Technical Update for Solar Designers and Installers
The selection and sizing of cables are fundamental to the safety and performance of any electrical installation. In the solar industry, where solar cable sizing across Australian installations must account for high currents and harsh environmental conditions, adhering to the latest standards is not just a regulatory requirement, it is a critical safety measure.
With the release of AS/NZS 3008.1.1:2025, the industry sees a major shift in how cable sizing is approached. This update, which becomes mandatory across Australia on June 19, 2026, introduces a more streamlined structure, updated terminology, and specific provisions for DC systems that were previously absent.
The Purpose of AS/NZS 3008.1.1
At its core, AS/NZS 3008.1.1 provides the methodology for selecting the correct cable size by evaluating several key constraints:
- Current-Carrying Capacity (CCC): Ensuring cables can handle the intended load without overheating.
- Overcurrent Protection: Coordinating cable size with protective devices.
- Voltage Drop/Rise: Maintaining efficiency and ensuring inverter compliance.
- Short-Circuit Current: Ensuring the cable can withstand fault conditions.
Quick Comparison: AS/NZS 3008:2017 vs 3008.1.1:2025
| Parameter | AS/NZS 3008:2017 Approach | AS/NZS 3008.1.1:2025 Update | Practical Impact |
|---|---|---|---|
| DC Cable CCC | Derived from AC values using 1.155 factor | Dedicated DC tables (3.21 & 3.22) | Faster and more accurate DC cable sizing |
| Voltage Drop | AC tables adapted for DC | Dedicated DC voltage drop table (4.16) | Simplifies DC calculations |
| Terminology | “Derating Factor” | “Correction Factor (CF)” | Aligns with modern terminology |
| Flexible cables | Separate considerations | Treated same as stranded conductors | Simplifies selection |
| HF-110 cables | Higher CCC assumptions | CCC slightly reduced | Some systems may require larger cable size |
Major Changes for the Solar Industry
1. Restructured Tables for Better Accessibility
One of the most user-friendly updates is the complete restructuring of the tables. Previously, navigating the numerous tables for different installation conditions could be cumbersome. In the 2025 edition, tables are organized by chapter, and many have been consolidated onto single pages to reduce the need for constant page-flipping. Furthermore, several values have been refined for greater accuracy based on updated thermal modeling.
2. Dedicated DC Cable Tables
Historically, solar designers had to adapt AC cable tables for DC applications, often applying a 1.155 conversion factor to approximate values. The 2025 standard simplifies this by introducing dedicated tables for DC cables:
- DC cable current-carrying capacity (CCC) values are now found in Tables 3.21 and 3.22, replacing the previous workaround of adapting AC tables (see our previous guide on DC cable sizing using AS/NZS 3008).
- Voltage Drop for DC: Now found in Table 4.16.
While the new DC values are technically more accurate, you will find they remain quite similar to the previously derived values when the conversion factor was used correctly. For more complex DC circuit scenarios, such as underground cables or multi-core configurations, our guide on specialised cable sizing using AS/NZS 3008.1.1 explores where IEC 60287 may be the more appropriate methodology
Key Change
AS/NZS 3008.1.1:2025 introduces dedicated DC cable tables (Tables 3.21 and 3.22), eliminating the need to approximate DC values using the 1.155 conversion factor previously applied to AC tables.
3. Updated Terminology: “Correction Factors”
The industry-standard term “derating factor” has been officially replaced with Correction Factor (CF). This change aligns the standard with other international benchmarks and modern electrical terminology. Understanding how to apply a correction factor to cable sizing is essential when installations differ from standard ‘free air’ or ‘underground’ benchmarks, such as high ambient temperatures or cables bunched in conduits
Terminology Update
The term Derating Factor has been replaced with Correction Factor (CF) in the 2025 edition, aligning the standard with modern international electrical terminology.
4. Flexible Cables and Stranded Conductors
In a significant simplification, flexible cables have been removed from the specific CCC tables. The standard now assumes that flexible cables have the same current-carrying capacity as standard stranded conductors, streamlining the selection process for installers who frequently use flexible leads for inverter connections.
5. Adjustments for HF-110 Cables
Solar installers using HF-110 cables (Halogen-Free, 110°C rated) in photovoltaic systems should take note: there are significant changes to both the CCC and voltage drop values for these cables in the 2025 edition. Generally, the CCC for HF-110 has been slightly reduced, meaning some previous designs may require larger cross-sectional areas to remain compliant.
Important Design Consideration
The current-carrying capacity values for HF-110 cables have been slightly reduced in the 2025 edition, which may require designers to reassess cable sizing in some existing system designs.
Due to the restructuring of AS/NZS 3008.1.1:2025, several tables have been renumbered or reorganized. The following comparison highlights where commonly used tables from the 2017 edition can now be found in the 2025 standard.
Table Mapping Between AS/NZS 3008:2017 and AS/NZS 3008.1.1:2025
Table 1 – Current-Carrying Capacity Tables
| Cable Type | System | 2017 Table | 2025 Table |
|---|---|---|---|
| PVC | DC | Table 4 | Table 3.21 |
| XLPE | DC | Table 5 | Table 3.22 |
| PVC | AC Single Phase | Table 10 | Table 3.15 |
| XLPE | AC Single Phase | Table 11 | Table 3.16 |
| PVC | AC Three Phase | Table 13 | Table 3.18 |
| XLPE | AC Three Phase | Table 14 | Table 3.19 |
Table 2 – Voltage Drop / Voltage Rise Tables
| Parameter | System | 2017 Table | 2025 Table | Notes |
|---|---|---|---|---|
| Voltage Rise | DC | Not used | Table 4.16 | New DC table |
| Voltage Rise | AC Single Phase | Table 42 | Table 4.17(B) | Converted to single phase |
| Voltage Rise | AC Three Phase | Table 42 | Table 4.17(B) | Multicore cable |
Table 3 – Short Circuit Constants
| Parameter | 2017 Table | 2025 Table |
|---|---|---|
| Constant K values | Table 52 | Table 5.1 |
| Temperature limits for insulating materials | Table 53 | Table 5.2 |
Table 4 – New addition in AS/NZS 3008.1.1:2025
| Parameter | System | 2017 Table | 2025 Table | Notes |
|---|---|---|---|---|
| Voltage Rise | DC | Not used | Table 4.16 | New DC provision |
Note: Table numbers referenced above correspond to commonly used design tables within AS/NZS 3008:2017 and AS/NZS 3008.1.1:2025. Designers should verify installation conditions and correction factors as required by the relevant sections of the standard.
Moving Toward 2025 Compliance
The transition to the 2025 standard marks a step forward in aligning cable selection with the high-voltage capabilities now permitted in residential systems (the “1000V rule” introduced in AS/NZS 4777.1:2024).
Preparing for the 2025 Standard Transition
As the June 19, 2026 implementation date approaches, solar professionals should begin familiarising themselves with the updated tables and terminology introduced in Chapters 3 and 4 of the new standard. As the industry transitions to the 2025 edition, design tools, workflows, and training will gradually align with the revised methodology for cable selection. Staying ahead of the AS/NZS 3008 2025 update now means less disruption to workflows and design tools when the mandatory date arrives.
To support this transition, a Continuing Professional Development (CPD) course is currently being developed that will highlight the key updates and practical implications of the standard for the solar industry and to adhere to Solar Accreditation Australia’s CPD requirements. By staying informed and preparing early, designers and installers can ensure that the solar systems of tomorrow remain safe, compliant, and efficient.
Want to learn more about GSES’s training and consultancy work? Get in touch with our team.