When performing inspections of various IO-systems at customers sites, we need to clarify if it is allowed to keep the field cable terminal knives open for a prolonged time, eg after decomissioning or post-comissioning of old/ new IS field devices. The duration may be monts, or even years.
Main problem from our viewpoint is that the field wires then are not grounded, and the voltage potential in the wires are free floating.
What are the exact requirements, and what are the accepted practice ref the applicable standard(s)?
How shoule we best communicate the risks around findings of ""open field terminal knives"" for IS-signals?
From NEK EN IEC 60079-14:2024 about Intrinsic safety (Ex i):
8.9.3.4 Unused cores in cables
Each unused core in a cable shall either
• be adequately insulated from earth and from each other at both ends by the use of suitable
terminations; or
• be connected to the earth point used to earth any intrinsically safe circuits in the same cable
but shall be adequately insulated from earth and from each other by the use of suitable
terminations at the other end.