Street Light VD

[HoosierSparky]

I am having mental lock up. I have a 550ft run of #12 for about 10 led lights. lights have a load of about 15 watts. When I calc out the voltage drop, do I use the entire load or calc it out where I drop load after each fixture?

 

[drcampbell]

Start simple: Lump the entire current draw at the far end and calculate the voltage drop as if it were one load. (my calculation came to 2.75 v) If that's acceptable, there's no need to calculate more precisely.

To calculate more precisely, divide the string into discrete segments and calculate the current & voltage drop in each one. The voltage drop for each fixture is the sum of all the voltage drops upstream of it. Since the calculations are highly repetitive, a spreadsheet will come in handy.

 

[Besoeker]

Start simple: Lump the entire current draw at the far end and calculate the voltage drop as if it were one load. (my calculation came to 2.75 v) If that's acceptable, there's no need to calculate more precisely.

To calculate more precisely, divide the string into discrete segments and calculate the current & voltage drop in each one. The voltage drop for each fixture is the sum of all the voltage drops upstream of it. Since the calculations are highly repetitive, a spreadsheet will come in handy.

I agree. It's the simple but conservative approach.

 

[Phil Corso]

I am having mental lock up. I have a 550ft run of #12 for about 10 led lights. lights have a load of about 15 watts. When I calc out the voltage drop, do I use the entire load or calc it out where I drop load after each fixture?

Hoosier,

If loads are equal-spaced then search Archives for "V-Drop Calc for Evenly Spaced Loads"! If not, Calc can be modified for different loads and different spacing!

Phil Corso