Remote distribution panel or subpanel?

[Jeffrey R. Pope]

Originally Posted by pabernathy

Author’s Comment: When an equipment grounding conductor is not run to a separate building or structure, the grounded (neutral) conductor must be used to provide the effective fault current path required to clear any line-to-case faults in addition to carrying any unbalanced neutral current.

. . .and it must be connected to the building or structure disconnecting means (in other words, a switched or fused neutral, no?)

I'm about to start my final inspection for the day. I'll check back in later. . .

[tdietrich1]

Originally Posted by pabernathy

P.s...those are Mr. holts comments...not mine...

Thought they were familiar.

As for Marc, I think the dude is on the Marc! (pun intended).

tom

[Paul W. Abernathy]

250.6 Objectionable Current over Grounding Conductors.

(A) Arrangement to Prevent Objectionable Current.

The grounding of electrical systems, circuit conductors,
surge arresters, and conductive non

–current-carrying materials
and equipment shall be installed and arranged in a
manner that will prevent objectionable current over the
grounding conductors or grounding paths.

This would make it a compelling argument to NOT tie the Grounded and Grounding conductors together in a 4 wire setup to a detached garage so to speak....the 250.32(B)(2) section has been debated for many years.....some think it will disappear in future cycles....

[Marc D. Shunk]

I wouldn't connect the feeder ECG to the bar either, and havn't said that's proper. It's okay that they ran 4-wire and only have the panel connected as 3-wire, but the ECG should remain unconnected. It is a parallel path for the neutral. The panel has plenty of issues, but being connected as a 3-wire panel is not among them.

[Greg Fretwell]

Jeff that is telling you to bond the 3 wire feeder grounded conductor to the disconnect enclosure, where you also connect the ground electrode conductor. This is simply treating the second building like the first where you had a 3 wire service drop.
If there is a 4th wire in the feeder you WILL NOT reground the neutral in the second building. I doubt an inspector would simply let you tiee it back if he saw it was avaiable. It is true 250.32(B)(2) is going to be deleted in the 2008 assuming there is no last minute stay of execution. This is the same logic that made 250.50 go away (3 wire to dryers/ranges). The war is over, there is no reason to save copper anymore. Cost is no object if you can squeeze out another .0001% of safety ... or so it seems.

[Jeffrey R. Pope]

I understand the practical application of a 3-wire feed, and I know that installers/technicians say that it's proper, but you will have a difficult time convincing me that the code implies anything other than what it says.

Where an equipment grounding conductor is not run with the supply to the building or structure, the grounded circuit conductor shall be connected to the building or structure disconnecting means

This is simply one of the reasons why I say "a home inspector should defer a 3-wire feed to a qualified electrician."

I am not going to try and convince anyone that my interpretation is absolute, and I'm not going to try and verify "no other metallic pathway." I'm going to state that the three wire feed should be verified as compliant by a qualified electrician (or something to that affect).

[Greg Fretwell]

You still have 225.38 that says this can be (dis)connected via a busbar.

This is the example in the handbook, see a disconnect on the neutral?

[brian winkle]

250.32 (B)(2) Grounded Conductor. Where (1) an equipment grounding conductor is not run with the supply to the building or structure, (2) there are no continuous metallic paths bonded to the grounding system in both buildings or structures involved, and (3) ground-fault protection of equipment has not been installed on the common ac service, the grounded circuit conductor run with the supply to the building or structure shall be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded.




The intent is to connect the grounded conductor to the disconnect for grounding and bonding of the equipment, just like it is required at other equipment. The last part of the section makes this clear.

[Paul W. Abernathy]

Brian,

Yep...as long as all the FACTORS in that article are met. Just want guys to be clear that IF you have a 4 wire setup to a detached garage....you MUST have the Grounded and Grounding separated as you would normally see in a typical "remote" distirbution setup in a dwelling......lets not confuse the two as 250.32(B)(2) is very specifiic in nature.

[Jeffrey R. Pope]

It will certainly be easier when/if this section of the code "goes away." I like the thought that the 4-wire feed will be the new mandate, but until then, I still see this as a switched or fused neutral.

Where an equipment grounding conductor is not run with the supply to the building or structure, the grounded circuit conductor shall be connected to the building or structure disconnecting means.

Disconnecting Means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.

I'm not arguing with any of you that there cannot be a different intent than what I am proposing, I'm simply giving you the information as I understand it and as it was explained to me by two different city inspectors.

[Paul W. Abernathy]

Jeff,

I agree 100% with the premise.....I would prefer to see them as a 4 wire setup all the time.....IN fact MANY agree with that as well as their are simply too many " What If's " involved with 250.32(B)(2) but alas the NEC panel does not agree......so it will still be done and technically safe if done correctly.

I am confused however in your use of the term Switched or Fused Neutral in either setup. The neutral ( grounded ) conductor is solidly connected in either system setup......the only time we get into switching a neutral would be in a SDS setup....in which it defines THAT type of setup....so I am confused ( not argueing my friend....I think you know me now )...just trying to learn myself why you would consider it such.

[Greg Fretwell]

Someone better explain your view to NFPA. They get it "wrong" (by your interpretation) in the handbook. Basically you are saying it is illegal to use a panelboard main breaker as the disconnect in a second building since that will not interrupt the neutral.

[Jeffrey R. Pope]

I read "disconnecting means" as a switch or OCPD, not a lug or bus terminal that is screwed down.

The section clearly (ok, maybe not so clearly ) states that the grounded conductor shall be connected to the "disconnecting means."

[Paul W. Abernathy]

As greg stated......it is simply not a case where you want to even think about the "grounded" conductor being switched or fused...simply not the case when it comes to a detached building as in this question.

[Greg Fretwell]

BTW if the hot rumor is true you will not get any help from 2008 code in Florida. There is a buzz that the 2008 will be skipped and they are going to stay with 2005 until the 11 code comes out. They plan to pick up anything they like with the "glitch" amendments to the FBC (as they did with the required bonding of steel framing)