09 May What Goes Around Comes Around
In the proposed 2024 IEC 60079-14 Standard (Explosive atmospheres – Part 14: Electrical installations design, selection and erection) there has been an about turn with regard to tear away cables.
In the 2007 and 2013 versions of the Standard, clause 9.3 and 9.3.1 (respectively) is the following statement: “Cables with low tensile strength sheaths (commonly known as ‘easy tear’ cables) shall not be used in hazardous areas unless installed in conduit.”
In 2016 a Corrigendum regarding the 9.3.1 statement was released, “Cables with tensile strength for the outer sheaths of less than 8.5 MPa shall not be used.” There was no technical reason given for this change so it is not surprising that the proposed 2024 version of the Standard includes the following clause (7.4.1 General):
“Cables that have an outer sheath with an initial tensile strength of less than 7 N/mm² (7 MPa) according to the cable manufacturer’s documentation shall be installed with additional mechanical protection, for example installation in conduit.”
What is meant by “tensile strength”? It is referring to the insulation around the conductor.