URD ampacity

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domnic

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Electrical Contractor
Where in 2011 code can I find ampacity chart for aluminum URD direct burial ?
 
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Jraef

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Location
San Francisco Bay Area, CA, USA
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Electrical Engineer
URD (Underground Residential Distribution) is just 3 USE cables that are bundled together; usually 2 full size conductors and a neutral that is smaller, with the insulation jackets joined (like zip cord) in most cases. In the NEC it is going to follow USE rules.
 

augie47

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Location
Tennessee
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State Electrical Inspector (Retired)
As "URD" as such is not listed in 310.104 it is not accepted in this area on a NEC installation. Much of the URD I see is dual rate3d as URD/RHW and is considered RHW that can be direct buried
 

kwired

Electron manager
Location
NE Nebraska
As mentioned URD comes from "underground residential distribution" which originally maybe was "triplexed" conductors, but for a long time now has also been available in "quadraplexed" conductors as well.

Originally was also likely just "USE" conductors, now you find USE as well as dual rated USE/RHW. They are just pre-twisted into an assembly of multiple conductors that otherwise have individual conductor ratings.

More recent years one can even get other assemblies of commonly used conductor types such as THHN/THWN in an assembly of black, red, blue, white, green or brown, orange, yellow, gray, green. Sort of same thing - different conductor type.
 
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