9-144 Log #3446 NEC-P09 Final Action: Accept
(450.10(A) (New) )
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TCC Action: The Correlating Committee understands that the Exception
is also new text.
Submitter: Michael J. Johnston, National Electrical Contractors Association
Recommendation: Add new text to read as follows:
(A) Dry-Type Transformer Enclosures. Where separate equipment grounding
conductors and supply-side bonding jumpers are installed, a terminal bar for all
grounding and bonding conductor connections shall be secured inside the
transformer enclosure. The terminal bar shall be bonded to the enclosure in
accordance with 250.12 and shall not be installed on or over any vented portion
of the enclosure.
Exception. Where a dry-type transformers is equipped with wire-type
connections (leads), the grounding and bonding connections shall be permitted
to be connected together using any of the methods in 250.8 and shall be bonded
to the enclosure, if of metal.
Include the current text of this section as Subdivision (B) and new title as
follows:
(B) Other Metal Parts. Insert current text of this section unchanged.
Substantiation: The connections of grounding and bonding conductors in drytype
transformer enclosures continue to be problematic and inconsistently made
without clear requirements in the NEC. It is very common to see grounding
and bonding conductors connected to the enclosure at or over the venting
openings in the bottom of the transformer, resulting in less than effective
connections. I don?t believe these enclosures have been evaluated as grounding
and bonding equipment and should not be depended upon to serve as effective
ground fault current paths. The requirement for a terminal bar eliminates the
inconsistencies and provides needed direction for installers.
Panel Meeting Action: Accept
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12