Wire sizing

[fabricator]

Oh I intend to put a line in the pipe.

[birdhouse]

fabricator-

pvc conduit is cheap in comparison to copper wire.  i would upsize my conduit since it is cheap, then run wires you think are close to large enough, then if they aren't you can easily add an additional set of #10s or something.  this gains you two thing.  1) you can go with cheaper wire, and if needed add more and delay the cost in the meantime.  2) larger conduit gives the wires more breathing room.  ever notice a brand new 200 amp service entrance on a house?  the wires coming out of the mast head are pretty big.  usually 4/0 aluminum.  then look at the powwer companies wires coming off the transformer.  they are really small in comparison.  it has been described to me as the "open air rule"  aka, the power companies wires are not in conduit so they can release heat very well, so can be undersized for the application.  it's not apples to apples, but larger conduit will allow more space for heat to dissapate and lower resistance.  

toms idea above about using a vacuum to pull a fluffy item and string through the conduit is a very good one.  way easier than a fish tape in my mind.  i've watched electricians use this technique on a 300 foot plus run.  worked well!  

birdhouse  

[bracken]

Common copper wire sizes and resistance

AWG    Max I *    Inch Dia    mm Dia    Ohms per 1000'      

22    0.918    0.025            0.644    16.46   

20    1.46    0.032            0.812    10.35   

18    2.32    0.04            1.024    6.51   

16    3.69    0.05            1.291    4.09   

14    5.87    0.064            1.628    2.57   

12    9.33    0.08            2.053    1.62   

10    14.8    0.101            2.588    1.02   

8    23.6    0.128            3.264    0.64   

6    37.5    0.162            4.115    0.4   

4    59.6    0.204            5.189    0.25   

2    94.8    0.257            6.544    0.16   

1    119    0.289            7.348    0.12   

This might help.

Bracken

[ghurd]

AL gets close to double.

Do not forget 150' out and 150' back.

G-

[fabricator]

Gurd, what does that mean?

[ghurd]

Aluminum wire has more resistance per foot than the same size copper.

DanB's #4 AL is 0.408 ohms per 1000'.

Copper #4 is 0.2485 ohms per 1000'.  #6 copper is 0.3951 ohms per 1000'.

Meaning if #6 copper is perfect, but you want to use AL because it is cheaper, need to increase the AL wire size to #4 AL.

The distance is half the wire run. Uh...?

The amps flow 150' from the mill to the battery and have 150' of losses,

then turn around and flow 150' back to the mill and have Another 150' of losses.

If the distance is 150', the wire loss is 300'.  150' of Pos plus 150' of Neg = 300'

Some specific purpose wire charts (like some solar wiring charts) figure this "out and back" loss, so need to read the text to see if "out and back" is included.

G-

[fabricator]

Ahhhh, I guess I never considered the + - cycles, thanks for the enlightenment.