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04-30-2009, 05:43 PM
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#1
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Pro
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Artistic Outdoor Lighting
Join Date: Jul 2007
Posts: 107
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A Couple NEC questions
As a low voltage landscape lighting professional I rarely need permits so I don't know the NEC very well. I have 2 questions I would appreciate you guys helping me out on:
1) Can you have more than 3 currents carrying conductors in a raceway without derating them the 80%?
2) What is the max lenght of conduit you can run without de-rating?
Thanks
~Ned
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04-30-2009, 05:55 PM
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#2
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Electron Flow Manipulator
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Location: Iowa
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Quote:
Originally Posted by NightLightingFX
.......1) Can you have more than 3 currents carrying conductors in a raceway without derating them the 80%?
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If you meet any of the exceptions to 310.15(C)(2)(a), you can.
Quote:
Originally Posted by NightLightingFX
2) .......What is the max lenght of conduit you can run without de-rating?.........
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There is no maximum length when it comes to derating. Raceway length is only limited by how long you can get conductors, and your method to pull them in.
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04-30-2009, 07:48 PM
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#3
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Electrical Contractor
Trade:
Electrical
Join Date: Sep 2003
Location: NY State
Posts: 1,952
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Quote:
Originally Posted by NightLightingFX
1) Can you have more than 3 currents carrying conductors in a raceway without derating them the 80%?
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What type and size of conductors?
If you are working with #14, #12 or #10 then you should not have to worry about derating until you reach NINE CCC's.
Remember, the neutral of a MWBC is not counted as a CCC with regard to derating.
I am curious. What do permits have to do with knowing the codes related to your trade?
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04-30-2009, 09:14 PM
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#4
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God Bless America
Trade:
Electrician
Join Date: Dec 2006
Location: Rahway, New Jersey
Posts: 3,400
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480, I think what the OP was asking about as far as the maximum size length conduit before needing to derate would be 24".
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04-30-2009, 09:24 PM
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#5
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Electron Flow Manipulator
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Quote:
Originally Posted by Magnettica
480, I think what the OP was asking about as far as the maximum size length conduit before needing to derate would be 24".
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I think you're right about the nipple length, but that would be 600 mm, not 24 inches. 
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04-30-2009, 09:45 PM
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#6
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God Bless America
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Oh, lol. Is that what 310.15(C)(2)(a) says? I don't have my book in front of me and I'm in the middle of filing some crap with the my new business partner the IRS.
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04-30-2009, 10:17 PM
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#7
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Electron Flow Manipulator
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Quote:
Originally Posted by Magnettica
Oh, lol. Is that what 310.15(C)(2)(a) says? I don't have my book in front of me and I'm in the middle of filing some crap with the my new business partner the IRS.
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No, that comes from Chapter 9, Note 4.
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05-01-2009, 10:07 AM
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#8
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Pro
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Join Date: Jul 2007
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Thanks for the response guys I appreciate it. 
~Ned
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05-01-2009, 12:22 PM
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#9
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ampman
Trade:
providing pathways for electrons and protons
Join Date: Apr 2009
Location: central florida
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i thought the 24" nipple rule was for conduit fill not conductor derating
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05-01-2009, 02:16 PM
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#10
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God Bless America
Trade:
Electrician
Join Date: Dec 2006
Location: Rahway, New Jersey
Posts: 3,400
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Quote:
Originally Posted by ampman
i thought the 24" nipple rule was for conduit fill not conductor derating
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Good question.
310.15(B)(2)(a) Exception No. 3: Derating factors shall not apply to con-
ductors in nipples having a length not exceeding 600 mm
(24 in.).
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05-01-2009, 03:23 PM
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#11
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Electron Flow Manipulator
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Quote:
Originally Posted by Magnettica
Good question.
310.15(B)(2)(a) Exception No. 3: Derating factors shall not apply to con-
ductors in nipples having a length not exceeding 600 mm
(24 in.).
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As well as Ch. 9, Note 4:
(4) Where conduit or tubing nipples having a maximum length not to exceed 600 mm (24 in.) are installed between boxes, cabinets, and similar enclosures, the nipples shall be permitted to be filled to 60 percent of their total cross-sectional area, and 310.15(B)(2)(a) adjustment factors need not apply to this condition.
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05-01-2009, 09:00 PM
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#12
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ampman
Trade:
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Join Date: Apr 2009
Location: central florida
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so its settled no derating of conductors in conduit 24"(600 mm) or less and fill @ 60 % for two conductors and over
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05-01-2009, 09:02 PM
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#13
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Electron Flow Manipulator
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Quote:
Originally Posted by ampman
so its settled no derating of conductors in conduit 24"(600 mm) or less and fill @ 60 % for two conductors and over
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I second that.
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05-01-2009, 09:02 PM
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#14
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ampman
Trade:
providing pathways for electrons and protons
Join Date: Apr 2009
Location: central florida
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Quote:
Originally Posted by Magnettica
Oh, lol. Is that what 310.15(C)(2)(a) says? I don't have my book in front of me and I'm in the middle of filing some crap with the my new business partner the IRS.
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they are a silent partner unless dont pay
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