Dec 19, 2025

What Is AL1 Aluminium Conductor? A Practical Guide to Type AL1 in Overhead Lines

Overhead power transmission and distribution lines operating above 1 kV require conductors that provide reliable electrical performance, stable mechanical properties, and reasonable long-term cost efficiency. In modern power systems, aluminium-based conductors have become the preferred choice, primarily because they offer an excellent balance of low weight, cost-effectiveness, and corrosion resistance under typical outdoor operating conditions.
Within this group, AL1 is one of the fundamental aluminium material grades commonly used for AAC (All-Aluminium Conductors). Under the EN 50182 standard, AL1 defines the aluminium material itself, whereas AAC refers to a category of stranded all-aluminium conductors. In practice, many AAC designs are manufactured using AL1 material; however, the two terms are not interchangeable: AL1 is a material designation, while AAC is a conductor type.

1. Standards Defining AL1 Conductors

AL1-based conductors are defined and governed by several major international standards, including:

Standard	Region	Scope
EN 50182	Europe	Conductors for overhead lines — Round wire concentric lay stranded conductors
IEC 61089	International	Round wire concentric lay overhead electrical stranded conductors
BS EN 50182	UK	Conductors for overhead lines — Round wire concentric lay stranded conductors
DIN 48201-5	Germany	Round aluminium stranded conductors

These standards specify limits for chemical composition. They also define mechanical requirements and stranding tolerances, helping to ensure stable performance under different climatic and installation conditions.

2. What does “AL1” Means Under EN 50182

In the EN naming system:

“AL1” refers to hard-drawn aluminium (about 99.5% minimum).

This material is supplied in a hard-drawn condition. This improves tensile strength but keeps the high conductivity.
Other grades such as AL2–AL6 describe different alloys or tempers. Even so, AL1 remains the most common choice for standard AAC conductors.

3. Construction and Stranding Characteristics

AAC conductors made with AL1 use concentric layers of hard-drawn aluminium wires. Common constructions include:

7-wire
19-wire
37-wire
61-wire

AL1 material offers high conductivity and moderate strength. Because of this, it works well for short to medium spans in distribution overhead lines.

4. Key Technical Characteristics

The following points describe the usual performance of AL1-based AAC conductors.

Electrical Characteristics

High electrical conductivity because of the metal’s purity.
Meets the conductivity requirements in EN 60189.

Thermal Behavior

Many utilities set 75°C as the normal continuous operating temperature for AAC.
Some regions allow higher temperatures. This depends on local engineering rules and ampacity calculation methods.
The final allowed temperature follows utility specifications or national guidelines.

Corrosion Characteristics

Good performance in clean or lightly polluted air.
In strong coastal or corrosive environments, AAAC or other conductor families are usually preferred.

Mechanical Strength

Lower tensile strength than conductors with a steel core.
This limits AL1 usage in long spans or areas with heavy mechanical loading.

5. Application Scenarios and Voltage Levels

AL1-based AAC conductors are widely used in:

Low-voltage (LV) distribution networks where bare conductors are allowed.
Medium-voltage (MV) networks from 10–35 kV.
Short-span overhead lines with moderate mechanical loads.

They can be used in higher-voltage systems. However, the use is limited. Many utilities choose ACSR, AAAC, or newer HTLS conductors when higher mechanical strength or longer spans are required.
In many places, cost-sensitive MV networks continue to choose AAC-AL1 conductors—such as the AL1 overhead conductor series from TDDL cable—because they offer a good mix of conductivity, easy handling, and stable performance in ordinary outdoor conditions.

6. Comparison of Conductors Relative to AAC Using AL1 Material

Parameter	AAC	ACSR	AAAC
Material	Hard-drawn aluminium	Aluminium conductor steel reinforced	Aluminium-magnesium-silicon alloy
Conductivity	Highest	High (slightly reduced by steel core)	High
Mechanical Strength	Low	High	Medium
Weight	Light	Medium	Light
Corrosion Behavior	Good in normal atmospheres	Good in normal atmospheres	Preferred in corrosive areas
Typical Use	Short spans, MV/LV	Long spans, MV/HV/EHV/UHV	Coastal or corrosive zones, medium spans, MV/HV

Each conductor family has its own application field. These fields are shaped by span length, mechanical loads, environmental exposure, and cost considerations.

FAQ

Q: Is AL1 equivalent to AAC?

A: AL1 describes only the aluminium material grade. AAC is the name of the all-aluminium stranded conductor family. Many AAC conductors under EN and ASTM standards are made from AL1/1350-type aluminium, which is why they are often mentioned together, but AL1 and AAC are not the same thing.

Q: Can AL1 be used above 35 kV?

A: Yes, it can. But this depends on span length and mechanical requirements. Many utilities still prefer ACSR, AAAC, or HTLS for higher-voltage systems because these conductors provide greater strength.

Q: Is AL1 identical to ASTM AAC conductors?

A: Both EN AL1 and ASTM AAC use similar high-conductivity aluminium grades in a hard-drawn state. Each standard, however, has its own tolerances for mechanical and dimensional values. This means they are generally treated as comparable but not exactly the same.

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