New Sub Panel

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LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Here on a service up-grade you would have to show that it is really going to be cost prohibitive to change out the feeder.
I had to do that on a residential genny install, where it would have been impossible to resupply the major appliances with 4-wire feeds, without exiting the slab-on-grade garage, cutting sidewalks and patios, and entering the slab-on-grade house, where the kitchen was not on any exterior wall.

The best people to consult are the local authorities.
Absolutely. I've found that inspectors appreciate being consulted, and they're the ones who will be judging the install anyway.
 

glene77is

Senior Member
Location
Memphis, TN
IMO here in MA our 'Rule 3' would mean it is not my problem and if it is a 'real hazard' Rule 4 applies making it the inspectors problem.

iWire,
This "Set" of rules sounds interesting, at least for a thoughtful moment.
So, What are the Rules #1 and #2 ? :-?
 

iwire

Moderator
Staff member
Location
Massachusetts
iWire,
This "Set" of rules sounds interesting, at least for a thoughtful moment.
So, What are the Rules #1 and #2 ? :-?

Will I see you working up here? :D


Insert the following provisions ahead of the body of the Code:

Rule 1. All installations, repairs and maintenance of electrical wiring and electrical fixtures used for
light, heat, power, signaling and communications purposes in buildings and structures
subject to the provisions of M.G.L. c. 143 shall be reasonably safe to persons and property.

Rule 2.
Conformity of installations, repairs, and maintenance of electrical wiring and electrical
fixtures used for light, heat, power, signaling and communications with applicable
regulations set forth in the Code, which is hereby filed with the Secretary of the
Commonwealth shall be considered as complying with these requirements.

Rule 3. Additions or modifications to an existing installation shall be made in accordance with this
Code without bringing the remaining part of the installation into compliance with the
requirements of this Code. The installation shall not create a violation of this Code, nor shall
it increase the magnitude of an existing violation.

Rule 4. Where an actual hazard exists, the owner of the property shall be notified in writing by the
authority enforcing this Code. The notification shall contain specifications of the actual
hazard that exists, together with a reference to the rule of this Code that is now in violation.

Rule 5. References are made in this code to other standards. Those standards, where duly adopted by
law or regulation, may be enforced by the appropriate official. They are not considered part
of this Code and they are not enforceable under M.G.L. c. 143 ? 3L. For Massachusetts
Building Code references, see Appendix A.

Rule 6. The approving authority may be guided in his approval of specific items of equipment and
materials contemplated by the Code, by proof that such equipment and materials have been
tested and conform to suitable recognized industry standards.

Rule 7. 527 CMR 12.00 shall be effective on all installations for which a permit has been granted
subsequent to December 31, 2010. For installations governed by permits issued after
November 1, 2010 and before January 1, 2011, the applicable code shall be the version of
527 CMR 12.00 in effect on November 1, 2010.

Rule 8. In accordance with the provisions of M.G.L. c. 143 ? 3L, the permit application form to
provide notice of installation of wiring shall be uniform throughout the Commonwealth, and
applications shall be filed on the prescribed form. After a permit application has been
accepted by an Inspector of Wires appointed pursuant to M.G.L c. 166 ?32, an electrical
permit shall be issued to the person, firm or corporation stated on the permit application.
Such entity shall be responsible for the notification of completion of the work as required in
MGL 143 ?3L.
Permits shall be limited as to the time of ongoing construction activity, and may be
deemed by the Inspector of Wires abandoned and invalid if he or she has determined that the
authorized work has not commenced or has not progressed during the preceding 12-month
period. Upon written application, an extension of time for completion of work shall be
permitted for reasonable cause. A permit shall be terminated upon the written request of
either the owner or the installing entity stated on the permit application.

Rule 9. Installations covered by 527 CMR 12.00 shall also comply with M.G.L. c. 141.

Rule 10. Electrical installations shall not be concealed or covered from view until inspected by the
inspector of wires within and not more than 24 hours for exterior excavations nor more than
72 hours for interior installations after proper notice to the inspector, Saturdays, Sundays,
and holidays excluded.
 

laketime

Senior Member
I talked to the inspector and the feeder is run in EMT. He is only requiring a ground busing on each end of the existing EMT.
 

Benton

Senior Member
Location
Louisiana
I feel it may be our responsibility to bring it to the the attention of the customer and after that is up to them to decide to spend the money or not.





Exactly how it had been.

I agree with this completely. I have encountered this a few times where your intentions may be good, but their wallets aren't.
 

tryinghard

Senior Member
Location
California
There are different perspectives here 1) regulations specifying what is acceptable to do or leave as pre-existing and 2) code specifying what is allowed. Either perspective should be predicated on the intent of correct sub panel bonding.

I am arguing correcting ?a wrong? to eliminate the hazard based on what code allows in light of the reason for this code, and I am suggesting this is best asserted rather than persuading the customer by trying to educate them. You may choose to follow regulations allowing existing hazards to remain and so-be-it but the fact remains in this case the sub panel bonding is in violation of NEC and the possibility of paralleling current on non-conductors and where it does not belong is most certain along with all the other nuisances caused by this incorrect bonding.

This can be likened to a dentist that determines the need to replace a failed crown, the dentist could take off the old notice some abscess and put the new crown on anyway or clean the abscess when revealed ? it?s that simple. You just make the choice.

Related codes: 250.142(B), 250.24(A)(5), 250.6 (Objectionable Current)
 

tryinghard

Senior Member
Location
California
250.6 has to do with disconnecting grounding connections.

This would be true if you minimize 250.6 down to (B) only but there are 4 other subsections, (A) ?Arrangement to prevent objectionable current?shall be installed and arranged in a manner that will prevent objectionable current.?


OK 250.6 has nothing to do with requiring an EGC with a feeder.

The feeder is the supply to the subpanel if this supply is incorrect it is impossible to correctly bond the subpanel by the fact that there will not be enough conductors. This makes the feeder integral with 250.6 because it being misapplied causes violation of this code and the others.
 

tryinghard

Senior Member
Location
California
…will you install a feeder this way?
No, but that has nothing to do with 250.6

I wouldn’t either and I can’t answer for your reason but my reason is to prevent objectionable current (parallel neutral paths). If the emphasis is to find a way to correct it, it often does reveal as this post did, the EMT type EGC can be used allowing separation of the neutral bonding. But if the emphasis is to find a way to leave it this can be found as well meaning the objectionable current and hazards will remain.

Using Mike Holts letter through EC&M helps "Objectionable current on grounding and bonding paths occur when an improper neutral-to-case bond creates a parallel path for neutral current to return to the power supply via metal parts of the electrical system in violation of 250.142"
 
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iwire

Moderator
Staff member
Location
Massachusetts
I wouldn?t either and I can?t answer for your reason but my reason is to prevent objectionable current (parallel neutral paths). If the emphasis is to find a way to correct it, it often does reveal as this post did, the EMT type EGC can be used allowing separation of the neutral bonding. But if the emphasis is to find a way to leave it this can be found as well meaning the objectionable current and hazards will remain.

Using Mike Holts letter through EC&M helps "Objectionable current on grounding and bonding paths occur when an improper neutral-to-case bond creates a parallel path for neutral current to return to the power supply via metal parts of the electrical system in violation of 250.142"

I must be missing something as I see no objectionable currents or parallel paths in the OPs situation.

All I see is a panel that at first he said had no EGC.

I am installing a new sub panel to replace an existing Federal panel. I do not believe the feed has a ground wire installed.

It turned out he had an EGC as the circuit was run in EMT.
 

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
I wouldn?t either and I can?t answer for your reason but my reason is to prevent objectionable current (parallel neutral paths). If the emphasis is to find a way to correct it, it often does reveal as this post did, the EMT type EGC can be used allowing separation of the neutral bonding. But if the emphasis is to find a way to leave it this can be found as well meaning the objectionable current and hazards will remain.

Using Mike Holts letter through EC&M helps "Objectionable current on grounding and bonding paths occur when an improper neutral-to-case bond creates a parallel path for neutral current to return to the power supply via metal parts of the electrical system in violation of 250.142"

I must be missing something as I see no objectionable currents or parallel paths in the OPs situation.

All I see is a panel that at first he said had no EGC.



It turned out he had an EGC as the circuit was run in EMT.

This could happen 'if' the EGCs of the two panels were connected together in an outlet.
 

iwire

Moderator
Staff member
Location
Massachusetts
This could happen 'if' the EGCs of the two panels were connected together in an outlet.


No

1) The OP had stead there was no EGC, no EGC no chance for it to be connected.

2) EGCs are almost always in parallel with each other and that is not a problem or objectionable current IMO.
 

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
No

1) The OP had stead there was no EGC, no EGC no chance for it to be connected.

2) EGCs are almost always in parallel with each other and that is not a problem or objectionable current IMO.

Bob

Maybe I was not clear. If EGCs from different panels are connected there is a paralled path for the grounded conductor 'if' panel #2 does not seperate the grounded conductor and the EGC.
 

tryinghard

Senior Member
Location
California
Without an EGC run to the sub panel the neutral is most likely bonded (or the enclosure is not effectivley grounded) also all neutrals and equipment grounds would be common, this violates 250.142(B) and creates parallel paths - objectionable current violating 250.6.
 

tryinghard

Senior Member
Location
California
I must be missing something as I see no objectionable currents or parallel paths in the OPs situation.

All I see is a panel that at first he said had no EGC.



It turned out he had an EGC as the circuit was run in EMT.

The intent/purposes of 250.142(B) & 250.24(A)(5) are to eliminate objectionable current (parallel neutral paths), this is why each are integral with 250.6 and why feeders must include EGC?s. Any time neutrals common with EGC?s in multiple locations parallel paths will occur if anyway at all through earth but most likely multiple paths like water pipes and such as well as negative power quality and electronic issues. The unbalanced load will follow all paths according to each level of resistance to the source, the best we can do is contain this entire load on the grounded conductor.
 

iwire

Moderator
Staff member
Location
Massachusetts
The intent/purposes of 250.142(B) & 250.24(A)(5) are to eliminate objectionable current (parallel neutral paths), this is why each are integral with 250.6 and why feeders must include EGC?s. Any time neutrals common with EGC?s in multiple locations parallel paths will occur if anyway at all through earth but most likely multiple paths like water pipes and such as well as negative power quality and electronic issues. The unbalanced load will follow all paths according to each level of resistance to the source, the best we can do is contain this entire load on the grounded conductor.

You seem to be stuck, the OPs situation had no parallel paths, no multiple connections from neutral to earth therefore no 'objectionable current' for 250.6 to address.
 
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