Kapkirk Posted October 31, 2017 Share Posted October 31, 2017 I know the answer is out there but failed to find it in search and google just tried to sell me something/everything. I want to power and control about 100 feet of LED C6 light strands, guess about 3 100 bulb strings, HLE website says you can connect 27 strands end to end, so can I assume I could power and control those 3 light strands from say 400 feet from the LOR controller using spt-1? We are currently using ELL's to control 32 channels for our singing xmas trees and don't have any spare channels, and my neighbor doesn't want to use one 16 channel controller for just the one channel needed so I was thinking I could use a spare channel from one of my 3 Mega tree controllers to control the 3 light strands on his roof. I am only using 45 channels of the 48 so sequencing will be easy enough to do. Appreciate any thoughts on the maximum distance SPT will power LED light strands. Keith Link to comment Share on other sites More sharing options...
dibblejr Posted October 31, 2017 Share Posted October 31, 2017 My front yard is 160' from where I normally place my controller for those lights, I have no problems but they are mini trees. SPT-2 is what I use for everything. JR Link to comment Share on other sites More sharing options...
George Simmons Posted October 31, 2017 Share Posted October 31, 2017 I'd prefer a 16 ga wire over an 18ga wire, but you should be okay. Test it to confirm. Link to comment Share on other sites More sharing options...
caniac Posted October 31, 2017 Share Posted October 31, 2017 8 hours ago, George Simmons said: I'd prefer a 16 ga wire over an 18ga wire, but you should be okay. Test it to confirm. what he said!! Link to comment Share on other sites More sharing options...
Kapkirk Posted October 31, 2017 Author Share Posted October 31, 2017 Thanks guys, appreciate all your help. Sleeping on it I am thinking I would rather put one of my spare controllers over there and control the channel that way, and I can assign it the same number as my controller and use more channels for future use. Thanks, Keith Link to comment Share on other sites More sharing options...
k6ccc Posted October 31, 2017 Share Posted October 31, 2017 You are fine. Here's the math to back up the statement: I looked up specs for several 100 count LED strings and found an average wattage of about 7 watts. So three strings would be 21 watts. With a 120 volt source and a 10 volt drop considered an acceptable voltage drop resulting in 110 volts to the LEDs. With 110 volts to the LEDs and a 21 watt load, that results in a current of .191 Amps. With .191 Amps and an acceptable voltage drop of 10 volts, results in an acceptable resistance of the power line of 52.36 Ohms. 18 AWG copper has a resistance of 6.385 Ohms per 1000 feet, so to get 52.36 Ohms would require 8,199 feet of 18 AWG copper wire. Since the power has to go out in one wire and come back in another wire, that means you can go half that distance - or 4,099 feet. 1 Link to comment Share on other sites More sharing options...
Kapkirk Posted October 31, 2017 Author Share Posted October 31, 2017 K6ccc Thanks, you went way past ohm's law to figure all that I am guessing. Reciprocating engine mechanic here, in the old days if it had a wire attached to it we would call for an electrician. That will help a bunch of us non electrical engineers in future I am betting. Thanks, Keith Link to comment Share on other sites More sharing options...
k6ccc Posted October 31, 2017 Share Posted October 31, 2017 1 hour ago, Kapkirk said: Thanks, you went way past ohm's law to figure all that I am guessing. No, pretty much just Ohms law and a reference chart of wire resistance. There are lots of the latter around, but here is the one I have bookmarked: http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.html 1 Link to comment Share on other sites More sharing options...
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