Breaker, breaker: How to conserve energy without thinking too much

July 4th, 2012 by Philip Brasor & Masako Tsubuku

Power trip: electrical panel with 30-ampere main breaker switch

Last Monday the summer setsuden (electricity-saving) campaign started. All the regional utilities except Okinawa’s are requesting that customers cut back on their energy use so as not to put a strain on the grid, which has been compromised by the shutdown of so many nuclear power plants in the wake of last year’s meltdown at the Fukushima No. 1 reactors. As evidenced by the large anti-nuclear demonstrations taking place, a lot of people have strong feelings about atomic energy, but whether you believe it to be too dangerous to handle or an acceptable alternative to carbon-based sources, the best way to address the more pressing issue of energy shortages is to reduce usage.

Though there are many piecemeal methods for saving energy, one way to immediately cut down is to exchange your main circuit breaker, the gatekeeper for the current that flows into your home. Power is measured by means of watts, and the number printed on your breaker, which stands for amperes, represents the maximum amount of wattage that can pass into your home at one time. Different household appliances use different amounts of power. Anything that cooks or produces heat will use more power than other appliances. When the amount of power flowing into your home exceeds the ampere level of your breaker, it automatically trips, causing a blackout, but only in your home. If you use a lot of electricity, then you should install a breaker with a higher ampere number.

In Japan, household breakers come in seven steps, from 10 amperes to 60. The higher the number, the higher the basic charge on your monthly electricity bill. If you are a Tokyo Electric Power Co. customer you pay ¥273 for 10 amperes, ¥409 for 15, ¥546 for 20, ¥819 for 30, ¥1,092 for 40, ¥1,365 for 50 and ¥1,638 for 60. In order to figure out which breaker level is appropriate, take a survey of all your household appliances and how often you use each one.

There is an indication on the appliance and in the accompanying user manual of how many watts the device uses at a given time, though some experts say these tend to be inflated. If you want to know exactly, then buy a wattage monitor for anywhere between ¥2,000 and ¥20,000 at an electrical appliance store. You plug your appliance into it and it will tell you how many watts the device uses. Then, if you use the simple calculation of 100 watts per ampere, you can estimate which breaker level is best. A refrigerator, for instance, is on all the time and the average one requires 2 amperes on a continuing basis. A microwave or a rice cooker may require as much as 6 amperes, but they tend to only be used for short periods of time. An air conditioner starts off using a lot of power but eventually levels off to much less.

Utility companies will say you should add up all the amperes required by all your appliances to find out what level you need, but that is hardly a way to figure how to save because you aren’t going to use all your electrical devices at one time — or, at least, you shouldn’t. To make managing your appliances easier use switchable power strips — extension outlets with switches that cut the current to individual appliances.

According to Asahi Shimbun, there was a 50 percent increase last summer in the number of Tepco customers who requested replacement breakers, and though the report doesn’t specify how many increased their amperes and how many decreased theirs, we can probably assume the majority were in the latter category; given the setsuden push last year. One family profiled by Asahi stepped down from 40 amperes to 20, after which they experienced two blackouts because they used the toaster and the microwave oven at the same time. Now they have no problems because they understand how to balance their power usage. More importantly, they say they don’t feel inconvenienced at all.

What’s notable about this trend is that it was promoted by users, not utilities. When utilities talk about changing breakers, they frame it in terms of household economy — you can save money — not in terms of energy-saving. This seems odd since changing to a smaller breaker is a good way of compelling a household to pay closer attention to the amount of energy it uses. By the same token, having a larger breaker than what a household normally uses could lead to a waste of energy. If promoted on a mass scale, changing to smaller breakers could theoretically prevent the sort of regional blackouts the power companies say are likely to happen during peak usage periods this summer. If all households exchanged their breakers for smaller ones, then the grid would seem to be in less danger of momentary overload because those breakers will trip at lower usage levels. The point is that the resulting outage will only affect the individual household, not the grid. In this way, overall usage is checked.

But maybe that would be too much savings for the power companies. After all, they are profit-making organizations. Last week we called Tepco and asked to have our 40-ampere breaker exchanged for a 30-ampere one. Originally, we were thinking of alternating between a 20-ampere breaker for the summer and a 30-ampere breaker for the winter, since much of our heating is electric, but Tepco says you can only change your breaker once a year since that is the minimum period for a billing contract, so we settled for the 30-ampere. When we talked to the Tepco representative on the phone, she made a point of telling us that 30 might be too small. “You can’t use two air conditioners at the same time,” she warned. “We don’t have any air conditioners,” we said. She stopped talking.

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7 Responses

  1. We have a different kind of breaker since installing solar panels (installed with the panels) but no complaints since our pay back each month is over 2x what we pay :)
    The electricity monitor which u recommend & also came with the solar system is a real eye opener on usage at home, so I reckon just getting that alone might help balance use. We were most surprised by lights, 1 click dimmer means big savings, also with A/C one degree warmer is a huge consumption change over an hour/day

  2. I love reading your blog but I think you have not quite grasped that circuit breakers do not have a great affect on energy saving. It only stops overload. Base load energy usage is what is important – of which a circuit breaker does not have much of an affect.

  3. Thanks for the clarification. We understand that changing the breaker will not in and of itself reduce energy consumption. The point being made in the Asahi article was that changing a breaker made a household more aware of the electricity it was using, since it had to be more careful to avoid overloads. Once you understand how much energy each appliance uses you have a better idea of how to cut down. That said, we also understand that reducing energy consumption by individual households has no effect on the amount being produced. It can only have an effect on how much of that energy is consumed, so if households use less there is less danger of an overload.

  4. Re excess energy it is not so simple a situation. Gas turbines can be turned on and off at a switch of a button. Coal power can be tuned every 15min. Nuclear is set. But excess energy can be converted to hydro power. Also factories can use night shifts for high power work. So turning off a light can cause a difference.

    Also regarding overload there can be a little more to it as well. Faulty appliance or appliances with a high starting load can cause a suddon peak that will trip your breaker. Although you are correct in adding the wattages it is not always that simple. I have personally experienced this.

    Anyway I understand your premise but I think it may be an over simplification.

    Love reading your blog (and the other one regarding housing). Not trying to be negative!

  5. Hello:

    Long time reader, first time responder. I am an electrical engineer and can shed some light on how the breaker system works. The 10-20-30-40-50-60 Amp breakers refer to the TOTAL electrical service provided by the utility. There are secondary breakers set at lower levels (20Amps in your picture) that control INDIVIDUAL circuits in the dwelling. These tend to be for individual rooms: bedrooms, bathrooms, or specific appliances: ovens, dryers. In Canada, where I am from, the standard service is 100 Amp, 200 is optional but requires re-wiring to the house.

    As Alex pointed out, changing your service to limit your peak load isn’t beneficial. All it will do is stop you from running the two appliances at the same time. You can accomplish the same affect by running them on the same individual circuit rather than changing the full breaker.

    As you mention, consumption awareness is a much better tool at reducing overall usage.

    I am more surprized that there are so many choices in the breaker/service levels available to the user. Trying to save 500Yen/month by changing you breaker because there is a surplus of capacity illustrates more that the billing system is broken rather that there is something wrong with the breaker.

  6. Sorry to keep commenting on your entry but I have been pondering why TEPCO would charge you more for a bigger breaker. I assume you have a meter. How does your meter work? Does it store data and are you charged different rates at different times?

    I wonder if they charge you more for the bigger breaker for other reasons. It is a little interesting to me and I think TEPCO would not do it without good reason.

    Would the breaker charge exist if you had a house?

    Also in your article you mention a max 60A breaker per home? Is this true? This seems far too low for a large house. I would expect it to be more like 80A to 300A for a new house.

    I think I am showing my nerdy side.

  7. Tepco isn’t “charging” for larger capacity breakers. They simply peg the “basic fee” (基本料金, “kihon ryokin” on the monthly bill) to the size of the main breaker. You pay that fee every month even if you use no electricity at all. As far as we know, as long as you buy your electricity from Tepco (as opposed to generating some of it yourself, as another reader does) you have to use this system, regardless of whether you own or rent, live in a house or an apartment.

    60A may be too small for some North American houses, but it seems to be plenty for most Japanese houses. Businesses tend to use much more electricity, so we assume homeowners can also opt for larger breakers and can make arrangements with Tepco, but from what we were told on the phone 60A is the norm.

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