What is an acceptable EGC?

Status
Not open for further replies.
radiopet said:
How on earth did I get involved in these two debates today....lol.....GESSHHH
Click to expand...
My only reason for involvement in these two threads is because I don't believe in "big government" and that is what this is. Building codes are a necessary health and safety function of the governments, but the beyond the enforcement of the minimum legally adopted codes, there should be no other government involvement in the construction process.
 
macmikeman said:
I will volunteer to run a separate ground conductor thru all runs of emt as soon as the poco's of this country run a separate ground conductor with all their service drops....... We could save some cows lives with that one...
Click to expand...


If I didn't run the conduit, I pull an EGC. Can't tell you how many times I've had someone else's work come apart in a pull, or just walked by and tightened couplings on a conduit that was "done".
 
EGC pros and cons

EGC pros and cons

You can verify the acceptability of your EGC ground-fault retune path (per 110.10, 250.4(A)(5) and 250.122. wwwsteelconduit.org is a website where you can download free software to calculate this information simple. "GEMI" developed by the Georgia Institute of Technology (GA-Tech), and as many responded the steel raceway properly installed is superior to an enclosed copper or aluminum EGC.

By adding a optional EGC in the steel raceway you will add approximately 10 to 15 percent to the length that you can run the raceway and it still will provide the low impedance path needed to cause the overcurrent device to trip in the event of a ground fault.

Some engineers require this method because they fear improper installation of the raceway. But if the installer does not make a proper installation of the conduit then who's to say he will properly terminate the enclosed EGC wire. If the raceway is damaged then the enclosed conductors are also not reliable and may present a shock hazard or fail to perform in a fault situation. Therefore, if this happens it must be repaired or else.

Over the years I have opened many boxes to find the green wire cut-off or simply twisted together. 110.14 This is not good.
 
Emt, etc. as EGC

Emt, etc. as EGC

I understand that the NEC does allow the use of approved conduit as the EGC.When an installation is made where device boxes with concentric knock outs are present, installers should be aware that an actual wire EGC IS the only means to ensure a continuous EGC. As an electrical inspector, this minor detail has been the source of frustration in the past. I hope that everyone can agree on this.
 
trusdall84 said:
If I didn't run the conduit, I pull an EGC. Can't tell you how many times I've had someone else's work come apart in a pull, or just walked by and tightened couplings on a conduit that was "done".
Click to expand...

If I didn't run the conduit, I won't be pulling any wire. I work alone. I make sure all joints tight alone also.
 
nysprkdude said:
I understand that the NEC does allow the use of approved conduit as the EGC.When an installation is made where device boxes with concentric knock outs are present, installers should be aware that an actual wire EGC IS the only means to ensure a continuous EGC. As an electrical inspector, this minor detail has been the source of frustration in the past. I hope that everyone can agree on this.
Click to expand...

I hate to dash your hopes. I do not agree with that unless the voltage is above 250 volts. Why are you getting frustrated? 250.97
 
iwire said:
OK, can you show us the part that gives an electrical inspector the authority to fail a job for not following the print? :)
Click to expand...

I think I could take a crack at that one, "Your Honor". I beleive that any job that requires a set of sealed plans to be reviewed and accepted should be followed otherwise the installation has not been reviewed and accepted.

I think that you could use the rule that requires you to furnish the plans before the job starts to fail you for non-compliance. You would not be in non-compliance of the NEC but would be in non-complaince with the rule requiring review and approval.

Are there any rules that specifically allow you to deviate from the approved drawing? Is there a request for a set of generic plans that may or may not be used for the installation of electrical wiring and equipment or are the drawings requested to be specific to this particular installation.
 
who's right?

who's right?

I built a little installation for the paint shop here and have a difference of opinion with the painter who is taking some night courses to become a stationary engineer.

I ran 3/4" EMT surface mounted throughout and did not use any green wire as grounding conductor because NEC 250.118 says that the EMT is acceptable as EGC. It was not complete and a couple of jboxes were open and painter sees there is no green wire, complains to my boss.

There are many new projects being built by engineers and contractors here and all new work has green wire as EGC. I assume this is all because the engineers of the work has specified green wire over and above NEC minimum. I actually asked one of the engineers, who in my opinion has made many wrong calls, if green wire was required by code and he told that that green wire is required.

My boss is not interested in my argument which is: I will gladly pull new green wire, however, green wire is not required. The full text of my argument will follow at the end of this post.

Please either correct me in my misunderstanding or advise me in how to proceed. I mean maybe it is a new rule. I have not had much continuing education!!

Thank you...\
\
////////

As far as the NEC is concerned, the EMT is acceptable as grounding path. Tests prove that it is superior to the copper wire. Question comes up about the integrity of the joints. All joints here are visible and tight. I will be happy to pull a green wire through. I have to move the feed to the water heater anyway. The requirement for the grounding conductor to be an extra wire in the metal pipe is a proposal for the 2011 code. This change has not been implemented. The proposal is only for HVAC equipment.

signed wyreman





The steel raceway properly installed is superior to an enclosed copper or aluminum EGC. By adding a optional EGC in the steel raceway you will add approximately 10 to 15 percent to the length that you can run the raceway and it still will provide the low impedance path needed to cause the overcurrent device to trip in the event of a ground fault. Some engineers require this method because they fear improper installation of the raceway. But if the installer does not make a proper installation of the conduit then who's to say he will properly terminate the enclosed EGC wire. If the raceway is damaged then the enclosed conductors are also not reliable and may present a shock hazard or fail to perform in a fault situation. Therefore, if this happens it must be repaired or else. Over the years I have opened many boxes to find the green wire cut-off or simply twisted together. 110.14 This is not good. http://forums.mikeholt.com/showthread.php?t=116944&highlight=grounding+conductor+conduit+wire&page=7




Can steel conduit/tubing be used as equipment grounding conductors or do you have to use a supplementary conductor? Answer





There is a proposal for the 2011 code. This change has not been implemented.
Section 440.9 Equipment Grounding http://www.ecmag.com/index.cfm?fa=article&articleID=10707
Proposal 11-129 Log No. 2053
(New) This new section adds a requirement for installing a wire-type equipment-grounding conductor with any wiring method used to supply air conditioning and refrigeration equipment. The new text does not clearly indicate whether the requirement applies to the branch circuit only or both the feeder and branch circuit levels of the system. As it is currently worded, the rule would have to apply to both feeders and branch circuits that supply this type of equipment. The substantiation indicates problems with the conduit and tubing types of equipment-grounding conductors that result in ineffective ground-fault current paths when couplings become loose or separate some time after installation. It should be noted that wiring methods should be properly secured and supported in compliance with the NEC and should also not be subject to physical damage or otherwise be suitable for the location. The change results in having to install a wire-type equipment-grounding conductor in all wiring methods supplying air conditioning equipment, even if the conduit, tubing or cable assembly is a suitable equipment-grounding conductor in accordance with 250.118.

CMP-11
Articles: 409, 430, 440, 460, 470,Annex D, Example D8

Proposed Changes
*New* Section 440.9
All circuits installed for air conditioning and refrigeration equipment an equipment grounding conductor in accordance with 250.118(1). Essentially, this means a wire typed equipment grounding conductor must be installed with circuits supplying the equipment. http://www.neca-neis.org/newsletter/report.cfm?articleID=9788




Question; When running feeders in parallel, for example a 400 ampere motor control center, how do you size the ground (EGC) in the raceways? What if you are paralleling MC cable? http://www.steelconduit.org/
Answer; If the parallel raceways are rigid metal conduit, intermediate metal conduit or electrical metallic tubing, an additional EGC is not required.
If you plan to install a copper, aluminum or copper clad aluminum equipment grounding conductor, you would be required to install a 3 AWG copper or a 1 AWG aluminum or copper clad aluminum in each parallel path based on the 400 ampere overcurrent device.
If Type MC cable is used, the manufacturer must be told the overcurrent device rating at the time of the order. This allows the manufacturer to provide the proper size equipment grounding conductor, since MC cable is manufactured based on the maximum overcurrent device permitted to protect a single cable run.
References: 310.4(A) through (E), 300.5(I) Exception 1 and 2, 250.118, 250.122(A) and (F) and Table 250.122


http://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/Grounding-Part-1-of-12~20041005.php
Equipment Grounding (Bonding) Conductor. The low-impedance fault-current path used to connect the noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the grounded (neutral) conductor and equipment grounding (bonding) conductor at service equipment or at the source of a separately derived system.
Author's Comment: The purpose of the equipment grounding (bonding) conductor is to provide the low-impedance fault-current path necessary to facilitate the operation of overcurrent protection devices in order to remove dangerous voltage potentials between conductive parts of building components and electrical systems [250.4(A)(3)].
Author's Comment: According to 250.118, the equipment grounding (bonding) conductor must be one or a combination of the following: Figure 250-02 def 14 250-s118 100.cdr
Conductor. A bare or insulated conductor [250.118(1)]
Rigid Metal Conduit [250.118(2)]
Intermediate Metal Conduit [250.118(3)]
Electrical Metallic Tubing [250.118(4)]
Listed Flexible Metal Conduit as limited by 250.118(5)
Listed Liquidtight Flexible Metal Conduit as limited by 250.118(6)
Listed Liquidtight Flexible Tubing as limited by 250.118(7)
Armor of Type AC Cable [250.118(8)]
Copper metal sheath of Mineral Insulated Cable [250.118(9)]
Metal Clad Cable as limited by 250.118(10) [250.118(10)]
Metallic cable trays as limited by 250.118(11) and 392.7
Cablebus framework as permitted in 370.3 [250.118(12)]
Electrically continuous metal raceways listed for grounding [250.118(13)]
Surface metal raceways listed for grounding [250.118(14)]
Click to expand...
 
Is a green wire required or not is not a yes or no question. In some environments the conduit, if installed properly, can be counted on to handle fault current. Depending on the usage of the area where it is installed, EMT could be pulled apart without damage to the circuit wiring. Rigid pipe has been known to rust so badly as to have a total gap, leaving no continuity. If one of these installations becomes energized with no ability for fault current to get back to the source and you come along to fix it, you might just provide the current path. A green wire here would have saved you.
 
Don S. said:
Is a green wire required or not is not a yes or no question. In some environments the conduit, if installed properly, can be counted on to handle fault current. Depending on the usage of the area where it is installed, EMT could be pulled apart without damage to the circuit wiring. Rigid pipe has been known to rust so badly as to have a total gap, leaving no continuity. If one of these installations becomes energized with no ability for fault current to get back to the source and you come along to fix it, you might just provide the current path. A green wire here would have saved you.
Click to expand...

I seem to remember some crazy poster putting up a picture here at the forum once of a car embedded into the roof of a house....:grin:. I believe the point was that any wiring method could possibly become damaged somehow or another, and therefore the code provides the minimum requirements, not the "what if" requirements.
 
code compliant installation

code compliant installation

...therefore the code provides the minimum requirements
Click to expand...
My question then becomes is this a code compliant installation for a California College in 2010, including NEC, UBC and California Electrical Code.

As far as the NEC is concerned, the EMT is acceptable as grounding path. ... All joints here are visible and tight.
Click to expand...

Is my reasoning is complete with the following arguments for using EMT as EGC?
The steel raceway properly installed is superior to an enclosed copper or aluminum EGC. By adding a optional EGC in the steel raceway you will add approximately 10 to 15 percent to the length that you can run the raceway and it still will provide the low impedance path needed to cause the overcurrent device to trip in the event of a ground fault. Some engineers require this method because they fear improper installation of the raceway.
Click to expand...

There is a proposal for the 2011 code. This change has not been implemented.
Section 440.9 Equipment Grounding http://www.ecmag.com/index.cfm?fa=ar...rticleID=10707
Proposal 11-129 Log No. 2053
(New) This new section adds a requirement for installing a wire-type equipment-grounding conductor with any wiring method used to supply air conditioning and refrigeration equipment.
Click to expand...


Proposed Changes
*New* Section 440.9
All circuits installed for air conditioning and refrigeration equipment an equipment grounding conductor in accordance with 250.118(1). Essentially, this means a wire typed equipment grounding conductor must be installed with circuits supplying the equipment. http://www.neca-neis.org/newsletter/...articleID=9788
Click to expand...


Answer; If the parallel raceways are rigid metal conduit, intermediate metal conduit or electrical metallic tubing, an additional EGC is not required.
Click to expand...

http://www.mikeholt.com/mojonewsarch...2~20041005.php
Equipment Grounding (Bonding) Conductor. The low-impedance fault-current path used to connect the noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the grounded (neutral) conductor and equipment grounding (bonding) conductor at service equipment or at the source of a separately derived system.
Author's Comment: The purpose of the equipment grounding (bonding) conductor is to provide the low-impedance fault-current path necessary to facilitate the operation of overcurrent protection devices in order to remove dangerous voltage potentials between conductive parts of building components and electrical systems [250.4(A)(3)].
Author's Comment: According to 250.118, the equipment grounding (bonding) conductor must be one or a combination of the following: Figure 250-02 def 14 250-s118 100.cdr
Conductor. A bare or insulated conductor [250.118(1)]
Rigid Metal Conduit [250.118(2)]
Intermediate Metal Conduit [250.118(3)]
Click to expand...
 
Last edited:
Status
Not open for further replies.
Top