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We just bought a Chicago-area house and found that there's no ground wire in some of the recently re-wired areas. I thought that the national electrical code requires a ground wire for new construction and remodels, as opposed to relying on the steel conduit as ground. Is this correct?

  • I'm not sure exactly what you're asking. If installed properly, metallic conduit and tubing can still be used as an equipment grounding conductor (EGC) (as of NEC 2014). As for when equipment grounding conductors started to be required, I'm not sure. If you know when the remodel happened, somebody might be able to tell you if it was required at that time. – Tester101 Sep 22 '15 at 20:13
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Conduit (RMC, IMC or EMT) is an NEC-accepted ground path. So, if the wires are in steel conduit, no OTHER ground wire is required.

If that gives you concerns, you might find this link reporting research into the effectiveness of conduit as a ground relieves them.

https://www.nema.org/Technical/Documents/Steel%20Conduit%20and%20EMT-Proven%20to%20Meet%20the%20NEC%20Reg.pdf

  • @Tester101 I do not see an "exclusion for residential use" in the code. That would surely be there if the NFPA agreed with your contention. While conduit in houses may not be overly common outside of Chicago, it's still a code-compliant grounding conductor if it is used. – Ecnerwal Sep 22 '15 at 21:12
  • I called my local inspector; it ends up that grounding wire is not required, and using steel conduit to carry ground is perfectly acceptable. I'll edit the question. – glenviewjeff Sep 23 '15 at 0:43
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National Electrical Code does allow metallic conduit and tubing to be used as an equipment grounding conductor, as long as it's installed properly.

However, before using it as such in an existing installation, you should verify that it provides an adequate continuous path to ground.

National Electrical Code 2014

Chapter 3 Wiring Methods

Article 342 Intermediate Metal Conduit: Type IMC

342.60 Grounding. IMC shall be permitted as an equipment grounding conductor.

Article 344 Rigid Metal Conduit: Type RMC

344.60 Grounding. RMC shall be permitted as an equipment grounding conductor.

Article 348 Flexible Metal Conduit: Type FMC

348.60 Grounding and Bonding. If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an equipment grounding conductor shall be installed.

Where flexibility is not required after installation, FMC shall be permitted to be used as an equipment grounding conductor when installed in accordance with 250.118(5).

Where required or installed, equipment grounding conductors shall be installed in accordance with 250.134(B).

Where required or installed, equipment bonding jumpers shall be installed in accordance with 250.102.

Article 350 Liquidtight Flexible Metal Conduit: Type LFMC

350.60 Grounding. Grounding and bonding for LFMC shall be installed in accordance with 350.60(A) and (B).

(A) If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an equipment grounding conductor shall be installed.

Where flexibility is not required after installation, LFMC shall be permitted to be used as an equipment grounding conductor when installed in accordance with 250.118(6).

Where required or installed, equipment grounding conductors shall be installed in accordance with 250.134(B).

Where required or installed, equipment bonding jumpers shall be installed in accordance with 250.102.

(B) Where Air Conditioning or Refrigerating Equipment is installed outdoors, an equipment grounding conductor per 250.118(1) shall be provided within the raceway and shall be sized per 250.122.

Article 358 Electrical Metallic Tubing: Type EMT

358.60 Grounding. Grounding and bonding EMT shall be installed in accordance with 358.60(A) and (B).

(A) EMT shall be permitted as an equipment grounding conductor

(B) Where Air Conditioning or Refrigerating Equipment is installed outdoors, an equipment grounding conductor per 250.118(1) shall be provided within the raceway and shall be sized per 250.122.

Article 360 Flexible Metallic Tubing: Type FMT

360.60 Grounding. FMT shall be permitted as an equipment grounding conductor where installed in accordance with 250.118(7).

  • Guessing that the 358.60(B) grounding conductor is required due to expected corrosion. – Technophile Nov 14 '17 at 2:25

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