Spare Conductors

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quantum

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Is there anything allowing or prohibiting the installation of spare/unnecessary conductors in a raceway in the NEC? I thought I read something before, but I'm not able to locate it. On an aside, I'm trying to convince a design engineer that we do not need an EGC running on the supply side of a service drop.
 
No, as long as the spare conductors are counted when determining the ampacity adjustment factor. In fact, the description of Table 310.15(B)(3)(a) specifically mentions spare conductors.
 
quantum said:
Is there anything allowing or prohibiting the installation of spare/unnecessary conductors in a raceway in the NEC? I thought I read something before, but I'm not able to locate it. On an aside, I'm trying to convince a design engineer that we do not need an EGC running on the supply side of a service drop.
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As for the second part of your question, installing an EGC on the supply side of a service disconnect would be a violation as it will be in parallel with the grounded conductor due to required bonding of the neutral at the POCO transforner by the NESC and bonding at the service disconnect required by the NEC.
 
EC Dan said:
No, as long as the spare conductors are counted when determining the ampacity adjustment factor. In fact, the description of Table 310.15(B)(3)(a) specifically mentions spare conductors.
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It seems strange that it would say "the total number of conductors in the raceway, including spare conductors" while neutrals (normally) and grounds in the raceway do not count. It also says that conductors that cannot be energized simultaneously do not add; why would conductors that cannot be energized at all count towards the total? Maybe because they could be energized in the future, I guess.
 
ggunn said:
It seems strange that it would say "the total number of conductors in the raceway, including spare conductors" while neutrals (normally) and grounds in the raceway do not count. It also says that conductors that cannot be energized simultaneously do not add; why would conductors that cannot be energized at all count towards the total? Maybe because they could be energized in the future, I guess.
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The table description goes on to say the count is adjusted in accordance with 310.15(B)(5) and 310.15(B)(6), which clarifies when to count neutral and grounding conductors, respectively. I totally buy that spare conductors need to be counted when conductors that can't be simultaneously energized are not counted, since the latter is a known factor whereas the former by their nature is an unknown factor and therefore needs to be assumed to be energized simultaneously as all the others.
 
texie said:
As for the second part of your question, installing an EGC on the supply side of a service disconnect would be a violation as it will be in parallel with the grounded conductor due to required bonding of the neutral at the POCO transforner by the NESC and bonding at the service disconnect required by the NEC.
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Sound logic...
Thank you all for the input.
 
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