Unique solution to an expensive situation.

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Re-idenify the EGC as a neutral and move on. If this panel had no EGC and you ran a circuit from it would you be testing the continuity of the EMT?
 
iwire said:
Really?

I see he posted one test result.
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I believe that was all the testing he needed to do to rule his idea out. ;)

He would now have to do some searching to find the problem.

Roger
 
With that high a resistance, the original plan is dead in the water.
It seems there are three options: (a) install a neutral by adding a wire or re-pulling the feeder (assuming conduit fill will allow); (b) add a 120v transformer, or (c) male the necessary repairs to the conduit run to make it an acceptable ground path.
Without knowing the details about the conduit run, and not knowing the proposed load, we would simply be guessing at the best solution.
 
iwire said:
You are assuming he lifted both ends of the EGC, I do not see that he has said that.
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And if he didn't he should have clarrified what that was what he was doing, it would have been a big help.

Roger
 
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iwire said:
EMT is an acceptable EGC, if I could verify it is continuous I would use it as the EGC and not make a mountain out of a mole hill.
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Bob ,he is looking at 200 feet. That is 20 connections and 40 screws. Take a look at what the load is. Your right it is legal but if one screw fails we might have a death.
Then after investigation they find out he removed the gec.
The original installer put it in for a reason, either specs or to insure a good ground.
In FL most everyone runs a grounding wire, perhaps things are differant up there.
To verify the run means he will need to check every screw. If he can do that he could likely add a ground wire on outside.
Nothing to be made up BOB they are all facts. Maybe your the one with with a beer can.
 
iwire said:
And you know that he disconnected both ends of the EGC how? (Or should I say How????????) :grin:
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I am assuming he is an electrician, he has a megger and that leads one to believe that he has the sense to isolate the EGC. But you know the old "you know what happens when you ASSUME"

How would you have tested the electrical continuity of the EMT if you lifted both ends of the EGC first? :)
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The best solution would be a visual first, testing ("assuming" a commercial establishment), testing will prove nothing if there are metal ducts, piping and metal studs, concrete with rebar, metal trusses and/or a drop ceiling, testing the EMT will do little to prove the EMT is sufficient.
 
If the conduit is continuous, there is no problem using it as an equipment ground.
Normally the only time we (area of conduit only Chicago) use a redundant ground, is when it's required by code or it is a spec required by an engineer, which is not uncommon. Chances are this ground was in the original specs of the job, that included the installation of said panel.
 
The raceway is required to be continuous.

300.10 Electrical Continuity of Metal Raceways and Enclosures.

Metal raceways, cable armor, and other metal enclosures for conductors shall be metallically joined together into a continuous electrical conductor and shall be connected to all boxes, fittings, and cabinets so as to provide effective electrical continuity. Unless specifically permitted elsewhere in this Code, raceways and cable assemblies shall be mechanically secured to boxes, fittings, cabinets, and other enclosures.
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As for an interruption of continuity, people can forget to tighten a set screw as easily as they can fail to properly tighten a connection on the grounding conductor.

Metal raceways are permitted to be used as equipment grounding conductors, people choose to run additional grounding conductor solely by choice with exception of health care facilities and a few other locations.

With the transformer idea installing a grounding electrode conductor for the separately derived system may make this just as impractical as pulling a separate grounded circuit conductor with the original feeder. 200 feet of #4 will cost less than transformer, supply breaker, load center - with main if 3 wire secondary, grounding electrode installation - possibly lengthy , and the labor to do all of that. On the other hand using the raceway as the equipment ground and making the #4 into a neutral can be done in an hour or less and there is nothing wrong with it.

I haven't double checked the derating allowed on the neutral, but other than this (or even this) can anyone find faults in this solution?
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The neutral only need to be sized for the load that it will carry. With a minimum size according to 250.66 I believe although I am having trouble finding where it says this.
 
kwired said:
....The neutral only need to be sized for the load that it will carry. With a minimum size according to 250.66 I believe although I am having trouble finding where it says this.
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Probably thinking of 215.2(A)(1) referencing 250.122. Always hard for me to find too for some reason :).

I assume a #6 min unless OCP is less than 150 amps 250.122(B).
 
Volta said:
Probably thinking of 215.2(A)(1) referencing 250.122. Always hard for me to find too for some reason :).

I assume a #6 min unless OCP is less than 150 amps 250.122(B).
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Thank you,

I don't know how many times I skipped right over 215.2 when I was trying to find this - I knew it was there somewhere. I had 250.66 in my mind but I see it is 250.122 which makes sense it only needs to be able to carry the current required to operate the overcurrent device or the actual load which ever requires the larger conductor.
 
... or otherwise run with the circuit conductors ... could mean in the same trench, wireway, buss duct, open conductors, or cable tray. Am I missing anything else the section mentioned cable or raceway.

250.102(E) permits an equipment bonding jumper to be installed on the outside of a raceway or enclosure but limits it to 6 feet in length and it must be routed with the raceway or enclosure.
 
If your going to do the job why cut corners ? The customer needs a dedicated circuit, it doesn't sound like it's a poor widow that can't afford the work. WHY,WHY,WHY cut corners? I personally don't like EMT as the ground path. Yes it is code compliant, if it is a low resistance path etc etc, but I have come across too many separated ( old ) EMT runs, that were supposed to be the ground path. Go ahead and do a CODE MINIMUM job, it will pass the inspection. Sucks to be your customer.
 
Just re-read the original post and it sounds like the job was already done using the egc as the neutral and the emt as the egc.
 
acrwc10 said:
If your going to do the job why cut corners ? The customer needs a dedicated circuit, it doesn't sound like it's a poor widow that can't afford the work. WHY,WHY,WHY cut corners? I personally don't like EMT as the ground path. Yes it is code compliant, if it is a low resistance path etc etc, but I have come across too many separated ( old ) EMT runs, that were supposed to be the ground path. Go ahead and do a CODE MINIMUM job, it will pass the inspection. Sucks to be your customer.
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You really think so after he saved them thousands of dollars?
 
infinity said:
You really think so after he saved them thousands of dollars?
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YA, I do. If a tire shop puts a cheap patch on a tire instead of replacing it, you save money now, but if it blows out on the freeway and you total the car how is that savings ? Cheap is cheap, it is not savings.
"Penny wise and pound foolish".
This is a store, what type of equipment is now at risk, due to a questionable ground? Seeing that the solution in the OP is written in the past tense, it is a mute point. The job is done, to a code minimum. So I guess it must be safe.:roll:
 
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