The ACUPWR Papers

Rush Voltage Explained

We received an email recently from a customer whose ACUPWR voltage transformer didn’t immediately turn on and do its thing. Instead, fuses were blowing in his audiophile-quality CD player. Turns out our customer was dealing with a normal situation called rush voltage (more commonly known as inrush voltage). Here’s how we explained it for him.

Our transformers have a few hundred feet of electric wire that is coiled around a steel magnet inside. When you plug the transformer into the wall outlet for the first time, rush voltage will occur. (It’s entirely normal and something that you should expect will happen.) When the transformer is turned on after being dormant for a significant period—let’s say a week or more—electricity will rush in to fill the transformer’s electric wire. The amount of electricity is large enough that it will trip the circuit breaker and take out any fuse connected to the circuit. We recommend you leave the transformer connected to your appliance, reset the breaker, and power-up the appliance. It might take two or three tries, but once settled in everything will work perfectly.

To explain further, we can compare rush voltage to when a plumber turns off the water line to do his job; The water will drain out from the pipes and through the faucet. When it’s turned on again, lots of air and water rushes out as once. Something equivalent happens with the AC rushing in to fill the coils of the transformer. So, remember that it might take a few resets of the circuit breaker to get your ACUPWR transformer working perfectly.

Also, remember that ACUPWR Is the only voltage transformer that comes with a lifetime warranty. It can also supply twice the stated wattage of the stated transformer for a short period. We do this as a safety measure, but it’s also useful—the extra wattage capability is there if you need it. This is the one reason ACUPWR doesn’t recommend buying double or triple the wattage that your appliances need. Most Chinese manufacturers make that recommendation to ensure that their cheap transformers won't blow up. Why don't they offer a transformer that truly delivers the stated wattage? We honestly don't know, except ACUPWR truly delivers the wattage capability that's stated on the unit. So, if your stand mixer requires 500 watts of power, you can buy a 500-watt ACUPWR transformer. 

Questions? We are always here to help! Contact us at 212-380-1191 or email at You can also chat with us online.

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