Ground in EMT conduit

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finster1

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I would like to know if anyone has ever had an issue with not running ground wires in emt conduit. I am wiring a tanning salon and three of the beds require three phase service, 3 #4's and 6 #6's feed the three rooms in a 1 1/4" conduit . The AHJ thinks I should have run a ground wire to each of the three rooms and I know its not necesary with electrically continuous conduit. This was the maximum amount of conductors I could run in this size conduit and it was a scaffold run which has now been removed and would eat all my profits to add the additional grounds. I know I dont need to use them in the calculation for conduit fill but the price and labor of the scaffolding to do something totally unnecesary seems unfair. What would you guys suggest? Is there anything you can do after the local knocks you done for something that you know is correct.......?

Finster
Licensed Electrical Contractor NJ
 
finster1 said:
What would you guys suggest? Is there anything you can do after the local knocks you done for something that you know is correct.......?J
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Do nothing except ask for a code citation, then continue to do nothing.
 
finster1 said:
I know I dont need to use them in the calculation for conduit fill...
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Check out Chapter 9. Under Table 1, look at note (3)

Equipment grounding or bonding conductors, where installed, shall be included when calculating conduit or tubing fill...
 
finster1 said:
The AHJ thinks I should have run a ground wire to each of the three rooms and I know its not necesary with electrically continuous conduit.
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It really doesn't matter what the EI "thinks"....NJ has not amended the NEC in that regards (358.60)

finster1 said:
I know I dont need to use them in the calculation for conduit fill ......
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HUH?:confused:


EGCs are counted in conductor fill....they are not counted as CCC for derating purposes.

Where did you hear otherwise?

finster1 said:
Is there anything you can do after the local knocks you done for something that you know is correct.......?
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Talk to him first about this...he if cannot accept 358.60 as law, go over his head within that Building Dept. office...if that fails - call Trenton
 
The inspector is obviously mistaken. EMT is permitted as an EGC. He cannot require anything that is outside of the scope of the NEC. As others have said ask for a code reference. I'm curious if the 3-#4's and 6-#6's have taken into account any derating?
 
infinity said:
The inspector is obviously mistaken. EMT is permitted as an EGC. He cannot require anything that is outside of the scope of the NEC. As others have said ask for a code reference. I'm curious if the 3-#4's and 6-#6's have taken into account any derating?
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Unless there's a local amendment.
 
I am aware of the requirements of the NEC............I personally have never installed EMT or any other raceway system without pulling a grounding conductor and wonder why you wouldn't just do it from the get-go.? I would bet that most on this board feel the same.
 
barbeer said:
... wonder why you wouldn't just do it from the get-go.?
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Simply put - it's not required and costs money if you do install a seperate EGC.

There have been studies done that show a properly installed raceway will have a lower impedance (is that the right term or is it resistance) than an EGC brought in with the conductors.

Personally, I prefer the "extra" EGC.

I had a link for this....searching for it now...
 
Another thing to consider a possibility is the instructions with the tanning beds.
I don't know one way or the other but it could require a seperate grounding conductor specifically, something like hot tubs that require all conductors to be #6, even the grounding conductor.
Just a thought.

Paul
 
celtic said:
There have been studies done that show a properly installed raceway will have a lower impedance (is that the right term or is it resistance) than an EGC brought in with the conductors.

Personally, I prefer the "extra" EGC.

I had a link for this....searching for it now...
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Steel Tube Institute data?
 
celtic said:
There have been studies done that show a properly installed raceway will have a lower impedance (is that the right term or is it resistance) than an EGC brought in with the conductors.
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I have read the same thing also. I'm trying to find the data.
 
Michael15956 said:
I have read the same thing also. I'm trying to find the data.
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There is a thread on this forum that has all the info, links and such....

I knew marc was holding out:
#10


Here's another:
#8
 
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Yes, RMC, IMC and EMT are all permitted as an equipment grounding conductor in accordance with NEC? 250.118. It is permitted to add a supplementary equipment grounding conductor sized in accordance with NEC? 250.122.

This is a systems design consideration. If a supplementary equipment grounding conductor is used, it is still very important to comply with NEC? 300.10 and 300.12, since approximately 90% to 95% of the current will flow on the conduit and not in a supplementary conductor.

For information on the equipment grounding capabilities of RMC, IMC and EMT, click here for a link to the section with the results of a research study performed by the Georgia Institute of Technology.
 
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