austin.colby 0 Posted January 11, 2014 Hello, I need to run power to a camera and a wireless repeater that is about 1100' away from the house. Both devices use combined about 20w nominal which to me would seem to be about 2 amps overall. It seems that if I use a 14awg wire over 1100 feet with a 24v transformer, the voltage would be about right where I need it. I'm just not sure how to calculate the amperage drop and also the correct transformer size. Any help would be greatly appreciated. Share this post Link to post Share on other sites
varascope 0 Posted January 12, 2014 I would recommend using a 28vac transformer. What is your total draw on the remote devices? 28vac at 1100ft with 14awg you will have 22.4 vac at end with a 1Amp Load. Share this post Link to post Share on other sites
varascope 0 Posted January 12, 2014 If it is true that you need 2amps (Seems high) You would need 36vac to pull off 24.89vac at the end. Found this on Ebay $25 MCI Limited Transformer 200-36-120E 115-36V @ 5 Amp NEW Share this post Link to post Share on other sites
aussiephil 0 Posted January 13, 2014 Hi, Brand new to this forum and probably one of the very few topics here that i'm qualified to chime in on. Long experience runing Low Voltage DC lighting. Please do not rely on voltage drop on the cable to provide the final end voltage as the no load voltage will be way out of spec and any additional draw will cause excess voltage drop. I would inject 36v DC at the source and then use a DC-DC convertor to drop it to 12V at the far end, this is a common one from ebay. http://www.ebay.com.au/itm/DC-DC-Converter-Regulator-8V-40V-Step-Down-12V-3A-36W-/280735822879?pt=AU_B_I_Electrical_Test_Equipment&hash=item415d28b41f#ht_2773wt_1124 48V input ones are available as well just a bit harder to find. Doing to it this way will mean about 800mA of draw on the 1100' run leading to a better more stable DC voltage at the far end due to the DC-DC convertor. Cheers Phil Share this post Link to post Share on other sites
SectorSecurity 0 Posted January 18, 2014 You have to remember DC and AC are not interchangeable, you can't use a 28V AC adapter to supply power for 12V DC. Share this post Link to post Share on other sites
ak357 0 Posted January 18, 2014 You have to remember DC and AC are not interchangeable, you can't use a 28V AC adapter to supply power for 12V DC. Sure u can few diodes,regulator,few resistors,caps,heat sink and u done Share this post Link to post Share on other sites
