Wireway Conductor Fill

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Rodney Callen

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For Wireway conductor count. Would a divider create 2 separate cross sectional areas allowing for a count of 30 conductors below and a count of 30 conductors on top before derating? This is referenced from 362-5 1999 book
 
Rodney Callen said:
For Wireway conductor count. Would a divider create 2 separate cross sectional areas allowing for a count of 30 conductors below and a count of 30 conductors on top before derating? This is referenced from 362-5 1999 book
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IMO yes but others here may feel differently.

Welcome to the Forum. :)
 
as a footnote, I spoke to Hoffman about this topic of dividers and in their words, "the intent of the dividers is to build out a path for the option to run & separate High and Low Voltage wiring.
 
jcassity said:
as a footnote, I spoke to Hoffman about this topic of dividers and in their words, "the intent of the dividers is to build out a path for the option to run & separate High and Low Voltage wiring.
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That still doesn't answer the question of the thermal issue about which our OP asked.
 
Rodney Callen said:
For Wireway conductor count. Would a divider create 2 separate cross sectional areas allowing for a count of 30 conductors below and a count of 30 conductors on top before derating? This is referenced from 362-5 1999 book
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I would say no, IMO. The point of a divider is the use of different wiring methods within the same wire-way, not to bypass the requirement of 30 conductors in any cross section area, again JMO.
 
jusme123 said:
I would say no, IMO. The point of a divider is the use of different wiring methods within the same wire-way, not to obfuscate the requirement of 30 conductors in any cross section area, again JMO.
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It seems silly to me that two wireways physically mounted together would be any different than one wireway with a divider given that in the end they both had the same cross sectional area.
 
infinity said:
It seems silly to me that two wireways physically mounted together would be any different than one wireway with a divider given that in the end they both had the same cross sectional area.
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...it also seems silly to require pull points in 4" conduit run with 4-600's, knowing they will not be used as a pull point (wired pulled strait thru), but satisfy the 360 degree NEC requirement.
 
jusme123 said:
...it also seems silly to require pull points in 4" conduit run with 4-600's, knowing they will not be used as a pull point (wired pulled strait thru), but satisfy the 360 degree NEC requirement.
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I've always wondered about the 360 degree requirement. I know it is sort of a one-size-fits-all rule, covering typical conduit lengths, and usually works as a guideline to keep you out of trouble when constructing conduit runs.

However, I would think that if the pulling metrics are low enough to indicate a "gentle pull", even with a lot more than 360 degrees worth of bends, I would think there would be no problem with building it, and having it work. What I mean by pulling metrics, is the tension and sidewall pressure. I'm sure you can come up with examples where one could in concept exceed the 360 degree rule, and still have a successful installation.
 
Carultch said:
I've always wondered about the 360 degree requirement. I know it is sort of a one-size-fits-all rule, covering typical conduit lengths, and usually works as a guideline to keep you out of trouble when constructing conduit runs.

However, I would think that if the pulling metrics are low enough to indicate a "gentle pull", even with a lot more than 360 degrees worth of bends, I would think there would be no problem with building it, and having it work. What I mean by pulling metrics, is the tension and sidewall pressure. I'm sure you can come up with examples where one could in concept exceed the 360 degree rule, and still have a successful installation.
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...that is done every day in this trade, especially if SimPull is used
 
A single box with a divider becomes two boxes from a code perspective, why wouldn't a divider in a wireway become the same? Listing issues aside, if we accept that the NEC is a permissive code then what explicitly would prohibit the use of a divider in a wireway to make two wireways?
 
infinity said:
A single box with a divider becomes two boxes from a code perspective, why wouldn't a divider in a wireway become the same? Listing issues aside, if we accept that the NEC is a permissive code then what explicitly would prohibit the use of a divider in a wireway to make two wireways?
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Maybe you have to maintain spacing between them?
:angel:
 
2014 edition....

2014 edition....

I'm curious if 310.15(a)(2)EX trumps 376.22(b)

Exception: Where two different ampacities apply to cuUa-
cent portions of a circuit, the higher ampacity shall be
permitted to be used beyond the point of transition, a dis-
tallce equal to 3.0 m (10 ft) or 10 percent of the circuit
length figured at the higher ampacity, whichever is less.
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376.22(B) Adjustment Factors. The adjustment factors in
310.15(B )(3)( a) shall be applied only where the number of
current-carrying conductors, including neutral conductors
classified as current-carrying under the provisions of
310.I5(B)(5), exceeds 30 at any cross section of the wireway.
Conductors for signaling circuits or controller conductors be-
tween a motor and its starter and used only for starting duty
shall not be considered as current-carrying conductors.
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~RJ~
 
romex jockey said:
I'm curious if 310.15(a)(2)EX trumps 376.22(b)

~RJ~
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The 10ft/10% exception applies to any reason why the ampactiy would be less, in the smaller portion of the length, given that it is still the same conductor. This doesn't include 75C rated terminations on 90C wire, but for all other reasons why ampacity would be less, it applies.

One example is stubs on a rooftop, where most of the run is inside the building, but this small portion is in direct sunlight and thus has an elevated ambient temperature.

Another example is if you have a wireway distributing wires among numerous pieces of equipment, and the final piece of equipment adds your 31st current carrying conductor. Yet for all the other equipment served by this trough, this is less than 10% of the total conductor length and less than 10ft total.

A blindspot to this rule is whether or not you are allowed to "double dip" it. Consider two portions of reduced ampacity, on opposite ends of the circuit, each individually less than 10%/10ft, but perhaps greater than this length limit collectively. Another blindspot is whether or not this only applies to continuous factory lengths of wire, or if you are allowed to splice it to an identical type of wire and still count the length.
 
Carultch said:
I've always wondered about the 360 degree requirement. I know it is sort of a one-size-fits-all rule, covering typical conduit lengths, and usually works as a guideline to keep you out of trouble when constructing conduit runs.

However, I would think that if the pulling metrics are low enough to indicate a "gentle pull", even with a lot more than 360 degrees worth of bends, I would think there would be no problem with building it, and having it work. What I mean by pulling metrics, is the tension and sidewall pressure. I'm sure you can come up with examples where one could in concept exceed the 360 degree rule, and still have a successful installation.
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How many people can calculate raceway or wireway fill as well as do ampacity adjustments where required, but don't know how to go about calculating "pulling metrics"?

NEC doesn't cover those "pulling metrics" either.
 
kwired said:
How many people can calculate raceway or wireway fill as well as do ampacity adjustments where required, but don't know how to go about calculating "pulling metrics"?

NEC doesn't cover those "pulling metrics" either.
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My point is that if you place 5 factory 90 degree elbows end-to-end, it is still possible to pull the wire, probably even by hand. And this would be a violation by the letter of the code, even though the real life consequences are non-existent.

I'm aware that this is an unlikely case to encounter in real life, as most situations will have significant enough length between the bends, that the 360 degree rule is still a good "one-size-fits-all". Southwire makes a spreadsheet to calculate the pulling metrics of sidewall pressure and tension. And keeping track of this information is an important part of the puzzle of designing conduit runs.
 
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Carultch said:
My point is that if you place 5 factory 90 degree elbows end-to-end, it is still possible to pull the wire, probably even by hand. And this would be a violation by the letter of the code, even though the real life consequences are non-existent.

I'm aware that this is an unlikely case to encounter in real life, as most situations will have significant enough length between the bends, that the 360 degree rule is still a good "one-size-fits-all". Southwire makes a spreadsheet to calculate the pulling metrics of sidewall pressure and tension. And keeping track of this information is an important part of the puzzle of designing conduit runs.
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I understand that and have pulled more then 360 degrees of bend before, did not make it any more or less code compliant though.;)
 
Carultch said:
Southwire makes a spreadsheet to calculate the pulling metrics of sidewall pressure and tension. And keeping track of this information is an important part of the puzzle of designing conduit runs.
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Very very few electrians do any pulling calculations when installing conduit runs. It's simply not done.

I have done it once when I asked an EE if I could reduce the size of the conduits he had specified. The response was yes, if I provided pulling calcultions that showed no problems in doing so.
 
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