04:20AM | 09/12/08
Member Since: 03/04/03
44 lifetime posts

I'm using a Magnitude M200S transformers for a residential application (my kitchen) running 6 WAC HR-86 Under Cabinet Button Lights. Each light is spaced about 2 feet apart from one another. The transformer is 110/120v in, 12v 200watt out. The lights are 12v/20 watt each.

The 1st light in the run is about 15 wire feet from the transformer. The last light is about 30 wire feet from the transformer. Although the lights are within 2 feet proximity to one another, two of them have about 15 wire feet between them as I had to run a loop around some cabinets.

I just got done making final connections and when switched on the lights are very dim. Each is less bright than a birthday candle, as a comparison.

I used 12 gauge copper stranded wire from the transformer to the lights. The supply wire (a/c side) to the transformer is 12/2 bx.

I would imagine I have one of two problems as to why the lights are dim. Too much resistance (a voltage problem) or too little watts (a transformer capacity issue).

Some thoughts I have are run two transformers in series to boost voltage output. Replace the transformer with a larger capacity (300watts) transformer. Or replace the transformer with a 24v version.

I don't think it is a capacity (watts) problem. I suspect the length of the feed and return wires is too long and creating too much resistance.

Does anyone have any experience with this or pointers on next steps?

Thank you,



11:12AM | 09/12/08
Member Since: 09/17/02
524 lifetime posts
Please tell us how you connected the lights. It sounds like they are all in series instead of parallel.

If you remove one bulb does all the others go out?


11:23AM | 09/12/08
Member Since: 03/04/03
44 lifetime posts
I reviewed this with the retail outlet that sold me all the parts, and they feel it is resistance when the wire steps down from the 12 gauge stranded supply line to the 18 gauge leads hanging off the lamps. They recommend I remove the 18 gauge leads from the lamps and just go 12 gauge direct to the lamps, and the problem will be corrected.

This just does not sound right to me.

The lights are wired in series, and I realize what probably is happening here is I effectively reduced the 12v supply from the transformer, to 2 volts to each (of the six) lights. I bypass one light, the other five will brighten.

Unfortunately, now that all the cabinets and back splash is in place, home running each light to the transformer is difficult.

Is it feasible to wire three 24 volt 40 watt (minimum) transformers in a series to create 72 volts at the line. That should enable the lights to operate at the correct luminosity (six lights at 12 volts each = 72 volts). I am not certain, however, if this is possible, or safe.



03:39PM | 09/12/08
Member Since: 07/22/04
661 lifetime posts
you need to redo the wiring and put the lamps in parallel with each other.

you also need to break it down into two circuits and add another transformer because the total you have now is going to stress one transformer and cause it to get too hot and fail sooner than it should in my opinion.


03:45PM | 09/12/08
Member Since: 07/22/04
661 lifetime posts
only need one transformer,one circuit.

plenty of reserve.

bulbs need to be in parallel.


08:41AM | 09/13/08
Member Since: 03/04/03
44 lifetime posts
Change to parallel and everything works fine now.

Next time I ignore the retail guy selling me the parts and trust my judgment.
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