Conduit accepted as ground.

[Mark Horner]

You can certainly put in a proposal to require a wire type EGC in a metal raceway, your proposal (or PI) would be for the 2026 NEC, plenty of time to gather documentation. Past proposals to require wire type EGC have been rejected with the comment that properly installed RMC, EMT, IMC is an acceptable EGC, Keep in mind who is on the CMP, take a look at CMP No. 8.

thanks for your answer,so in theory if a service panel or a piece of equipment is installed and fed with conduit then the equipment grounding conductor chart is not needed.

 

[infinity]

thanks for your answer,so in theory if a service panel or a piece of equipment is installed and fed with conduit then the equipment grounding conductor chart is not needed.

Take a look at 250.118, that tells you when a raceway can be used as an EGC. If it qualifies then yes you do not need to install a wire type EGC. A service panel does not use an EGC on the line side anyway so that point is moot.

 

[AC\DC]

I could possible see needing it for EMT in case a coupling or connector pops out, though it should not.If RMC/IMC is that messed up to bust a coupling then you got bigger problems with the open conductor just floating there, at least how I see it.

 

[Mark Horner]

Take a look at 250.118, that tells you when a raceway can be used as an EGC. If it qualifies then yes you do not need to install a wire type EGC. A service panel does not use an EGC on the line side anyway so that point is moot.

In a install in a commercial or a industrial setting theres doesnt seem at all logical nor would i ever consider not pulling a properly sized ground for the sake of safety or at the lowest thinking of saving a dollar ,at least you would have a redundency.

 

[Mark Horner]

I could possible see needing it for EMT in case a coupling or connector pops out, though it should not.If RMC/IMC is that messed up to bust a coupling then you got bigger problems with the open conductor just floating there, at least how I see it.

galvanized conduit rust and corrodes fairly quickly,without the use of noalox it happens even quicker.

 

[tom baker]

galvanized conduit rust and corrodes fairly quickly,without the use of noalox it happens even quicker.

Corrosion on RMC depends on soil type. Around here RMC can last for 50+ years. Corrosive environments are addressed in 344.10 Uses Permitted, (B) Corrosive Environments.
Please explain the use of Noalox for RMC and how its used?

 

[ActionDave]

In a install in a commercial or a industrial setting theres doesnt seem at all logical nor would i ever consider not pulling a properly sized ground for the sake of safety or at the lowest thinking of saving a dollar ,at least you would have a redundency.

Let's see, you've got a metal conduit tied to metal framing with metal straps held in place with metal fasteners I think it would be a bigger problem to try and isolate a piece of emt or other metal conduit than it would be to rely on it as an effective equipment ground.

While we are at it let's consider that one in a million special piece of emt that is somehow separated from the rest of the run and isolated from all the metal in the building, and let's make sure that a green wire is pulled in with all the hot conductors. With the power turned off let's scrape a big chunk of insulation off one of the hot conductors and just for fun lets wrap that bare, hot wire around the end of the conduit so there is no doubt that the isolated piece of emt is energized when we turn the power back on. Now let's go turn the power back on and see how much safer it is to touch that piece of energized emt that has a green wire pulled in it.

 

[infinity]

In a install in a commercial or a industrial setting theres doesnt seem at all logical nor would i ever consider not pulling a properly sized ground for the sake of safety or at the lowest thinking of saving a dollar ,at least you would have a redundency.

We install EGC's when the customer is paying for them. If they want to save money and do not specify wire type EGC's they don't get them based on the aforementioned section that allows certain metallic raceways to serve as the EGC. The NEC is a minimum standard there is nothing the prohibits one from exceeding it.

 

[electrofelon]

In a install in a commercial or a industrial setting theres doesnt seem at all logical nor would i ever consider not pulling a properly sized ground for the sake of safety or at the lowest thinking of saving a dollar ,at least you would have a redundency.

I mostly do design-build light to mid sized commercial work and pretty much never pull a wire EGC. Much of this is T&M, and I would actually make more because of material markup if I pulled a green wire, but it seems like a waste to me and I wouldn't do it if I was writing the check so I don't do it for my customer.

This whole resistance to using the conduit as an EGC is a relatively new phenomenon that as far as I can tell isn't based on any history of problems whatsoever. I actually think it is a dangerous trend - this obsession with grounding - because it seems to be all anyone cares about and other aspects of an electrical system that are as, or even more important are skipped over.

Personally, I am more comfortable with a conduit system being an EGC than a green wire due to the high prevalence of poor wire nut connections I come across.

 

[SSDriver]

I agree with others that metallic raceways is perfectly fine. Around here, by the time the conduit is rusted away the wires are gone as well or the enclosure is destroyed and everything is being replaced anyways. I personally haven't see any issues. I have seen way more bad wire nut connections than poor conduit connections. At least you can see the conduit issues on the outside(most of the time).

 

[paulengr]

NEC says that conduit can be used as the ground,I`m not sure sure how this could be at all acceptable due to the vulnerability of the connection that is easily susceptible to being disrupted,can someone explain to me about this?

The resistance of steel is less than copper and aluminum but the area is massively higher. Sure oxidation might be a problem to some degree but iron oxide is a semiconductor. So during faults it is better than a copper ground. The steel tubing institute did a bunch of tests and computer models and published it for free on their web site.

X/R is a consideration which they cover. Hence with nonlinear power like VFDs a copper ground is requires but for fault purposes conduit is the way to go.

 

[paulengr]

corrosion between couplings or connectors or even loose locknuts

As metals corrode they expand. They have to because the oxygen (or sulfur) atoms have to go somewhere. This tightens everythjng up with surface rust. But just like copper wiring if properly tightened the bulk of the connection is metal to metal and gas tight:

When you install conduit nuts make sure to install them with the sharp tooth side facing the metal surface. Tighten with a conduit wrench or the traditional way with a hammer and a punch or screwdriver, not lineman’s. Those don’t have enough force to do anything. If you don’t the locknut won’t bite through the paint and does nothing at all. Inspectors need to look at the paint or metal surface between the conduit teeth. If they don’t see scratches where it dug in, it was never tightened. And it can’t possibly come loose. The only failures I see are crushing and bending from say fork trucks, and knockout rings coming apart.

 

[paulengr]

In a install in a commercial or a industrial setting theres doesnt seem at all logical nor would i ever consider not pulling a properly sized ground for the sake of safety or at the lowest thinking of saving a dollar ,at least you would have a redundency.

The hospital Code requires two redundant grounds. So it almost mandates both.

 

[gadfly56]

I could possible see needing it for EMT in case a coupling or connector pops out, though it should not.If RMC/IMC is that messed up to bust a coupling then you got bigger problems with the open conductor just floating there, at least how I see it.

I always bottomed out the screw on screwed connectors. Doesn't everyone do that? No way was that connector popping loose, high vibration environment notwithstanding.

 

[roger]

The hospital Code requires two redundant grounds. So it almost mandates both.

It does mandate both, read 517.13(A) & (B) Commentary in appendix A of NFPA 99 points out that the metallic raceway is the primary (better) EGC and the wire is secondary.

Roger

 

[electrofelon]

I always bottomed out the screw on screwed connectors. Doesn't everyone do that? No way was that connector popping loose, high vibration environment notwithstanding.

I think dia cast connectors might be designed that way, but it doesn't appear that most steel connectors are.

 

[don_resqcapt19]

Circuit protective conductor, earth or ground wire. I see pics on forums where its run separate at times.

If by CPC you mean EGC, running separate from the circuit conductors is not permitted by the NEC except for some very rare cases.

 

[mbrooke]

If by CPC you mean EGC, running separate from the circuit conductors is not permitted by the NEC except for some very rare cases.

Yup. But I see the practice in UK pictures. I disagree in doing it since the reactance goes up.

 

[hbiss]

I think dia cast connectors might be designed that way, but it doesn't appear that most steel connectors are.

I've stripped out or broken the threaded boss off of diecast fittings by over torquing the set screws. I probably should say that the reason I don't worry about the ground continuity of EMT is because I always specify steel fittings.

Diecast set screw fittings have their place but I don't prefer them.

-Hal

 

[Mark Horner]

The hospital Code requires two redundant grounds. So it almost mandates both.

Thank you,makes total sense.