As your railroad grows and you add multiple transformers, it is important to make sure that they are all in phase. All that this means is that the common and hot terminals of the transformers are at the same polarity. For a review of the theory behind this, in addition to what you need to do to phase your transformers, take a look at this video:
Phasing transformers sounds complicated and technical, but it really isn’t that hard. Here’s all you need to do:
- Start with 2 transformers (you can add more later). With the transformers turned off, plug them into a common wall outlet or plug-in strip.
- Attach a wire to the common (black or “U” on most Lionel transformers) of the first transformer. If the terminals aren’t labeled, you’ll simply have to guess. We highly recommend color coding your wires. Since most Lionel transformers use black terminals for the common, black is a good choice.
- Power up the two transformers to the same voltage.
- Test the transformers to ensure they are in phase by using a test light. You can use one of our lighted accessories or a simple grain-of-wheat bulb or LED (make sure it is rated for at least 18 V AC!) Attach one lead of the bulb to the common terminal on Transformer 1 and the hot terminal on Transformer 2. On most Lionel products, the ground is indicated by black and hot by red. If you don’t know, you’ll just have to guess. If the light turns on, you’re in phase. If you don’t get a light, you’ve connected common-common or hot-hot.
- Now that you know which poles are the same and opposite, connect the two ground terminals with a black wire. (We recommend black due to the normal color code on our transformers.)
- Double check with a light from Transformer 1 Ground to Transformer 2 Hot.
- If you have additional power supplies to add, repeat this process by connecting another wire from the Transformer 2 common to number 3 and so on.
Ensuring your transformers are in phase takes only a minute and will be critical as you wire accessories, common-rail wire multiple track loops, and add additional power supplies going forward.