Sub Panel question on conduit

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  #41  
Old 08-27-15, 12:36 PM
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So now that you mentioned the need of a appropriately sized jumper, may you explain further about that term to me? What would be a good sized jumper between the Neutral and Ground in the case the GEC terminates in the Ground bus bar???
I would use a jumper of the same size as the GEC which in most cases would be a #6 copper.

Here is a reference I like by a reknowned code expert, Charlie Trou, taken from Electrical Contractor magazine, May 2013.

Q: Does the grounding electrode conductor have to be connected to the neutral bus, or can it be connected to the ground bus?



A: NEC 250.24(4) permits the grounding electrode conductor to be connected to the ground bus in the panelboard if there is a wire from the ground bus to the neutral bus. Using the panelboard housing as a conductor is not permitted.

Connecting The Grounding Electrode Conductor, Protecting Copper And More | EC Mag




I thought that only one ground connection was correct as the neutral is bonded to the ground in the service entrance or main panel? But what do I know.
You need two ground connections. In most residential cases it is the ground rod and the water service. Yes, the neutral is grounded in the main panel where the main disconnect is located which usually is a main circuit breaker.
 
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  #42  
Old 08-27-15, 12:41 PM
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Found the answer to my original question

Here is a link to what I was really asking in the first post here...Now I can relax.

Understanding the need for a floating neutral in a sub-panel. - InterNACHI Inspection Forum
 
  #43  
Old 08-27-15, 12:46 PM
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You need two ground connections. In most residential cases it is the ground rod and the water service. Yes, the neutral is grounded in the main panel where the main disconnect is located which usually is a main circuit breaker.
Well in Florida we have plastic underground water pipes so that leaves no 2nd option. What to do then? In my case it is a 2400 square foot steel building and although there is not an Ufer ground, maybe ground to the steel frame of the building? Probably should have thought of the Ufer ground when I had the slab poured.
 
  #44  
Old 08-27-15, 12:56 PM
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Note: I removed my comment I just want Grumple to read it at least once.

And he did it...


Thank you.


Jos B-)
 
  #45  
Old 08-27-15, 01:04 PM
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Notice: I removed my comment too and will not attempt to communicate with Jos ever again!
 
  #46  
Old 08-27-15, 01:05 PM
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Gentlemen.... this bickering needs to end and end now !
Please post "on topic" and leave the remarks out.
 
  #47  
Old 08-27-15, 01:08 PM
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I thought I was being nice. Oh well...I will not reply to Jos anymore. I promise.
 
  #48  
Old 08-27-15, 01:11 PM
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Thumbs up

CasualJoe,

Thanks for the information regarding the use of a appropriately sized jumper from the Neutral to Ground bus bars.


I appreciated it.



Jos
 
  #49  
Old 08-27-15, 01:14 PM
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At least one additional ground rod will satisfy the code requirement since you have plastic water service. The steel structure should be bonded to the grounding electrode system (via #8 copper IIRC), but does not count as a grounding method unless you essentially have an Ufer ground in the footings with a stainless or copper rebar coming up to bond to.
 
  #50  
Old 08-27-15, 05:33 PM
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ibpooks,
Thanks for the reply. I already have 2 ground rods at the workshop. Just to be clear, are 2 ground rods connected to one conductor ok or is it 2 separate ground rods with 2 separate conductors connected at the service panel? Normally to reach the 25 ohm ground requirement it is best done with 2 ground rods and a single #4 or #6 bare copper wire and I have 2 connected with one conductor.
G
 
  #51  
Old 08-27-15, 05:37 PM
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Two ground rods on a single piece of #6 wire is fine. The single wire should not be cut at the second ground rod.

I usually strip about two inches of insulation from the area where the ground rod is, fold in half and place behind the ground football clamp.
 
  #52  
Old 08-27-15, 05:54 PM
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Two ground rods on a single piece of #6 wire is fine. The single wire should not be cut at the second ground rod.

I usually strip about two inches of insulation from the area where the ground rod is, fold in half and place behind the ground football clamp.
I used 2 acorn clamps on each rod and spaced them 16 feet apart as an 8 foot rod should be a minimum of 8 feet apart to the second rod and more is better for the sphere of influence. I think I am good there.
Thanks,
G
 
  #53  
Old 08-27-15, 06:10 PM
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The conductor only need to be continuous to the first rod. After that it is a bonding jumper.
 
  #54  
Old 08-27-15, 06:29 PM
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The conductor only need to be continuous to the first rod. After that it is a bonding jumper.
Good to know. Thanks. Mine are both continuous (house and shop) but my next question for future reference was going to be:

Exothermic welds. Are they considered equal to a single conductor?

The reason I ask is if I decided to add a 3rd ground rod to my dual ground rod setup so it is equal to my house arrangement, would I have to run a new bare #4 or #6 to connect to all 3. But I think you answered that. Cool. Never used exothermic welds as $15 vs $2 for a clamp...
Thanks,
G
 
  #55  
Old 08-27-15, 06:45 PM
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Exothermic welds and irreversible crimps are considered a continuous conductor.
 
  #56  
Old 08-27-15, 08:55 PM
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Exothermic welds and irreversible crimps are considered a continuous conductor.
pcboss,
Thank you. I am gonna sleep good tonight.
G
 
  #57  
Old 08-28-15, 03:13 PM
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Two ground rods on a single piece of #6 wire is fine. The single wire should not be cut at the second ground rod.

I usually strip about two inches of insulation from the area where the ground rod is, fold in half and place behind the ground football clamp.
PJmax,
I read this a few times and just to be clear, what do you mean "the wire should not be cut at the second ground rod"? I use bare copper so I have no insulation. Just curious about the "not be cut" part.
Thanks,
G
 
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