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2 low voltage transformers on 1 circuit?

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2 low voltage transformers on 1 circuit? dchou4u@hotmail.com 05-03-2008
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Posted by RBM on May 3, 2008, 9:59 am

>
>
> >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
>
> 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

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..





Posted by Tony Hwang on May 3, 2008, 10:18 am
hallerb@aol.com wrote:
>
>>
>>
>>
>>>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
>>
>>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
>
>
> 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..
>
>
>
Hmmm,
I got rid of all that. Switched to solar power.

Posted by CJT on May 3, 2008, 5:32 pm
hallerb@aol.com wrote:

>
>>
>>
>>
>>>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
>>
>>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
>
>
> sorry your confusing wattage of 2 different voltage ratings.
>
> 20 amps at 120 volts is 2500 watts.........
>
> but ratings change at 12 volts........

20 amps is/are still 20 amps

>
> 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..
>
>
>


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

Posted by Art Todesco on May 3, 2008, 10:40 am
RBM wrote:
>> 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
>
> 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
As the OP came from googlegroups (which
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.

Posted by peter on May 3, 2008, 12:27 pm
>>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.

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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