Voltage drop

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genesparky

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Kingman Az.
Can someone please direct me to the section/table of the 05 codebook that addresses voltage drop? I have to feed a weather station 220 feet from the panel. Very little current, 30 watts but I want to make sure I have 120 volts when I get there. I read 210.19 and 215.2 but I am not seeing where that tells me what size wire to run.
Thanks in advance
 
the code only stipulates the maximum allowable voltage drop on feeders and branch circuits. remember, voltage drop is a function of current -- 30 watts has a very little current draw. use the voltage drop formula not found in the code book, and find out what you can expect --- i don't think you have a problem...............................
 
voltage drop has to be calculated VD=2KIL/CMA, or something like that. That will give you a number of volts, then you must determine what percentage of your required amps that number is.
 
charlie tuna said:
the code only stipulates the maximum allowable voltage drop on feeders and branch circuits. remember, voltage drop is a function of current -- 30 watts has a very little current draw. use the voltage drop formula not found in the code book, and find out what you can expect --- i don't think you have a problem...............................
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With the exception of fire pumps I don't believe that the NEC has any requirement for voltage drop. Just a few FPN's which are not mandatory. Having said that I wouldn't worry about a 30 watt load. You can check here if you like:

http://www.electrician2.com/calculators/vd_calculatoradv.htm
 
Bill W said:
voltage drop has to be calculated VD=2KIL/CMA, or something like that. That will give you a number of volts, then you must determine what percentage of your required amps that number is.
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For me a better formula would be Cm = 2K x L x I / Vd.
Vd is 3% of whatever voltage you have for branch circuits and 5% for total.
This will tell you what size wire or Circular mills you need for a given load


So you would have Cm=25.8x220x.25/3.6
Cm=394.16
18 awg has a circular mill of 1620
So 14 or 12 awg will work all day long
 
Vd is 3% of whatever voltage you have for branch circuits and 5% for total.
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Although this is mentioned as an FPN within the NEC it is not a code requirement.
 
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