# Connecting two power supply {LED Light 12v}

I have 6 strip of lights consisting of approx 100ft total.

1 strip = 16.5ft , 36w, 150 leds, 12v, 3a .. and can be connected to total of 20 strips end-to-end.

It will be controlled by an RF controller at one end to display patterns, etc and the controller will be powered independently. Each strip is connected to the next strip, and on each's end have an extension female power adapter to get more power of its own to be used to its fully lighting potential.

I have a 20a 12v power supply on hand which I'd like to use to power these, however, I like to know if I center that power supply at 50ft in middle and run the wires from center outwards 50ft to left and 50ft to right would that be sufficient? Wires would be 12guage electrical copper wire I have 200ft spool of that I don't use.

-or-

Should I get another 20a 12v power supply, totalling two, and place one on each end so as not to drop the current load? I ask this because I was given a theory of seeing this as 100ft hose and the pressure would drop the more it is extended whereas the most pressure (light output) would be that nearest to the power supply. So by having one and both end they would push to each other and no current would drop. And each of the female adapter would be fed into the 12guage male that I would attach too this additional power.

You don't want to hook 20 strips end-to-end unless they're making the strips out of much stronger stuff than the ones I have. Passerby described the math to it. If you fed three strips from one end of one strip, I wold not be surprised if it burned up the PC traces.

I would run a parallel "bus" and feed strips from both ends. In Code electrical, 100' is about where voltage drop hits 3% and you want to bump to the next larger wire size. Keep in mind 3% voltage drop at 120V is a 30% voltage drop on 12V! Plug it into a voltage drop calculator and it will do the math. But the numbers get real scary real fast with 12V at 100'. I asked the calc to show me 12V at 3% voltage drop, and it recommend 3/0 wire (or preferably, 250kcmil aluminum, which is 1/2" diameter). The wire would be bigger than your whole LED strip!

Now over on diy.se, taking a fat-wire problem and solving it with the thinnest legal wire (14 AWG) is pretty much my "hat". Here we go:

One way to solve the long-distance voltage drop problem is to distribute the 12V power supplies along your 100' so you're carrying 120V/230V the long distance instead of 12V. When you double voltage you quarter losses, when you 10x voltage you 1/100x losses. 14 AWG wire would suffice! tips hat

This is how light-rail lines do it, they don't carry 600V from Long Beach to Pasadena, they carry 24,000 volts AC and have a 600V substation every 3-5 miles.

The biggest source of voltage drop is the copper FPC that the strips are made of. 12 AWG has 0.0016Ω per foot of resistance. Even 100 ft is only 0.16Ω. LED strip copper tape has a resistance of 0.0625Ω per foot. 1 ohm for 16 ft. HORRIBLE resistance for high current. Typically, you want to power a single 5 meter (16.5 ft) strip from the middle. Multiple strips at each 5 meter end.

You have two options.

1. Run the 12 gauge wire parallel to the 100 ft of led strip, and tap each strip at 5m. Tap the 12 gauge wire at the center or both ends.

2. Run multiple sections of the 12 gauge wire, and combine them near the power supply. Depending on where your supply is, this may require more than 200 feet you have.

• I will try that however what if I can do the following, shown in pic. Each power extension is actually at 5m, so to tap it at your recommendation of 16.5ft is excellent as it's premade for that initially (aka external female power in pic) and I can tap in a male adapter. But would it be better if I gotten two 20a power supply and placed one on each end then with a 100ft wire running to each. <postimg.org/image/60clhnvsd> Sep 28, 2016 at 0:30