Originally Posted by klkanders
Right On Gregg and James! Good Advice
Joey If I make it to AZ lets have a Fat Tire or two!
James..I would be thrilled if you could explain to us how you would prevent VD from effecting a light 100ft away and only a 12v tap. Please enlighten us??
Lets just say that Matt here on one run is using 20w lamps. He has 4 20w lamps on a 12/2 cable. 20X4=40 divided by 12 (voltage)=6.67amps
So our VD method is as follows:
Distance X 2 (AC there and back) 200ftX.00162(12/2 resistance)X Amps
200 X .00162 X 6.67 = 2.161 volts of drop.
That means it would require a 14v tap to get 12v out to his lights
Now we can do the same thing for 10/2 wire. Resistance is .00108
8/2 wire Resistance is .00064
10/2 is 1.44 Volts of Drop requires a 13v tap
8/2 is .854 Volts of Drop still would require a 13v tap.
Next you have to discuss the wiring layout. More than likely this is a daisy chain, so you will have continues drop. Light closes to TF will be burning nice and bright the lamps further down the line will still be dim.
So you can argue 8 guage wire, but at that point you may as well buy a decent TF. I dont know off hand how much 8/2 costs but it has to be well over $.60 per foot?
On top of that once you put a load on that TF that 12v tap is no longer 12v.
Now maybe I am missing something but I have a pretty hard time believeing that you can go 100ft with 4 lights with only a 12v tap and still get 12v to your lamps.
Matt, if you do want to upgrade to a new unit I would be more than happy to tell you exactly what you need to do here. But maybe James has a magic trick that will not require you to spend any more money.