grounding / choke

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rayertz

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see attached picture.

I have a 2/0 ground conductor grounding an electro deposition tank in six locations. We have a # 6 tapping off the 2/0 going back to the RGC bond bushing (choke). The Safety department is saying the application is not right. They are saying the 2/0 should go thru the bond bushing.
I am thinking since the 2/0 cable is insulated the # 6 is not even required.

Please advise, thank you...
 

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jumper

jumper

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I am pretty sure that the bonding jumper should be full sized or run the GEC through that bushing.

That #6 is undersized.

I do not believe that the fact that the GEC is insulated mitigates the size of the jumper.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Jumper's reply is correct.

Also the fact the conductor has insulation has nothing to do with why we must bond this.

What you have with a single conductor in a ferrous enclosure is essentially a one turn core and coil, the impedance of that conductor will rise when there is current in the conductor. If anything the fact the GEC is insulated the need for the bond is even greater then if it were a bare conductor - but only slightly greater as a bare conductor still needs a solid bond instead of a loose bond.
 
roger

roger

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rayertz said:
see attached picture.

I have a 2/0 ground conductor grounding an electro deposition tank in six locations. We have a # 6 tapping off the 2/0 going back to the RGC bond bushing (choke). The Safety department is saying the application is not right. They are saying the 2/0 should go thru the bond bushing.
I am thinking since the 2/0 cable is insulated the # 6 is not even required.

Please advise, thank you...
Click to expand...

What you seem to be describing is an "Auxiliary Grounding Electrode" (before 2008 it was called "Supplemental Grounding Electrode" as shown it the illustration) and there is really no rules for them like there is for the GES and GEC, they are permitted but not required as far as the NEC is concerned so it could be left as is with no problem.

1004224701_2.gif


Roger
 
jumper

jumper

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3 Hr 2 Min from Winged Horses
roger said:
What you seem to be describing is an "Auxiliary Grounding Electrode" (before 2008 it was called "Supplemental Grounding Electrode" as shown it the illustration) and there is really no rules for them like there is for the GES and GEC, they are permitted but not required as far as the NEC is concerned so it could be left as is with no problem.

Roger
Click to expand...

Assuming that it is an Auxiliary Grounding Electrode installed according to 250.54, I do not see where that section relieves you from 250.64(E)(1) requirements. Am I missing something?
 
roger

roger

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jumper said:
Assuming that it is an Auxiliary Grounding Electrode installed according to 250.54, I do not see where that section relieves you from 250.64(E)(1) requirements. Am I missing something?
Click to expand...

Derek, I can kind of see it that way too but, in the case of these tanks do they fit any of the descriptions included in 250.64. I know they are structures but are there any feeders or branch circuits connected to them?

250.64 Grounding Electrode Conductor Installation.
Grounding electrode conductors at the service, at each
building or structure where supplied by a feeder(s) or
branch circuit(s), or at a separately derived system shall be
installed as specified in 250.64(A) through (F).
Click to expand...


Roger



 
jumper

jumper

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roger said:
Derek, I can kind of see it that way too but, in the case of these tanks do they fit any of the descriptions included in 250.64. I know they are structures but are there any feeders or branch circuits connected to them?

Roger
Click to expand...

OP said "electro deposition tank " so I was guessing there is a circuit or feeder.:?
 
J

jap

Senior Member
Occupation
Electrician
jumper said:
I am pretty sure that the bonding jumper should be full sized or run the GEC through that bushing.

That #6 is undersized.

I do not believe that the fact that the GEC is insulated mitigates the size of the jumper.
Click to expand...


That would be ideal, but, seeing as how the factory lug that comes with the bonding bushing is never near large enough for the full size conductor that is pulled through it, it would tend to make one wonder if the bonding jumper actually had to be that large at all.

Unless you change the lug out on the bonding jumper to accommodate the full size conductor and somehow create a pig tail out of the larger conductor to be able to turn it into it.

JAP>
 
ADub

ADub

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You could change your rigid to aluminum rigid and forget bonding it all together


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don_resqcapt19

don_resqcapt19

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x_hw175-17-4_72dpi.jpg

You can use a conduit fitting like this. No jumper required. The fitting provides the required full size bonding between the grounding conductor and the conduit.
 
ADub

ADub

Senior Member
Location
Midwest
Occupation
Estimator/Project Manager
don_resqcapt19 said:
x_hw175-17-4_72dpi.jpg

You can use a conduit fitting like this. No jumper required. The fitting provides the required full size bonding between the grounding conductor and the conduit.
Click to expand...

Good lord I love it! Got a model number?


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kwired

kwired

Electron manager
Location
NE Nebraska
K8MHZ said:
Why would that be true? Aluminum is metallic, conducts electricity even better than ferrous conduit or tubing and acts like a choke just like ferrous conduit or tubing.
Click to expand...

I agree it is a better conductor then ferrous materials would be. I (think) it has significantly less magnetic properties then ferrous materials though and would not have anywhere the same choke effect. It likely still needs bonded in at least one location though.
 
ADub

ADub

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Midwest
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Estimator/Project Manager
K8MHZ said:
Why would that be true? Aluminum is metallic, conducts electricity even better than ferrous conduit or tubing and acts like a choke just like ferrous conduit or tubing.
Click to expand...

Try 250.64(e)(1). Aluminum is non ferrous and not required to be bonded at both ends as per the article.


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GoldDigger

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Before applying Lenz's Law to this situation you need to consider the geometry involved.
For a straight wire, Lenz predicts two things:
1. Circulating currents caused by the changing magnetic field which in turn create an electric field that opposed the original current. This is the mechanism behind the skin effect. This is a second order effect.
2. The magnetic field around the wire forming a fractional turn air core inductor which opposes any changes in current. This is a first order effect which is small for an air core of the size involved.
Add an aluminum raceway and you have an aluminum core inductor. Not much change.
Add a ferrous raceway and you have an iron core inductor. Big effect!.
Conclusion: their is an increase in impedance with aluminum, but nowhere near what you get with steel (except for non-magnetic alloys)
 
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