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I had an e-mail exchange with an electrician at the local permit office. I told him I am planning on running EMT through my workshop and planned on using the EMT as the grounding wire. He said that is allowed by code, but he "strongly recommended against it" because one bad screw will break the path to ground. Are these connectors that prone to failure?

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  • After the Northridge, CA earthquake (1994) there was a lot of rumors about compression style emt couplings coming apart. After that for a while I saw a lot of people marking the conduit 3/4" from the end so they could see if it walked during install. If you aren't experienced in installing emt that practice might be good even with set screw connectors. – NoSparksPlease Oct 29 '20 at 23:38
  • What type of EMT connectors (press-fit, set-screw, compression) are you using? – ThreePhaseEel Oct 29 '20 at 23:47
  • These would be set-screw type. – tnknepp Oct 30 '20 at 0:29
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No. Code would not allow it if it was a significant risk.

Do be sure to properly tighten all the screws and threaded connections, but they don't just randomly break or "go bad."

Or: Consider that when you use grounding wires, "one bad screw will break the path to ground", too.

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If installed correctly they shouldn't loosen on their own. That said, my inspector too said he wanted to see grounding wires landing on the boxes in addition to the continuous EMT. Apparently, there are at least RUMORS of bad installs causing breaks in the EMT over time. I ran both EMT and the green ground wires, and ended up getting a different inspector for the final that said EMT alone is sufficient but he liked the dual ground paths saying "good, more is better for grounding"... There have probably been a few bad electricians in the past doing shoddy installs and those rumors keep the inspectors weary of using EMT for grounds unfortunately. In my OPINION, I think the continuous EMT ground path is superior to a simple wire tied by a single screw on each end; it provides protection, a fully encasing EMI shield and can probably carry more fault current than a 12 gauge wire.

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