---
title: "Define responsibility factor"
subject: "Transmission and Distribution System Design"
chapter: 6
key: "semester_8/transmission_and_distribution_system_design:define-responsibility-factor"
source: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/define-responsibility-factor
site: BCT Engineering
---

# Define responsibility factor

Transmission and Distribution System Design · Chapter 6: Electrical Load Characteristics and Load Forecast

- Asked in: 2069 Bhadra (old course), 3 marks; 2067 Chaitra (old course), 2 marks (asked 2 times)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/define-responsibility-factor
- Whole chapter: https://www.bctengineer.com/md/semester_8/transmission_and_distribution_system_design/chapter-6

## Question

Define responsibility factor with respect to distribution consumer characteristics and discuss its significance on the design of distribution system.

## Short answer

Responsibility factor is a consumer class’s load at the system peak divided by its own maximum demand. It weights class peaks to obtain the actual system peak, guiding equipment sizing and tariff designs that target the responsible class.

## Answer

**Responsibility factor** (also called contribution factor) of a consumer or consumer class is the ratio of its load at the time of the system (or group) peak to its own maximum demand:

$$
\text{Responsibility factor } c_i = \frac{\text{Load of consumer } i \text{ at time of system peak}}{\text{Maximum demand of consumer } i} \le 1
$$

For example, a commercial class with a 10 kW peak at noon that draws only 5 kW at the evening system peak has a responsibility factor of 0.5.

The system peak is then $P_{system} = \sum c_i P_{max,i}$, and the coincidence factor of the group is $\sum c_i P_{max,i} / \sum P_{max,i}$.

**Significance in distribution design:**

- At a load centre with several consumer classes (domestic, commercial, industrial), the class peaks occur at different hours. The load centre peak is the sum of each class peak weighted by its responsibility factor, not their plain sum.
- It is the key input for sizing distribution transformers and feeders in load forecasting (e.g. "5th year contribution factor to peak").
- It identifies which class is responsible for the peak; tariffs (time-of-day pricing) and demand-side measures can then target that class.
- Using correct factors avoids oversizing equipment and reduces capital cost and no-load losses.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Responsibility (contribution) factor of a consumer is:
   A. Its load at the time of system peak divided by its own maximum demand
   B. Its average load divided by its peak
   C. System peak divided by its demand
   D. Its energy divided by total energy
   Answer: A. It compares what the consumer draws at system peak with its own maximum demand, and is at most 1. (Key point: Definition)

2. A commercial class has a 10 kW noon peak and draws 5 kW at the evening system peak. Its responsibility factor is:
   A. 2
   B. 0.5
   C. 0.1
   D. 1
   Answer: B. 5/10 = 0.5. (Key point: Example)

3. How is it used in design?
   A. System peak = sum of (c_i x class peak), not the plain sum, which avoids oversizing and shows which class drives the peak
   B. System peak = sum of class peaks
   C. It sets the LT voltage
   D. It gives the power factor
   Answer: A. Class peaks occur at different hours, so each is weighted by its factor. (Key point: Design significance)

## Close variants set in other exams

- [Define coincidence factor](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Adefine-coincidence-factor) — Transmission and Distribution System Design, chapter 6, asked 2×
- [Define coverage factor](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Adefine-coverage-factor) — Transmission and Distribution System Design, chapter 6, asked 2×
- [Define loss of load factor](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Adefine-loss-of-load-factor) — Transmission and Distribution System Design, chapter 6, asked 2×

## Related in Transmission and Distribution System Design

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- [5th year peak load from consumer survey](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Afifth-year-peak-load-survey) — Transmission and Distribution System Design, chapter 6, asked 7×
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- [Distribution system used in INPS](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Ainps-distribution-system-type) — Transmission and Distribution System Design, chapter 5
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