voltage drop ?

[papa]

18 fixtures with .5 amp ballast at 120 volt, 300 feet total run, #12 wire . What will voltage be at end of run? Would this installtion be ok?

 

[iMuse97]

Are the fixtures located at various distances along this run, or all at the end of it?

 

[papa]

First one is at 100 feet from panel , then space about 10 feet apart.

 

[jumper]

Voltage drop calculator.

http://www.mikeholt.com/documents/freestuff/other/VoltageDropCalculator.xls

 

[papa]

Voltage drop calculator.

http://www.mikeholt.com/documents/freestuff/other/VoltageDropCalculator.xls

I have trouble calculating voltage drop when all load is not at the end.

 

[jghrist]

I have trouble calculating voltage drop when all load is not at the end.

You have to calculate one section at a time. This is a problem if you're using Mike Holt's calculator because it doesn't calculate voltage drop, it calculates what size wire, what length, or what current you need to get a specific % voltage drop.

 

[kingpb]

Be conservative and just assume all the load is at the end. The amount of time you save will be well worth it.

 

[broadgage]

A good approximation, when equal loads are spaced equaly along a circuit is to assume that all the load is at the mid point of the section containing the load.

For example, 36 lights spaced equally along 100 yards, presume that all the load is at 50 yards.
If there is another 100 yards of cable between the source and the first light, then presume that all the load is at 150 yards from the source.

 

[George Stolz]

Agreed. No problem.