Pulling large AWG wire

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Zee

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I gotta run the combined AC output of 3 inverters up and over a roof 50' and at least 4 @ 90 degree bends to the ACD.
Would you, instead, run the individual INV output circuits (6 @ #3 THWN-2 CU hots plus neutral plus EGC) then combine at end of above run next to ACD ?
or...........
combine inverter outputs at inverters then run the mongo 4/0 (250A circuit, so maybe 250 kcmil) to ACD?

Spaghetti = 1-1/2" EMT min.
Beefy wires = 2" EMT min.
 
Zee said:
I gotta run the combined AC output of 3 inverters up and over a roof 50' and at least 4 @ 90 degree bends to the ACD.
Would you, instead, run the individual INV output circuits (6 @ #3 THWN-2 CU hots plus neutral plus EGC) then combine at end of above run next to ACD ?
or...........
combine inverter outputs at inverters then run the mongo 4/0 (250A circuit, so maybe 250 kcmil) to ACD?

Spaghetti = 1-1/2" EMT min.
Beefy wires = 2" EMT min.
Click to expand...
I would run them in individual conduits to the AC combiner next to the disco. Three easy pulls rather than one hard one.
 
Zee said:
Why AL? cost ....weight....
is AL stiffer than CU?
Click to expand...

Believe it or not, Cu is stiffer than AL. Surprising, when aluminum is a lot more common in structural applications, and copper as a structural material is something you rarely see. The advantage of aluminum as a structural material has to do with aluminum alloys' strength to weight ratio, rather than its stiffness.

The properties that indicate the stiffness in bending loads are Young's modulus and second moment of area (aka "area moment of inertia"). Young's modulus is the one that is a function of material identity, and the other property is a property of the section's geometry. Aluminum's Young's modulus is 68 GPa, and for copper, it is 130 GPa. This means copper is about twice as stiff as aluminum, given an identical shape for both of them.
 
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