[Reading Science] Do Power Strips Also Have Allowed Capacity?

Power strips have a specified allowable capacity (limit capacity). They should be used at about 80% of the allowable capacity.
[Photo by YouTube screen capture]

[Asia Economy Reporter Kim Jong-hwa] To use electricity, you need an outlet. Electrical devices operate only when their plugs are inserted into outlets that supply electricity. However, when there are too many electrical devices in use, causing a shortage of outlets in the home, or when the distance between the outlet and the device is far, what is used is a 'multi-tap' (power strip).

Did you know that even multi-taps have a 'rated capacity (allowable capacity)'? Commercial multi-taps used in typical households usually have 2 to 5 sockets, while industrial ones used in venues like concert halls or stadiums can have more than 10 sockets. Is it safe to plug in devices into all these sockets without any issues?

Multi-taps also have a limit to the capacity they can handle. According to the Electrical Appliances Safety Control Act, multi-taps have their rated voltage indicated. On the back of the 5-socket multi-tap I use, it says 'Rated 16A 250V.' What does this mean?

The allowable capacity (W, watts) of a multi-tap is calculated as 'Voltage (V, volts) × Current (A, amperes).' So, for the multi-tap I use, it is calculated as '250 × 16 = 4000.' This means the multi-tap allows a usage of up to 4000W.

Even among 5-socket multi-taps, some products are labeled 'Rated 10A 250V.' This is because the overload capacity varies by product. The allowable capacity for this product is '250 × 10 = 2500.' This is much less than the 4000W capacity of the multi-tap I use.

Back of the power strip. Rated '16A 250V' is indicated. Photo by Kim Jonghwa

The appropriate usage of a multi-tap is within 80% of its allowable capacity. For the multi-tap I use, 80% of 4000W is 3200W, which is the proper usage amount. For another 5-socket multi-tap with a 2500W allowable capacity, the appropriate usage is 2000W. Exceeding this can cause sudden power consumption spikes that may lead to fires.

So, how much power do individual electrical devices consume? A refrigerator, which occupies one outlet socket constantly, consumes about 1500W per hour.

Depending on the manufacturer, there are differences, but generally, air conditioners consume about 3000W per hour, drum washing machines 2200W, microwave ovens 1600W, electric rice cookers 1000W, vacuum cleaners 1100W, home heaters 2200W, irons 1500W, and computers 230W.

On the multi-tap at my desk with a 4000W capacity, my computer and monitor are always plugged in, consuming about 350W per hour. You should not plug an air conditioner into this multi-tap because adding the air conditioner's 3000W would exceed the appropriate capacity of 3200W. Adding a home heater and a smartphone charger would be acceptable.

Using a refrigerator, air conditioner, and drum washing machine together at home is very dangerous. High-power devices like air conditioners, drum washing machines, and home heaters should ideally be used alone without a multi-tap. Especially for air conditioners, it is recommended to use a dedicated multi-tap or plug them directly into the outlet.

Also, using 2 to 3 electrical devices simultaneously on the same multi-tap is risky. It is common to plug a drum washing machine (2200W) and vacuum cleaner (1100W) into the same multi-tap. Adding an electric rice cooker would total 4300W, which is enough to create conditions for a fire.

Of course, multi-taps with 4 or more sockets have minimal safety devices to prevent overload. Some products automatically cut off power when overloaded. However, knowing that multi-taps have a rated capacity, you would not fully load them, right?

When purchasing a multi-tap, checking the rated capacity and separately noting the power consumption of electrical devices to allocate the power usage and arrange the positions of multi-taps and devices accordingly is a wise approach to daily life.