Track Lighting

Welcome to a2k, rchrusciel.

We have a couple of experts on such things here - I'm sure one of them will come along and provide some help.

The transformer is shutting down because it's being overloaded.

Do you have all the same bulbs in both units? (they should each have five 20 watt 12 volt MR16 halogen bulbs.)

If you take out one bulb from the fixture that is overloading does the transformer still shut down?

Are your wiring connections secure? Any even slight poor connection will effect operation. How far away is the track from the transformers and, as fisin' points out, how close are you to the load of the transformer? Typically because of inherent voltage drop even with the best connections, you should only put a load on the transformer no more than 80% of the rated watts. So if it is a 100 watt transformer, you should only load it up to 80 watts.
Also, is it a magnetic or electronic transformer? Electronics don't fare well when connected more than six feet from the end of the track or other fixture.

BTW, a dimmer will unlikely do anything to alleviate the problem and it must be electronic if your transformer is electronic. These off-the-shelf lighting kits are often problematic because of the gauge of the wiring.

This seems to be pretty common-sense to me too but I noticed that these are sold through Home Depot and they are listed as coming with a 105 Watt transformer and with five 20-watt bulbs for a 100 watt load. Seems to be pushing the edge but...

Home Despot -- yes, the premier perveyor of lighting fixtures (and other items) made to their quality specifications. It's could be the terrible lamps they provide which often draw more than their rated amps. The first thing to do if they are MR 11's or 16's from China or Indonesia is throw out the lamps (they're unlikely to last more than a few months anyway) and replace them with decent lamps. You are correct that this is likely overloading the transformer because of too long a connection between the transformer and the track (unless the transfomer is at the end of the track and the 120V wiring is run up to the transformer). This isn't one of the tape, wire or rod systems is it? Those will frequently thwart the user in making poor connections or putting all the fixtures towards the end of the track which will also overload the transfomer's output protection.

All Halogen lamps, BTW, are not the same. I only provide USHIO which are made in Belgium to strict specifications and quality control. Not so the imports coming from Asia, except for Japan, Taiwan and Korea (even then, you can't be sure of the particular factory). USHIO also makes all the technical lamps and the projection equipment for movie theaters. 20 Watt MR 16's are not going to deliver the bright white light of the higher wattage Halogen's to begin with. A dimmer will also deteriorate the color temperature.

The ficture is the double metal rod type, with the transformer in the middle of the rods. From what I can tell, the transformer is magnetic. I have triple and quadruple checked my connections to the transformer, but I can see where the two screws connecting the rods would cause some problems. All of the lampss in the unit are the same make as they came with the kit. As this is my first halogen setup like this, I have to ask, do they sell a 15 watt bulb, so I could bring the load down?

No, they make 10 watt but they aren't readily available and are mainly for outdoor landscape lighting. I think this sounds like a design flaw -- the first connection to check is the one to the transformer (and I am sure it is magnetic as it would be more likely with a rod system). They are really loading the system to its max and should be recalled. You could also have one of the fixtures not securely connected to the track. Any small gap or loose connection will cause a problem. The big problem is they should be shot for selling a product like this.

BTW, although a 100 watt load is only a small amount of amperage, if the products safety were to fail, this product could cause a fire.

Peronally, I'd return the product and tell them to bend over so you can place it where the sun don't shine.