2 low voltage transformers on 1 circuit?

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I got a 600W Malibu low voltage transformer powering my landscape lights. But some of the lights further from the transformer are not as bright. I only have a single 12 gauge wire with all the lights attached on it.
Can I attach another 300W transformer at the far end of the wire so that the lights there will be brighter?
I cannot really run another wire from the 600W transformer, since much of the wire run under concrete pathways and also my driveway.
Thanks
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On Fri, 2 May 2008 23:34:53 -0700 (PDT), " snipped-for-privacy@hotmail.com"

Cut the existing wire in between two lights, so 1/2 of the lights remain attached to the 600 watt transformer. Properly seal the cut ends so they don't touch and are protected from moisture. You could use 4 sealed direct burial wire nuts, for example. Then connect the new transformer to the far end to power the other 1/2 of the lights. Size the new transformer properly to handle the lights it is powering. It may not be 300 watts, as all the lights may not be the same wattage. Make sure you use heavy enough wire, and if you have a long run from the transformer (say 50 feet or more) get a transformer with taps so you can start with a slightly higher voltage to compensate for loss in the long wire. The better low voltage transformers have several taps for this purpose.
You can do this without cutting the wire if you get the phasing correct, but if you separate into two groups, you eliminate any chance of confusion now and in the future.
HTH,
Paul F.
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The total wattage of all the lights combined is about 380W. I think the contractor stringed them all on a single 12-2 wire. So the ones furthest away from the transformer is pretty dim. The ones closest to the transformer are pretty bright.
The total length of the cable is about 100'.
You mentioned that I may be able to attach another transformer at the far end of the run, but I just need to make sure I connect the positive polarity side of the wire to the positive side of the new transformer, and ditto for the negative side. But there was another person who mentioned that I should not do this.
I do have a spare 300W transformer that I can use on the far end, but I just like to make sure it would not cause a fire hazard by having 2 transformers powering the same circuit.
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You have 380 watts on a 600 watt transformer. You don't need another transformer, you need to increase the conductor size feeding the lights or split the lights between two separate cables, both coming from the same transformer. You cannot connect a second transformer to the low voltage side of the existing transformer, if that's what you had in mind. Tough as it may be, you need to run another cable and split the circuit
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What was said below is very true, but isn't it possible that it would be much less work by adding a booster transformer at or near the far-end ?
James
--------------------------------
You have 380 watts on a 600 watt transformer. You don't need another transformer, you need to increase the conductor size feeding the lights or split the lights between two separate cables, both coming from the same transformer. You cannot connect a second transformer to the low voltage side of the existing transformer, if that's what you had in mind. Tough as it may be, you need to run another cable and split the circuit
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The problem he has, is that he's pulling approximately 32 amps through a cable rated at 20 amps. Even if the buck-boost that you linked to would work, it would just be helping to cook the existing undersized wire

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could try tapping line as it crossed driveway and running a cable to the other end tapping it into the circuit there.
this should elminate much of the voltage drop.
he can also add a extra transformer but it should be on the same breaker the first transformer is, in case a breaker trips.
and should be in phase.
connect and try both ways after dark.
the one thatr looks best is in phase. out of phase will decrease briteness
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I would convewrt everything to LED lamps, savepower save money, save having to change this
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snipped-for-privacy@hotmail.com wrote:

If you have 120V at the far end, just split the wire. I thought the whole point of the exercise was that a driveway separated the lights from the source of power.
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Thank you all for your input.
I spent the morning today tracing the buried wires and found the junction where the single wire coming from the 600W transformer is split into different branches running to different areas of the yard. This junction is on the other side of the driveway from where the 600W transformer is located.
I think I have found a good place to relocate the 600W transformer so that it will be on the same side of the driveway as where this junction is. My plan now is to run two 8 guage wires from the relocated 600W transformer to this junction. Then let the existing buried 12 gauge wires run from there to each spot. It will be hard for me to change out the 12 gauge wires after the junction, since they cross walkways and etc. But from the transformer to this junction, I have a clear path... which is great news! The two 8 gauge wires will each handle 1/2 the yard. The total length of each leg is about 40' from transformer to the junction (8 gauge), and then another 40' from junction to each spot (12 gauge). Most of the light fixtures are after the junction.
By the way, I used my voltage meter to measure the voltage drop across the 2 wires coming out from the transformer. I had expected to see 12V across them, but I dont detect a voltage drop. But somehow it works... :) How do you measure the voltage at each spot of the run if I cannot even detect a voltage drop across the 2 wires at the transformer? Thanks for any tips....
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Use a volt meter. You shouldn't have any drop at the transformer, but with the lights on, testing across the two conductors, you should get drop the farther away from the transformer you go
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Bad news. If you merely shorten the distance from the transformer to the junction, without changing the wiring after the junctions, this would brighten all the lamps, so the downstream lamps will still be dimmer than the closer one. Nevertheless, it is a safety improvement to change out the overloaded 12 gauge wires. Perhaps your contractor would do this for free if you could convince him the wires are overloaded. Is he even a licensed electrician?

You wouldn't happened to be using a DC meter to measure AC voltage? "voltage drop" means a voltage on the same wire at the two ends, not the output of a transformer. The output of the transformer should be 12V, and the voltage drop on the wire from the transformer to the junction would probably be less than 1V on each leg.

So some of the light fixtures are before the junction?? By definition there has to be a junction for the light to connect to.

Home depot may have free classes in electrical wiring. You can then show the instructor your wiring plan and get his blessing.
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Do the transformers deliver AC or DC?
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Christopher A. Young
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You don't specify the total connected wattage, but #12 is only good for 20 amps and a 600 watt transformer can handle up to 50 amps. You can't connect another transformer to the existing wiring, but you can cut the existing wiring in half as Paul Franklin suggested, and either connect the second half to a new transformer, fed by a new underground line, or just run a new underground line back to the 600 watt transformer, assuming it's large enough
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sorry your confusing wattage of 2 different voltage ratings.
20 amps at 120 volts is 2500 watts.........
but ratings change at 12 volts........
in any case is it possible the lamps are older somehow?
try a new bulb in a dim location before rewiring.........
lamps dim over time, this may fix you up..
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sorry your confusing wattage of 2 different voltage ratings.
600 watts divided by 12 volts = 50 amps @ 12 volts. # 12 cable is 20 amp and doesn't change with the voltage
20 amps at 120 volts is 2500 watts.........
but ratings change at 12 volts........
in any case is it possible the lamps are older somehow?
try a new bulb in a dim location before rewiring.........
lamps dim over time, this may fix you up..
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snipped-for-privacy@aol.com wrote:

I got rid of all that. Switched to solar power.
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snipped-for-privacy@aol.com wrote:

20 amps is/are still 20 amps

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RBM wrote:

is filtered out) I only saw it quoted in another reply. Depending on the number of lamps, length of cable and wattage (current) of each bulb, voltage drops do occur as you go down the line. These lamps gobble quite a bit of power. You can solve the problem by using lower wattage lamps and/or heavier wire. You need to do the arithmetic of adding up the wattage of each lamp to see if it comes under the 600 watts the transformer provides. But, as someone replied, 600 watt is 50 amps. If you are using all 600 watts, you need huge wires (8 gauge or larger) to carry that load, or you need to split the load. In all, we need more info as to the number of lamps, wattage and cable lengths.
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Remove the first light and measure the voltage there. Then remove the last light and measure the voltage there. If there is not much difference (say less than 0.5V), it's not worth repairing. If the difference is greater than 2V, then you may want to do something.
Several solutions come to mind: replace the brighter bulbs with lower wattage bulbs, or replace all of them with LED based bulbs -- saves you electric cost too.
If the transformer is on one side of your driverway and the lights are on the other side, then rewire the lights on the other side into a star network instead of a bus network. But you'd be running a lot of wires. A compromise is to group several lights into one group, and link each group using a star connection. Use thicker wires for longer run.
Assuming your lights run on AC, you could insert a transformer before the last few lights to raise the voltage a little. Let's say the voltage dropped to 9V near the end, if you could find a transformer to raise 9V to 12V, then it should help. But that is not a common part. A more likely part is a 120V input to 9V and 12V output transformer. You could leave the 120V unused and use the two outputs as a 9V to 12V transformer. Actually due to transformer loss, you will get less than 12V this way. So perhaps use a 120V to 9V, 13V. Then you have to figure out how to waterproof your transformer if it sits in the soil.
If you are already exceeding the amp rating of the wires under your driveway, then reducing the bulb wattage is the only safe solution.
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