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Electric fuse boxes a.k.a circuit breakers a.k.a 漏电断漏器 [lou4dian4duan4lu4qi4] come with the home. Knowing a bit about them will help you during the house hunt as well as after you settle in.

I’m no electrician. What I’m sharing I learned from the guy who fixes my apartment. Above is an open fuse box. It doesn’t just look old, it’s part of an older apartment, and we’ll soon find out why. Just to make things clearer, we will divide this fuse box into the main part and the 3 slots on the right. The main part is made of left (two red square lights), middle (switch) and right (button).

The switch you see in the middle is for you to connect to or disconnect the main lines (from outside the house) from the lines in the house. 220 Volts run through the main lines, through the circuit breaker, to connect to the lines in the house.

Now, on the right side of this picture, you see three vertical slots, two of which are filled - the one in the middle shows signs of a burning past, and is empty. These slots connect the lines in the house to the main lines outside the house.

What happens in a normal situation is this: the main line splits into three lines. Because the main line carries 220V, each of these three lines will also carry 220V. Because each line has about 16 to 20A (amperes) of current running through, the wattage per line (meaning the amount of power per line) can be calculated. It is calculated like this:

Power (W) = Current (A) * Voltage (V)

That’s about 3520 to 4400W per line.In many cases, one line is used specifically for the airconditioner 空调 [kong1tiao2]; one line is used for the electrical sockets [cha1zuo4]; one line is used for the lights 照明 [zhao4ming2]. If you put a fuse into the slot, you connect the lines in the house to the circuit breaker to the main lines outside of the house.The fuse for a particular line burns up if the electricity in that line exceeds what it can handle. When the fuse in a particular line is burned, the line is disabled from use. So, to be able to use the line again, you need to put in a new fuse.

In the case of this circuit breaker, only two of the lines are used. The two filled slots have fuses in them. One of the slots represents the line that connects to the electrical sockets in the house - and that includes the sockets for the aircon 空调 [kong1tiao2] too. The other line is for the lights.

Now, let’s think about the line that goes to the electrical sockets in the house. Let’s estimate 2500W for a heater/air-conditioner a.k.a 空调 [kong1tiao2]. An electric kettle will use up about 1800W. What about the electric water heater when you need to heat up hot water for a shower - that’s 1500W. And maybe another mobile heater for 1800W? Are we gonna overuse those electric lines in winter? Probably.

That’s why that middle slot is not vacant and slightly charred. It once was used to contain the fuse that connected to the ‘electric socket’ line. Does this house cut it? You decide.

So, remember to ask your future landlord how much power is in the lines. Better yet, ask him what each of the lines is connected to.

Qualifier: I’ve written only what I understand as a layman. Anyone more knowledgeable, please feel free to contribute more information or correct me. Thanks.