Security & Fire Protection Systems/Napco Transformer replacements


QUESTION: Read your interaction on web.  What is best replacement for Napco Alarm Transformer TRF12 - T123 at 120AC, 60Hz, 24w, 16VA, 1.2 amps?  Suggestions.  Replaced 7amp battery, electric switch works, some output on old transformer, but minimal.  Black burn dust on plug plate.  Triangle in bottom left corner of alarm panel red.  Replacement suggestions?  Looks like Napco is no more.  Only ebay sales.

ANSWER: Hello Dale, and thanks for writing.

For transformers for alarm panels, it's not important to match brand name, but it is for the transformer specifications. There are two specs that you need to match: primary and secondary voltage, and VA.

In your message, I didn't see a secondary voltage listed (that's the output, and it's likely 12, 16.5, or 24 volts AC or "VAC"), so just look at the old transformer, get the secondary voltage, and Google that (i.e., 16.5 v 16 va transformer). You'll get a lot of hits, so you can shop by price.

By the way, you can higher than the VA listing on your transformer, but not lower. So if you replaced the 16 VA transformer with a 40 VA, the alarm will be fine, and the transformer will run cooler. Hot transformers cause that blackening "burn dust."

I hope that helps!

Best Regards,


---------- FOLLOW-UP ----------

QUESTION: Thanks Dave.  The transformer has a 16VAC I believe.  So is that the secondary?  The primary is what?  It said, 120AC, 60Hz, 24volts, 16VAC, and 1.2 amps.  What are the two you are referring to?  I would assume you mean the 120ac and the 16VAC.  Dale

Sorry for the confusion ... watts and VA are the same thing; on transformers the usual designation is listed as VA.

But I check one of my old manuals for a NAPCO panel and found that the TFR12 is equivalent to the Basler 16.5, 20 VA transformer.

Like I said, brand isn't important, so something like this will be fine:

Best Regards,


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Dave Neuweiler


The design and application of burglary and fire systems for homes and businesses. Helping alarm owners understand how their system works. Helping to troubleshoot false alarm problems. Questions about monitoring issues.


Over a quarter century in the industry. Experience in installation, service, and monitoring centers. Training manager for a national protective services company; director of education and training for a national trade organization for for alarm dealers.


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