---
title: "T/F: AAAC vs AAC conductivity"
subject: "Transmission and Distribution System Design"
chapter: 4
key: "semester_8/transmission_and_distribution_system_design:tf-aaac-vs-aac-conductivity"
source: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/tf-aaac-vs-aac-conductivity
site: BCT Engineering
---

# T/F: AAAC vs AAC conductivity

Transmission and Distribution System Design · Chapter 4: Conductor and Support Selection

- Asked in: 2070 Magh, 1+3 marks
- Video: [Types Of Conductor Used in Overhead transmission line. AAC//AAAC//ACSR//ACAR Conductors.](https://www.youtube.com/watch?v=xT5QBtz3FdA) — ଅଶ୍ଵତ୍ଥାମା
- 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/tf-aaac-vs-aac-conductivity
- Whole chapter: https://www.bctengineer.com/md/semester_8/transmission_and_distribution_system_design/chapter-4

## Question

State whether the following statement is TRUE or FALSE. Justify your answer with a brief explanation: The AAAC is superior to the AAC in terms of electrical conductivity.

## Short answer

FALSE. AAC has higher electrical conductivity (≈61% IACS) than AAAC (≈53% IACS) because alloying elements reduce conductivity; AAAC is mechanically stronger but inferior in conductivity.

## Answer

**FALSE.**

- **AAC** (All Aluminium Conductor) is made of pure electrical-grade aluminium (EC grade, 1350). Its conductivity is about **61% IACS**, with resistivity about 0.0283 Ω·mm²/m.
- **AAAC** (All Aluminium Alloy Conductor) uses an Al–Mg–Si alloy (6201). The alloying elements raise its strength but lower its conductivity to about **52.5–53% IACS**, with resistivity about 0.0328 Ω·mm²/m. For the same cross-section, AAAC has about 15% more resistance.

| Property | AAC | AAAC |
|---|---|---|
| Conductivity | Higher (≈61% IACS) | Lower (≈53% IACS) |
| Tensile strength | Low | About twice AAC |
| Sag / span | Large sag, short spans | Smaller sag, longer spans |
| Use | Short urban spans, substations | Distribution and transmission, coastal areas |

AAAC is superior to AAC in **mechanical strength**, hardness and sag performance, not in electrical conductivity.

## Check yourself

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

1. Is the statement 'AAAC is superior to AAC in electrical conductivity' true?
   A. True; alloy improves conductivity
   B. True; AAAC has lower resistance
   C. False; AAC has higher conductivity
   D. False; both have equal conductivity
   Answer: C. AAC is about 61% IACS, AAAC about 53%. (Key point: Verdict)

2. Why is AAAC conductivity lower?
   A. It contains steel core
   B. It has smaller strands
   C. Its aluminium is less pure but denser
   D. Al-Mg-Si alloying raises strength but lowers conductivity
   Answer: D. Alloy elements scatter electrons, raising resistivity to about 0.0328 ohm-mm2/m. (Key point: Why AAAC conducts less)

3. In what is AAAC superior to AAC?
   A. Mechanical strength (about twice) and smaller sag
   B. Electrical conductivity
   C. Lower weight per area
   D. Lower resistance per same cross-section
   Answer: A. That allows longer spans. (Key point: AAAC advantage)

## Related in Transmission and Distribution System Design

- [T/F: ACSR preferred over AAAC](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-acsr-vs-aaac) — Transmission and Distribution System Design, chapter 4
- [T/F: switching surge ratio vs system voltage](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-ssr-system-voltage) — Transmission and Distribution System Design, chapter 3, asked 4×
- [T/F: flashover voltage vs puncture voltage](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-puncture-before-flashover) — Transmission and Distribution System Design, chapter 3, asked 3×
- [T/F: ampacity vs ambient temperature](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-ampacity-ambient-temperature) — Transmission and Distribution System Design, chapter 4, asked 2×
- [T/F: X/R ratio, transmission vs distribution](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-xr-ratio-transmission-distribution) — Transmission and Distribution System Design, chapter 1
- [T/F: economic voltage vs number of circuits](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-economic-voltage-number-circuits) — Transmission and Distribution System Design, chapter 2

## Related in other subjects

- [True/false: derivative controllers always used with others](https://www.bctengineer.com/question.md?key=semester_3%2Fcontrol_systems%3Aderivative-always-with-others) — Control Systems, chapter 7, asked 3×
- [True/false: CT secondary kept open](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machine%3Atf-false-ct-secondary-open) — Electrical Machine, chapter 2
- [True/false: series motor started at no load](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machine%3Atf-dc-series-motor-start-noload) — Electrical Machine, chapter 4
- [True/false: rotor core loss neglected](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machine%3Atf-rotor-core-loss-neglected) — Electrical Machine, chapter 5