# DC lighting transfromers

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#### dicklaxt

##### Senior Member
Thanks ,I got it now,a very well thought out explanation.

dick

#### LarryFine

##### Master Electrician Electric Contractor Richmond VA
. . . as you can see this ring is fed to both sides of the ring, and the voltage and resistance will be equal around this ring circuit, . . .
But, wouldn't those lights nearer the transformer's side of the circle still be brighter?

I like Gar's method, which, as a circle, would be just like yours, except that one ring would have a break just clockwise of the transformer, and the other would have a break just counter-clockwise of it.

In other words, the lights are supplied via a typical single parallel pair of wires, except one wire gets fed at the end closest to the supply, and the other, via a third wire, at the far end.

This way, every light receives the same voltage, regardless of overall circuit length.

#### dicklaxt

##### Senior Member
Now that I have been introduced to this circuitry,I ask myself why this is not used in plain vanilla 120VAC lighting.I guess when VD is not a problem the cost of the 3rd conductor is a total waste but when VD is a problem then the added cost of the 3rd wire would be accepted.I guess at this point a comparison of calculating VD to the load center and upsizing conductors as needed is a wash.It would be interesting to see where the break even point was with all factors stirred in.

dick

#### WinZip

##### Senior Member
Dick,

What voltage would you need to send through the entire 400 foot loop to make this work , and wire size.

12 - 13 -14 - 15 -16 - 17 volt

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#### dicklaxt

##### Senior Member
That would take a bit of calcs but doable,I would first divide the wattage of the lamp by a desired voltage to determine the current,then with that known value I could solve a second equation and determine the resistance of the lamp,you can now substitute different voltage levels and solve for current at that voltage,do a summation of current in resistors in parallel to get total load at a given voltage,then using that solve for VD allowed for the threshhold voltage, which would be the acceptable voltage required to give you a satisfactory light output.A lot of basic Ohm's Law math.

I think I said that right,if not someone will correct it LOL'

dick

#### WinZip

##### Senior Member
No offense but that seems like a lot of thinking an calculating to make that set up work, then you have the person that comes back years later working on it an he is baffled LOL

#### dicklaxt

##### Senior Member
No offense taken but you asked,LOL,,,,,,,, your need has a mutitude of variables.

dick

#### WinZip

##### Senior Member
I'm not the original poster LOL

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