Discuss Main Earthing conductor max resistance? in the Electrical Forum area at ElectriciansForums.net

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I know main bonding to water and gas need to be 0.05 ohms

But what about the main earthing conductor?

Does it have a maximum resistance value from MET to the CU?
 
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timhoward

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In practical terms assuming you have a CU very near the MET the resistance should be almost negligible, so if [email protected] is measured it would be well under the max Ze figures of 0.35 (TNCS) and 0.8 (TNS).
It sounds as though this question relates to a particular situation and maybe more details would help.
 

telectrix

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Nope.
GN3 refers to a measurement made between the cable connected to the bonding clamp, and the actual pipe. This reading to be <0.05 ohms. There is no regulation specifically mentioning a maximum resistance of any bonding conductor.
lots of sparks get this wrong. the 0.05 is as you say. absofruitly nothing to do with the resistance of the bonding conductor.
 
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In practical terms assuming you have a CU very near the MET the resistance should be almost negligible, so if [email protected] is measured it would be well under the max Ze figures of 0.35 (TNCS) and 0.8 (TNS).
It sounds as though this question relates to a particular situation and maybe more details would help.
Not situational I have just seen a really long 16mm earthing conductor today on a tncs a few days ago and was just wondering if it had a maximum length
 

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