AS/NZS61439 – What you need to know about “Strength of Material Parts”?

17 August 2022

AS/NZS61439 – What you need to know about “Strength of Material Parts”?

AS/NZS 61439 requires the verification of the strength of material parts.  All these characteristics are to ensure your switchboards meet the required service life.

There are 8 characteristics within “Strength of Material parts” that need to be verified by test or by assessment.

This is a video of our Demcon modular switchboard busbar supports which has been successfully glow wire tested to 960oC.   As part of the requirements if the sample catches alight it must self-extinguish within 30 seconds. You will also notice the tissue paper underneath, which must not ignite from any droplets from the sample. 

We’ve also listed out the 8 characteristics below with some helpful points (Cheat Sheets) for designers!

STRENGTH OF MATERIAL PARTS
TABLE D.1 CHARACTERISTIC 1
Characteristic to be verified
Verified by
Helpful points for designers
Resistance to corrosion (10.2.2) Test Outdoor switchboards (made of ferrous materials) and outer hardware – Tested to Severity Test B (10.2.2.3)

Before Test (shiny)

After Test (salty)

Indoor switchboards (made of ferrous materials), and internal hardware of indoor and outdoor switchboards tested to Severity Test A (10.2.2.2).

Aluminium enclosures are exempt from test.   Note: “In all cases hinges, locks and fastenings shall also be tested…” ferrous-based or not!
Thermal stability (10.2.3.1) Test Applies only to switchboards made of insulating materials
Resistance to abnormal heat and fire due to internal electric effects (10.2.3.2) Test, Assess Busbar supports and cleats glow wire tested to 960oC, all other parts inside a switchboard including earth supports tested to 650oC

 

For clarity, Assess means the support supplier can do the testing and give you a copy of the test report. This allows designers to swap out supports for other successfully tested supports (although make sure they are suitable for the short circuit withstand rating)

 

Switchgear built to AS/NZS 60947 series has been glow wire tested.
Resistance to ultra-violet (UV) radiation (10.2.4) Test, Assess Powder and paint coatings on switchboards, must be adhesion tested with cutting and weather tested for 500 hours to ISO 4892-2 Method A, Cycle 1.

 

Note: Assess means the paint/ powder coat supplier can do the testing and give you a copy of the test report.  However, the same coating procedure must be followed by the switchboard/sheetmetal manufacturer.

After testing – note the cross cuts from the adhesion test
Lifting (10.2.5) Test To determine maximum size & weight of switchboard shipping section.  Must be tested at 1.25 x the maximum weight.
Mechanical impact (10.2.6) Test Applies to AS61439.3 only (for example residential, commercial distribution boards operated by ordinary persons).
Marking (10.2.7) Test Durability and legibility of markings – rub tested by hand using water and petroleum for 15 seconds each.