Landscape lighting - Why is one run dim?
Question:I have a 600 watt transformer with one 150' run & one 200' run w/a total of 320 watts, but the 200' run is dim. Why? The transformer is supposed to accommodate two 200' runs. Would a bigger transformer fix the problem?
Answers:
Because the resistance increases with the length of wiring, if you are going to run longer runs you may want to move up to a larger size wire for this run - larger diameter will have lower resistance.
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I am assuming you are running the Xfmr off of house wiring 120V, so that means :
600w / 120V = 5 Amps.
therefore, I cannot see lights using this much current which means, a larger transformer will probably not solve the problem.
You say you "have" 320 watts total, so that is 320/120 = 2.66 Amps and your transformer can handle 5 amps on this voltage. So again, a largr Xfmr will not resolve this issue. It has to do with the resistance, i believe.
More resistance = less current can travel.
Less current travelling = less current going through each bulb; thereby, reducing their illumination ( brightness).
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Don't forget also, electricity will seek out the path of least resistance. Despite the longer run and higher resistance you have to look at the other run as well. It has less resistance because its length is less; therefore, more current will take this path and cause these lights to consume more than the others, and their brightness will be greater, as well.
For me, I would make sure the two runs are even ( within a few inches but less than a foot).
If you know the guage of wire used in both, you can calculate your resistance for each run. Now you can try larger guage sizes for the longer run so that the resstance for that run will come very close to the resistance for the smaller run. you want equal resistance if you are running them parallel like you describe.
if that is not possible then you want to run them serially so they all have the same current - same illumination. So maybe you can connect one run into the other this will even things out also.
I do not believe it is voltage drop because if this were the case then the first light on the string would be bright and begin to get progressively dimmer the further down the string you go - plus you would see the same effect on the other string of lights too, but it is not the case, it is one entire string is dimmer than the other.
Also, when buying an Xfmr in the future be sure to look at " continuous " and not "max" if this is rated at 600 watts max, that is not what it is able to supply continuously, just so you know.
Assuming your connections are all good, I think the problem is voltage drop. Every length of wire, as well as every light consumes energy. The longer line (with more lights?) has more voltage drop than the shorter one. A larger transformer may help, the one you have sounds borderline to me.
FIRST CHECK THE LAMPS IF ONE IS A HIGHER WATTAGE THIS WILL CAUSE THE LIGHTS TO DIM.IF YOU REMOVE THE WORKING STRING OF LIGHTS DOES THIS CURE THE PROBLEM?. IF THE DIM STRING WIRES ARE OF A LESSER CROSS SECTIONAL AREA THAN THE WORKING STRING THIS TO MAY CUSE THE PROBEM. COUNT THE TOTAL NUMBER OF LIGHTS ON BOTH STRINGS ADD THE COMBINED WATTAGE THEN DIVIDE THE OUTPUT VOLTAGE INTO THE COMBINED WATTAGE IF THE ANSWER IS LESS THAN 600WATTS THEN THEY SHOULD WORK IF THE ANSWER IS OVER 600 WATTS THEN YOU NEED TO GET A BIGGER RASFORMER
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