Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, concerning main protective bonding conductor length, is answered by the ECA:
People mention the 0.05, though the only reference is in GN3, and this reads as a test between two points where the bonding connection is, say, structural and not applied to an overhaul length. The regulations only mention the cross sectional area.
Now we are trying to limit the touch voltage, so is there a fundamental calculation that may be used?
Answer: The length of main bonding conductors is not normally something that needs to be considered in most installations.
The maximum touch voltage between extraneous conductive parts for general installations is 50V (some special locations are limited to 25V).
You would have to have an extremely long main bonding conductor to find that kind of voltage drop.
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