Low voltage lighting transformer

[Richard]

Couple years ago, we bought some low voltage lights and a transfomer. Wife loved the look, wanted more lights, so she bought a second transformer and another set of lights.

Last year, our dog chewed up a couple of the lights, so wifey found & bought a couple replacements.

now she wants to reconfigure their layout. To that end, she bought a 100' power cord and 4 additional lights.

Given her layout, the most efficient path, is a single path for the wire, rather than splitting the two.

This means, I got to double up the lights onto one circut. I realize I cant have the wattage of lights exceed the transformers output... bad part is, the transformer not only doesnt' give me that infomation, it has NOTHING on it at all....brand, model, nothing.

Any way that I can test the output to ascertain it's output semi-accurately so I dont blow myself up? /forums/images/graemlins/crazy.gif

Or should I just bite the bullet, throw BOTH of them away and go buy a new transformer with "known" specs that will fit my needs?

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[BB_TX]

I am guessing the transformer is actually inside a plastic housing. If you can open it, the transformer might have some numbers on it to tell the wattage.
Also, keep in mind that the lights at the end of that 100' wire are probably not going to be as bright as the ones closer to the transformer. That will create some uneven lighting which may or may not be a problem.
I also have a fairly long wire. But I connected the wire from the transformer to near the center of the long wire. That minimizes the voltage drop to the end lights.

 

[Richard]

gotta admit, never thought of opening it up!

I just hung up with a domestic manufacturer of them, he said on a 100' run, to have no more than 100 watts of draw. As I emotionally prepared to purchase a second transformer, he said...nope...no need for that either... that you can just hook the second set of wires to the transformer. Sort of like the transformer being the octapus head and the wires being the tenticles, or, like YOU did, by hooking it up "in the middle" which served the same effect.

I'll take it/them apart tonight. I have two of them and prefer to scale back down to one. With the advent of 100' = 100 watts, I might still need both of them though /forums/images/graemlins/frown.gif

 

[Richard]

as per his comment of putting another set of wires on, we were discussing using a 500 watt transformer which has the net capacity of my needs met plus some headroom for expansion (if ever).

I didn't want it to infer that I was willy-nilly adding runs to a (potentially) underpowered transformer.

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[TWINKLE_TOES]

Richard, if the two transformers are identical you can operate them in parallel with a current capability of twice that of an individual transformer. The transformers must be phased properly or they are mutually shorted. To determine the proper phasing measure the secondary voltage of one of the transformers. Now connect the secondaries in series and measure the secondary voltage. It has two possibilities near Zero or twice that of an individual transformer.If it near zero connect these two lines togather and use the junction of the two transformers as the return line. If the voltage is not near Zero reverse one of the transformers and proceed as above.

 

[reb]

I would use both transformers, each with 1/2 of the lights. Just run both sets of wire in the same trench. There are ways to test them with the full load, but could be risky to those not electrically inclined.

 

[RobertN]

Check out www.uniquelighting.com/

They have awesome, albeit $$ stuff. Thier transformer give multiple power taps of various voltage, so you can put the proper voltage to lights, whether it is on a short run of 25', or a longer run of 100'. They also have many lights which have metal housings, for doggy proofing.

You can "T" off in equal lengths to try to balance the light/current load. You could also run a lower voltage tap to closer lights, and a higher voltage tap to lights further away. The further away the light is, the higher inital voltage you need to overcome the IR(voltage) drop in the wire.

Low voltage wire is relatively cheap; run the extra wire to do it proper the first time.

 

[Richard]

Welp, I took one of them apart & presume they have same output, as they "look" identical, and I mean identical.

anyway, seems output as per transformer inside is 150 watts max.

I kinda liked the idea of going down to a single transformer however, with the 100watts/100' theory I was told, I guess it's just as well that I keep them both and use a shorter feed wire (or what ever you call the wire on ground!)

Thanks
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[_RaT_]

Depending on the ligth fixture used, voltage drop will be a minimal or major concern. I've put in many low voltage lighting systems indoors. In some cases we will have over 50 transformers in a home serving various lighting loads, most of which are all halogen MR 16 lights. With each 50 watt MR16 bulb drawing a little over 4 amps (50 watts/12V), you can see that a long wire run will severely drop the voltage on outdoor lighting. Tapping the 13V or 14V is not a solution either since the first fixture will receive much a substantially higher voltage, something halogen does not tolerate well. Solution, run large wire. For outdoor use, we always start with #10 and go from there. We always use at least 3/4" PVC conduit. We typicaly use 300 or 500 watt transformers made by ACME because they are relatively inexpensive and all stainless steel. Our fixtures usually come a friend of mine that owns BK lighting down in Fresno California. They have some incredible stuff. BK Lighting Outdoor lighting can really add a lot.

 

[RobertN]

Yup, the only way to tap and run the higher voltage to the longer run is to have more than one run, based on distance and IR drop. The bigger transformer are nice for inital installation, because you can usually add on later; plan for some expansion possibilities.

Big wire is a good idea, and wire is usaully comparitively cheap compared to the rest of the bill.