Grounding conductor requirement?

[Jack Gironda]

As a home inspector, I frequently come across electrical systems with conduit used as the grounding conductor. Obviously, this was permitted in the past, though later the grounding conductor became a requirement. Does anybody know offhand what year the grounding conductor became required? I frequently come across homes built in the 80s and 90s with no grounding conductor which I no was wrong, but I’m still am trying to find definitively when or approximately when it was first required.

 

[Joe.B]

I think it's still permitted, but nobody does it.

 

[Joe.B]

250.118(2)

 

[Joe.B]

no grounding conductor which I no was wrong, but I’m still am trying to find definitively when or approximately when it was first required.

"No grounding conductor" is different than "not grounded". Do you have a copy of the CA Electrical Code, or NEC? If not get one, or access to one, and thoroughly read all of article 250. Then re-read part VI (starting at 250.109) of said article, then when you get to 250.118 you will see and understand why I specifically gave you that reference above.

I know text only communication can leave a false impression of tone and inflection. You could read what I wrote above as condescending or belittling, but please know that's not how it's intended. I am genuinely trying to give you the best direction possible to read the right information and understand the code. Too many people follow the UCL.

Urban Code of Legend

 

[Elect117]

Electrical metal conduit can be used as a EQUIPMENT grounding conductor if you abide by 250.118.

There are instances with in grounding, like grounding electrode conductors and supply side bonding jumpers where they can not be electrical metal conduit. They are required to be bonded to it.


I also wonder if you mean grounded services vs ungrounded services? Like maybe you are referencing older 480V ungrounded services not having a ground/neutral ran from the utility?

 

[tom baker]

EMT as an EGC has a lower impedance than a wire type EGC. Georgia Tech did a research project on this, and it’s used as a basis for the software GEMI which available as a free download, or see Soares book on grounding

 

[augie47]

In 1971 grounding type receptacles were "permitted" and by '78 they were required on 15 and 20 amp circuits
(not sure about 75).
The grounding means was to be included with the circuit and acceptable grounding whether conductor or raceway was similar to today's 250.118

 

[infinity]

Does anybody know offhand what year the grounding conductor became required? I frequently come across homes built in the 80s and 90s with no grounding conductor which I no was wrong,

Actually it is not wrong if there is a metal raceway that qualifies as the EGC then no wire type EGC is required even under the current 2023 NEC.

 

[Speedskater]

EMT as an EGC has a lower impedance than a wire type EGC. Georgia Tech did a research project on this, and it’s used as a basis for the software GEMI which available as a free download, or see Soares book on grounding

Yep, member "GAR" measured 'EMT' on his page.
But exposed 'EMT' can be less reliable than a wire.

far down the page.

BETATRONICS&reg, Electrical photos, communication, Long Cable, High Baud Rate, RS-232, fast, I232, vendor, supplier, manufacturer, industrial

Electrical photos.

www.beta-a2.com

 

[roger]

As a home inspector, I frequently come across electrical systems with conduit used as the grounding conductor. Obviously, this was permitted in the past, though later the grounding conductor became a requirement. Does anybody know offhand what year the grounding conductor became required? I frequently come across homes built in the 80s and 90s with no grounding conductor which I no was wrong, but I’m still am trying to find definitively when or approximately when it was first required.

I don't know where you heard metallic conduit was not permitted as an EGC and ss already stated 250.118 is your reference. The NFPA recognizes metallic conduit is a superior EGC than a wire.

Here is what the authors of NFPA 99 have to say about the reason for both metallic conduit and wire type EGC's


NFPA 99 A 4.3.3.1.3

The performance of the grounding system is made effective through the existence of the green grounding wire, the metal raceway, and all of the other building metal. Measurements have shown that it is the metal raceway and building steel that provide most of the effective grounding path of less than 10 milliohms at the receptacle, including plug to receptacle impedance. The green grounding wire becomes a backup, not a primary path performer.

The fact that a metal raceway (even emt) is a better EGC than a wire conductor is hard for some to swallow, but never the less, it is a fact that it is recognized as such.

Roger

 

[LarryFine]

I rely on EMT and other metallic methods as the EGC all the time, unless specs call for wire.

If they do, then I explore the practicality of non-metallic methods, unless specs call for metal.

I make each conduit connection with the same care I use when making electrical connections.