Quote:
Originally Posted by greif
Low voltage needs big wire, been a long time since I took the solar classes. Just like you have big cables on your 48 v citicar
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My thoughts exactly. So, I put Ben's scenario into a DC voltage drop calculator I found through Google search. I would definitely look for larger wire Ben. Voltage drop calculations yielded the following results:
Voltage drop:
4.04
Voltage drop percentage:
8.42%
Voltage at the end:
43.96volts
I used the following inputs:
Copper Conductors
AWG:
14
Voltage:
48
AC/DC:
DC
# of conductors:
single set
Distance:
100'
Load Current:
8A
I presumed 50 feet out to the load, and 50 feet back to the panel, thus I have 100' of wire for the moving electrons to traverse.
Idealy, something #6AWG or larger would yield results like this:
Voltage drop:
0.63
Voltage drop percentage:
1.31%
Voltage at the end:
47.37
Usually, you want to keep your voltage drop under 2%, because it's just wasting energy. Again, my numbers are all relative to a 100 ft wire run. I don't know what your run distance really will be from the panel, through the conduit to your load and back to the panel.
The reason you can run 15A through #14AWG in a house is because you are running Alternating Current. Direct Current is much worse about voltage drop. That was actually one of the motivating factors in my use of micro-inverters: short DC run, then converted to 240V AC to get from the roof to the service entrance panel.