Conductor Class Updates that Enhance Safety – Key Changes in SEK Handbooks 421 and 444

New Information on Class 5 and Class 6 Conductors

Important changes have been made to the updated SEK Handbook 421 regarding the sizing of cables with class 5 conductors. At the same time, new tables for both class 5 and class 6 conductors have been added to Handbook 444. Since cables with class 5 conductors have a lower current-carrying capacity compared to class 2, these changes mean that the sizing of these cables can no longer be done in the same way.

Safety first!

Longer fuse disconnection times increase the risk of injury and, in the worst case, can be life-threatening. It’s crucial for electricians to account for the new tables and ensure that cables with class 5 conductors are properly sized. Plan for longer disconnection times when using cables with class 5 conductors.

Class 5 Conductors – Flexibility with Safety in Mind

If you prefer using class 5 conductors due to their flexibility and ease of bending, it’s important to consider increasing the cross-sectional size to ensure a safe installation.

Key additions to the cable sizing handbook:

"Calculations of voltage drop and short-circuit currents, which are fundamental to ensuring the correct disconnection time is achieved, are affected by the higher resistance in class 5 conductors. For resistance values, refer to SS-EN 60228."

Key points:

• New tables for class 5 and class 6 conductors (multi-stranded conductors).
• Higher resistance in class 5 conductors means greater voltage drop and longer disconnection times.
• 10% less copper in the cable results in a 10% higher voltage drop.
• Greater energy losses with class 5 conductors compared to class 2 conductors.

Electrify the future safely

If you have any questions or need assistance with the new regulations, feel free to contact us!