Electricity contracts for homes in Japan are based on a concept of contracted capacity measured in amperes (A). Using too many appliances at once can trip the breaker and cut the power, which is a point that often catches first-time residents of Japan off guard. Here, we'll go over how amperage and breakers work, and the procedure for changing your capacity. Knowing how the system works makes it easier to stay calm if the power suddenly goes out.
- Contracted amperage refers to the contract term that sets the upper limit on how much electricity you can use at once.
- Using appliances beyond your contracted capacity trips the breaker and cuts power to the entire room.
- In many cases you can change your contracted amperage by contacting the electric utility, but there's also an upper limit set by the building itself.
- Care is needed when using high-wattage appliances such as air conditioners, microwaves, and hair dryers at the same time.
- The amperage set when you move in is often determined by the property, and you can check it on your lease or your meter reading notice.
What Is Amperage?
Amperage (A) is a unit of electrical current, and in many Japanese homes, electricity is contracted by setting a "contracted amperage" with the utility company. The higher your contracted amperage, the more electricity you can use at once, but the base rate tends to rise accordingly. A typical single-occupant room might be set at around 20-30A, while a family-oriented room might have 40A or more. Contracted amperage is part of your contract with the electric utility, and some properties have an upper limit set in advance.
How Breakers Trip, and What to Do About It
If you use more electricity at once than your contracted amperage allows, the breaker (the amperage breaker) automatically trips as a safety measure, cutting power to the entire room. If this happens, turn off some of the appliances currently in use, then flip the breaker switch on the distribution panel back on to restore power. The distribution panel is often located near the entrance or the washroom, so it's reassuring to locate it when you move in. The moment the power goes out can be startling, but checking the distribution panel calmly usually gets things back on quickly.
How to Check Your Contracted Amperage, and the Procedure for Changing It
Your current contracted amperage is often noted on your meter reading notice (denki shiyōryō no oshirase) or the distribution panel, and you can also confirm it by contacting your electric utility. If you want to raise your amperage, you can make the request by contacting the utility, but since the building's equipment may set a limit on how far it can be changed, it's worth checking with the management company as well. How long the process takes varies depending on the utility and whether construction work is needed. Many utilities let you complete the process entirely online or by phone, and being present in person isn't always required.
Watching Out for Overloading When Using Multiple Appliances at Once
Using high-wattage appliances at the same time — an air conditioner, microwave, hair dryer, and electric kettle, for example — makes it easy to exceed your contracted amperage. This calls for particular care in summer or winter, when you might run other appliances while the air conditioner is on. If your breaker trips frequently, it's worth considering raising your contracted amperage. Just being thoughtful about which appliances you run together can reduce how often the breaker trips. If you have an especially high-wattage appliance, such as an IH cooktop, it's reassuring to consider setting your amperage with some margin to spare from the start.
Changing Your Amperage When You Move
When you set up your electricity for a new home, you can often check and change your contracted amperage at the same time. We cover the overall procedure for setting up utilities in more detail in a separate article, so please check that as well. Getting in touch with the electric utility before you move in lets you use electricity with peace of mind from day one. In some cases, you can simply carry over the previous tenant's contracted amperage, so if that matters to you, it's worth confirming in advance.
Frequently Asked Questions
What should I do if the breaker trips?
Turn off some of the appliances currently in use, then flip the breaker switch on the distribution panel back on to restore power.
Can I change my contracted amperage any time?
In most cases, you can change it by contacting the electric utility, but since the building's equipment may set an upper limit, it's reassuring to check with the management company as well.
What should I do if the breaker trips frequently?
Besides using fewer appliances at once, you can also consult the electric utility about raising your contracted amperage.
Summary
Understanding how amperage and breakers work lets you stay calm even if the power suddenly goes out. If your breaker trips frequently, try reconsidering how you use your appliances, or consult the electric utility about changing your contracted amperage. Even a small adjustment to your daily appliance habits can go a long way toward using electricity comfortably.