Why dont conduit fill apply

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In 800.110, why doesnt the conduit fill requirements apply to smaller communications cables (like phone wire). They have conductors like 22 awg or bigger. Just trying to broaden my understanding of this.

I know in real world scenerio you would leave plenty of room for your install. But an inspector could never 'hit' anyone over it if looked way overfilled.
 
its the amount of heat that can be generated, not the amount of room in the conduit. your low voltage stuff will probably not have enough current on it to cause heat.
 
stjohnbarleycorn said:
its the amount of heat that can be generated, not the amount of room in the conduit. your low voltage stuff will probably not have enough current on it to cause heat.
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The conduit fill rules are based on mechanical and physical issues and not on the amount of heat that is produced by the current flow in the conductors. The derating rules in 310.15(B)(2) address the heat issue.


The code is based on safety issues, pulling too many conductors into a raceway could damage the conductors and or the conductor insulation. This could be a safety hazard for power conductors, but apparently is not considered a safety hazard for Chaper 8 conductors.

It seems to me that the smaller conductors used for many Chapter 8 applications would be more easily damaged by an overfilled conduit than standard power conductors.
 
Aren't they usually a pair or a quad or more with in an overall jacket,if so I would be tempted to get the over all sq inches and use the 53% fill guide lines.

dick
 
don_resqcapt19 said:
The conduit fill rules are based on mechanical and physical issues and not on the amount of heat that is produced by the current flow in the conductors. The derating rules in 310.15(B)(2) address the heat issue.


The code is based on safety issues, pulling too many conductors into a raceway could damage the conductors and or the conductor insulation. This could be a safety hazard for power conductors, but apparently is not considered a safety hazard for Chaper 8 conductors.

It seems to me that the smaller conductors used for many Chapter 8 applications would be more easily damaged by an overfilled conduit than standard power conductors.
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I agree, I suppose if an inspector wanted to 'tag' an install, they could use the 'workman like manner' clause. Having tons of wire in a conduit that they are squeezing each other is not workman like.
 
thanks for the info, I thought that heat would play a factor in the amount of conductors allowed in a conduit, just as the size of hole and amount of conductors in a wood frame building?
 
It does, but the strange things is it is based on conductor count and not conduit size. You hit deratings at 4-6 conductors, 7-9 conductors, and 10 or more. If you have 10 #12 wires in a 3/4" conduit, they have the same reduced ampacity whether the conduit is 4" or 3/4".
 
Is an overfilled raceway with Chapter 8 cables in it a threat to life or property as mentioned in 90.1?

I think if overfilled and the pull tension is too much the cables could be damaged but this is not a threat to life or property in most cases, maybe in a 911 call center it is.
 
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