian code regulations separate consumer circuits into low-power lighting lines and high-power appliance lines:
• For a standard lighting and fan sub-circuit (handling light bulbs, ceiling fans, and low-draw 5A socket outlets), the circuit must satisfy two simultaneous threshold parameters:
• The total connected load must not exceed $800\text{ W}$.
• The total number of connected load points must not exceed 10 points.
• If either of these limits is crossed, the system must be split into a separate sub-circuit controlled by its own miniature circuit breaker (MCB) at the distribution board.

Step 2: Comparing with power sub-circuits.
To avoid confusion, let us examine the rules for a power sub-circuit (designed for heavy appliances like air conditioners, geysers, or refrigerators using 15A/16A outlets):
• A power sub-circuit is limited to a maximum of 2 points.
• The maximum load limit for a power sub-circuit is $3000\text{ W}$. Since this question asks specifically for the maximum number of structural points on a standard lighting sub-circuit, the answer is 10 points.