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Necessary items for using foreign-made electrical appliances in Japan

(Updated June 12, 2022)

You need to be careful not only when taking Japanese electrical appliances with you when you travel abroad, but also when using foreign electrical appliances in Japan. It is dangerous to simply think that "the allowable voltage range for electrical appliances is ±10%, so it is safe.

For example, suppose the following text is written on the plug

  • 50 / 60Hz
  • 110 - 230V
  • 130W

The voltage in Japan is 100V, so it seems out of range, but can it really be used? 230V or higher seems dangerous, but 110V or lower is okay? This is an important question, so let's investigate it thoroughly!

Electricity Around the World

The frequency is 50 Hz or 60 Hz in all countries, and the voltage varies from 100 V as in Japan to 400 V as in Sweden. Incidentally, single-phase and three-phase differ in shape as follows.

Points to keep in mind when using rental equipment


About Hz

First of all, what is Hz? Let me quote from an explanation on the website of Monotaro, the largest industrial e-commerce site.

Frequency is the number of times the electricity flowing in one second changes. Electricity obtained from an electrical outlet repeatedly increases and decreases like a wave. The number of waves in one second (one set of large and small waves) is the power supply frequency. The frequency is expressed in "Hz (hertz).


Currently, there are two different frequencies in Japan: 50Hz and 60Hz, which vary by region. Roughly speaking, eastern Japan is 50Hz and western Japan is 60Hz. Fuji River in Shizuoka Prefecture and Itoigawa in Niigata Prefecture are the boundaries, and some areas have a mixture of both.
Difference between 50Hz and 60Hz frequencies [Mail order Monotaro].


It is interesting to note that even in the same Japan, there are differences between eastern and western Japan. However, it is followed by the following explanation.

The focus here should be on electrical appliances, which are built for 50Hz or 60Hz, and using them at different frequencies can change the speed of the motor and reduce performance, or even cause a fire. In some cases, this can cause damage to the appliance and accelerate its failure. When moving to an area with a different frequency, such as an office relocation, it is important to check which frequency your current appliances operate on.

In recent years, however, an increasing number of electrical appliances can be used with either 50 Hz or 60 Hz. Air conditioners and personal computers can be used regardless of the frequency. In addition, many products are now available with built-in inverters (Hertz-free) that change the frequency of the motor appropriately and adjust the number of revolutions. With recent products, there is little concern about malfunctions. If "50 / 60Hz" is indicated, either frequency can be used.
Difference between 50Hz and 60Hz frequencies [Mail order Monotaro].


In most cases, including this example, new appliances are labeled "50 / 60 Hz," in which case they can be used in both western and eastern Japan.

About V and W

Next, let us discuss V. To begin with, electricity is indicated as follows.

  • Current: ampere (A)
    Magnitude of Electricity Flow
  • Voltage: volts (V)
    The magnitude of the force that causes the current to flow
  • Power: watt (W)
    The magnitude of the work that electricity does

In other words, "current (A) × voltage (V) = power (W).

A typical breaker is 20A, so you can run appliances until the total is 2,000W. As shown below, different appliances have different wattages, and if the total exceeds 2,000W, the breaker will trip.


Basic Knowledge of Electricity - Home Appliance Information Pocket - Panasonic


This example is 130W, so it looks fine. It is a fairly energy-efficient product.

However, the voltage is below the lower limit of this range. People often state that the allowable voltage range for electrical appliances is ±10%, so it is safe, but it is not expected that a current with a 10% difference in voltage will flow constantly. Similar statements can be found on the websites of various electronics manufacturers.

Q. [FAQ0128] Can I use the motor as long as the power supply voltage is ±10% of the motor's rated voltage?

A. It cannot be used. Be sure to use the product at the voltage and frequency indicated on the nameplate. The allowable voltage fluctuation range is ±10% of the rated voltage. This is not a voltage that can be continuously input, but a voltage that does not cause problems in operation if it fluctuates only momentarily.
FAQ0128] Can I use the motor as long as the power supply voltage is ±10% of the motor's rated voltage? | Nissei Corporation

Use within the allowable range of rated voltage. Exceeding the allowable range may accelerate the life of the ballasts and lamps or cause them to fail to light.
Proper Use of Lighting Fixtures


So, for safe and long-lasting use, you must always change the voltage to stay within the specified range. If you use the product without changing the voltage and it breaks, you may not receive a warranty even if the cause is elsewhere.

Of course, simple made products such as light bulbs and speakers are less affected, but the more complex the product's mechanism, the stricter the conditions of use.


In order to transform a transformer, you will need a transformer familiar to international travelers. Transformers are classified into the following three categories

  • Uptransformer ... increase voltage
  • Down transformer ... voltage reduction
  • Up-down transformer...raise & lower

In the above example an up transformer is required. Down transformers are simpler, cheaper and smaller than up transformers.

Down transformer for travel to USA, Canada, Hawaii, Guam, Taiwan and Alaska


This example is 110 - 230V, so either an up transformer or an up-down transformer is required.

Of the manufacturers that produce transformers, the following two are the major Japanese manufacturers.


model number WT - 92J
WT - 3UJ
Input voltage (V) AC100 AC100 (AC110 ~ 130)
Output voltage (V) AC220 ~ 240 AC110 ~ 130 (AC100)
capacity 110W 300W
weight 1.31 kg 1.28 kg
Price* Not for sale 4,800 yen

*Prices on Amazon as of June 12, 2022.


Nissho Kogyo

model number NDF-550UPU
Input voltage (V) AC100 AC100 (AC110 ~ 130)
Output voltage (V) AC110 ~ 130 AC110 ~ 130 (AC100)
capacity 550W 550W
weight 1.7 kg 1.7 kg
Price* 6,999 yen 10,230 yen

*Prices on Amazon as of June 12, 2022.


Since the voltage in every country is either between 110 ~ 130V or 220 ~ 240V, transformers are also divided into two types as described above. Most of the electrical appliances released in recent years are 100 ~ 240V so that the same product can be sold all over the world. However, some slightly minor products are 110 ~ 240V compatible. Therefore, you only need to have one of the two types of transformers.

I also use a Kashimura up/down transformer. (I cover it with plastic, although it doesn't look great, to keep out dust.)



There is no problem with either Kashimura or Nissho Kogyo, but note that the wattage limits are different.

AC110 ~ 130V electrical appliances up to 300W can be used with AC100V (in Japan).

*Do not exceed 80% of rated capacity for continuous use (30 minutes or more).
*Products that generate heat (e.g., irons) and products with built-in motors (e.g., hair dryers) require a rated capacity of at least three times the power consumption.

Transformers/Kashimura Corporation


Note that in this example, if the product is a heat-generating product, it requires 130W × 3x, or 390W. In terms of the products in the table, the NDF-550UPU or SK-550U, which can handle up to 550W, is required. However, these Nissho Kogyo products weigh 1.7 kg, which is almost 1.5 times heavier than WT-3UJ, which supports up to 300 W. If you want to use them easily, WT-3UJ is recommended.

If there is a possibility of using heat-emitting appliances or multiple appliances, we recommend the SK-1100U, which can use up to 1,100W, although the price will be higher.

If you search for uptrans on Amazon, the following product is the first one that comes up, but a cherry checker shows it to be quite dangerous.


Since it is important, use a product from a reputable manufacturer that has a company website and is not considered unsafe by the Cherry Checker.

I hope the above is helpful.

Input output voltage AC110 ~ 130V / AC100V

300W (for easy use)


500W (All-round)


1,100W (If you are likely to use many foreign-made appliances)


See also!