![]() While normally these currents are small they do occur under normal operation. Ground currents are any current that flows to the ground. On the other hand if you use dedicated grounding wires the currents would follow a well defined path where they could be isolated from other building elements. The steel frame could cause other elements of the building to be exposed to high grounding currents. You want a low impedance electrical ground which I doubt the steel frame would provide. Some times the steel will have a thin layer of rust which is not significant structurally if in an enclosed space but which could impact the resistance. This is aggravated when the steel is painted before installation. I am dubious that bolted connections will provide quality electrical connections. Ground currents could promote corrosion in the steel. It may be possible to apply an interpretation that ignores electronics but that does nobody any good.Īs a structural engineer I would not want the steel frame to be part of the grounding system for several reasons: I suggest that this interpretation, which is informed by an understanding of electronics, would be consistent with the way an electrical engineer would interpret it. The key is how you interpret the language in the NEC. ![]() The choice of which electrode or electrodes to install is at the option of the permit applicant. It is agreed that if you decide to install multiple electrodes they should be bonded. Obviously you will need to install one electrode but it should be clear that you can chose not to install the others. If you do not install a rod electrode it doesn’t exist. A ufer ground does not exist if one is not installed. By the way as a structural engineer I would not want the electrician welding to the holdown bolts. The building steel frame does not exist as an electrode if holdown bolts are not connected to an electrode. This also protects your water pipes from corrosion from grounding currents. In many cases the water company automatically does this. Water pipes can be eliminated as a grounding electrode by placing a plastic pipe element when it goes underground. The key is which of the electrodes exist. Note that it recognizes that only one electrode is possible. ![]() But I doubt the basic intent will have c hanged.Ģ50.50 states that when none of these grounding electrodes exist that one or more shall be installed. Obviously you have changed versions of the NEC Since previously the focus has been on article 250. ![]()
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