Just curious on some opinions, in the 2008NEC xfmr. secondary conductors are indicated to feed a single load. Does this mean that when supplying a panelbaord for the secondary of a transformer (max. 10?) that a double lug / sub-feed on the panelboard or even a thru-feed is no longer code compliant when installed from a transformer secondary conductor?
xfmr secondaries 2008nec
- Thread starter Mike01
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Mike,
What code section are you looking at? I don't see much for changes in 240.21(C).
Don
What code section are you looking at? I don't see much for changes in 240.21(C).
Don
additional line:
additional line:
The change was made to the first line of 240.21( C):
It states ?A set of conductors feeding a single load, or each? this was the change to indicate that multiple feeders can be connected to the secondary of a transformer to feed multiple loads, My question is does this mean you can no longer land the secondary conductors in a double lugged MCB panel board? You would then have two loads and not a ?single load? correct?
additional line:
The change was made to the first line of 240.21( C):
It states ?A set of conductors feeding a single load, or each? this was the change to indicate that multiple feeders can be connected to the secondary of a transformer to feed multiple loads, My question is does this mean you can no longer land the secondary conductors in a double lugged MCB panel board? You would then have two loads and not a ?single load? correct?
Mike01,
2005 code says, "Eachset of conductors feeding seperate loads----" 2008
code added, " A set of conductors feeding a single load ----"
So either a single load or seperate loads may use this section.
To answer your question: nothing has changed, only added to.
2005 code says, "Eachset of conductors feeding seperate loads----" 2008
code added, " A set of conductors feeding a single load ----"
So either a single load or seperate loads may use this section.
To answer your question: nothing has changed, only added to.
- Location
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- retired electrician
underlined is new text italics is text to be deleted
10-26 Log #2939 NEC-P10 Final Action: Accept in Principle
(240.21(C))
______________________________________________________________
Submitter: Philip Simmons, Simmons Electrical Services
Recommendation: Revise the existing section as follows:
(C) Transformer Secondary Conductors. One or more Each set (s) of
conductors feeding separate loads shall be permitted to be connected to a
transformer secondary, without overcurrent protection at the secondary, as
specified in 240.21(C)(1) through (6). The provisions of 240.4(B) shall not be
permitted for transformer secondary conductors.
Retain the existing FPN.
Substantiation: The efforts made by CMP-10 to clarify this section for the
2005 NEC are appreciated. However, it appears the first sentence can be
improved upon for clarity. When read literally, sets of conductors are required
to feed separate loads, not the same load. We know that more than one set
of conductors often supply the same load when installed as parallel sets of
conductors.
It seems the changes made by CMP-10 were intended to clarify that more
than one set of conductors are permitted to be connected to a transformer
secondary so long as the provisions of (C)(1) through (C)(6) are complied with.
Hopefully, the above changes will maintain the concept of multiple connections
being permitted while not requiring the sets of conductors to supply different
loads.
Panel Meeting Action: Accept in Principle
Revise the text in the proposal as follows:
“(C) Transformer Secondary Conductors. A set of conductors feeding a single
load, or each set of conductors feeding separate loads, shall be permitted...”.
Panel Statement: The panel has added wording to clarify that more than one
set of conductors often supply the same load when installed as parallel sets of
conductors. The panel does not agree with removal of the reference to separate
loads. The intent of the 2005 Code change was to clarify that these secondary
conductor rules are not limited in their application to one set per transformer.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
10-26 Log #2939 NEC-P10 Final Action: Accept in Principle
(240.21(C))
______________________________________________________________
Submitter: Philip Simmons, Simmons Electrical Services
Recommendation: Revise the existing section as follows:
(C) Transformer Secondary Conductors. One or more Each set (s) of
conductors feeding separate loads shall be permitted to be connected to a
transformer secondary, without overcurrent protection at the secondary, as
specified in 240.21(C)(1) through (6). The provisions of 240.4(B) shall not be
permitted for transformer secondary conductors.
Retain the existing FPN.
Substantiation: The efforts made by CMP-10 to clarify this section for the
2005 NEC are appreciated. However, it appears the first sentence can be
improved upon for clarity. When read literally, sets of conductors are required
to feed separate loads, not the same load. We know that more than one set
of conductors often supply the same load when installed as parallel sets of
conductors.
It seems the changes made by CMP-10 were intended to clarify that more
than one set of conductors are permitted to be connected to a transformer
secondary so long as the provisions of (C)(1) through (C)(6) are complied with.
Hopefully, the above changes will maintain the concept of multiple connections
being permitted while not requiring the sets of conductors to supply different
loads.
Panel Meeting Action: Accept in Principle
Revise the text in the proposal as follows:
“(C) Transformer Secondary Conductors. A set of conductors feeding a single
load, or each set of conductors feeding separate loads, shall be permitted...”.
Panel Statement: The panel has added wording to clarify that more than one
set of conductors often supply the same load when installed as parallel sets of
conductors. The panel does not agree with removal of the reference to separate
loads. The intent of the 2005 Code change was to clarify that these secondary
conductor rules are not limited in their application to one set per transformer.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
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