using metal trunking as earth

teejay · Feb 28, 2011

Hello can anybody offer some advise. 3 phase lathe being moved in factory workshop . I have to extend 10mm singles in the trunking, upon investigation found the 10mm earthing conductor for the lathe has been taken from the metal trunking. I will probably rewire the earth back to the d.b. as trunking may in time become disconnected therefore losing earth continuity to the lathe, am I doing the right thing or can I rely on the trunking as being a reliable means of earthing.

telectrix · Feb 28, 2011

if the trunking is electrically continuous, i.e. measure resistance ( low ohms ) from DB to point of utilisation. then it's OK to use . however, it's no detriment to add an additional cable cpc, and would possibly reduce your R1+R2,

Guest123 · Feb 28, 2011

Galv trunking is permitted for use as a protective conductor

543.2.2 (vi) refers.

You would need to ensure it's suitability for use though, joints etc.

Deleted member 26818 · Feb 28, 2011

Any earth tags/links would require warning lables.
Much better to my mind to run a separate earth.

somersetsparks · Feb 28, 2011

Yeah just check your readings, I always put bonding links on trunking when I use it for earth, however I don't think theres any requirement to do so, so if they are not in place I would just check all screws on joiners etc.

Tis very common in industrial situation, and perfectly acceptable too, often giving very good readings.