Too many volts at the outlet?


Old 11-17-11, 07:58 PM
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Question Too many volts at the outlet?

Hi, I am a model railroader. I have never had this problem before so I am hoping someone can help. I recently built a very small HO scale train layout for a table top display. Something happened and two of my transformers quit working while being used on this layout. However, I have a 30+ year old transformers that continues to work just fine from the same outlet. Today I purchased a multi meter and I found that the output of the outlet I am using is 123 volts. This seems marinally high for a household outlet. The transformers normally have an input of 115 or 120 volts. Is there something I can do to reduce the output at this outlet so I don't damage any additional transformers? Buying new transformers for a Christmas display is getting expensive... Thanks in advance.
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Old 11-17-11, 08:16 PM
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While 123 volts may seam to be high, but it is within the normal voltage range. Nominal voltage is 120 volts +/- 10%. Transformers are rather robust (especially older ones) and I would doubt very much 3 volts would kill it. The voltage you are reading will vary depending what your reading it with, what load is on the circuit (for fun, check the voltage with out the train running, and then check it again when it is running) and the time of day.
Old 11-17-11, 10:53 PM
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I will be happy to test it once I get my new transformer in the mail. If you would like, I can test the old one as it still works.
Old 11-18-11, 07:35 AM
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Hi again. I have gotten a little information, just in case it helps: The breaker that is used for this curcuit is a 15 AMP breaker; Turning off the power to the entertainment center and time of day did not make a notible change in output at the outlet; I used my old transformer that has for the past 30+ years made a buzzing sound that I don't like and found that the output setting I like for running this train is right around 5.5 volts DC. I also ran the train at 7.8 for a while and that was way too fast for my taste. While running the train, the voltage output did not remain constant, it fluctuated by as much as .5 with no noticible change in speed of the train. I also pulled the plug partically out of the outlet but allowed contact so the train was running and I tested the voltage again while running, also, no real change. It hovered between 122.8 and 123 mostly. Oh, and this may be important, because my wife does not want to see wires, I am not using the AC recepticles for building lighting, so the only draw on the transformer is the DC output.
Old 11-18-11, 10:30 AM
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There is a device called a Variac you can buy at an electronics repair / HAM radio supply type place that allows you to make small adjustments in voltage for hobby electronics. It is true that voltages in the USA used to run a little bit lower (closer to 110V or 115V) so very old components might be a little high on the modern standard of 120V. I do not believe this will be a safety issue with your transformer but since voltage is used for speed control it might run your trains ~5% faster than it was designed for.

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