Why disable high-power appliances?
This is related to the age when the school dormitory was established. Most university dormitories have been used for nearly ten years or decades, and the service life of the wires in the building is not short.
10 years ago, the quality and standards of electrical materials products were far worse than now. It has fallen into disrepair. Although the distribution box and other equipment have been replaced in recent years, the wires embedded in the wall are rarely replaced. At that time, there were far fewer high-power appliances than now, so the large-scale use of high-power appliances was not considered in the selection of dormitory wires, and most of them chose to use 2.5 square meters of wires. Coupled with years of disrepair, the current carrying capacity of wires in the dormitory will be much smaller.
If large-scale use of high-power sockets will lead to the following results:
Overload. According to common sense, 2.5 square meters of wires can be used for rapid heating, induction cookers and other electrical appliances. However, if each dormitory uses heat quickly, or a dormitory uses multiple high-power appliances at the same time, the main current will be too large.
It's on fire. One of the consequences of wire overload. Everyone should know that the consequences of a fire in a dormitory are very serious. In addition, as we said above, if the wire is overloaded, it is easy to catch fire because of poor quality, poor conductivity and thin wire.
Economic account. This should be the main reason why high-power electrical appliances are still not allowed in school dormitories in this era of technological development. How much does it cost to replace the wire? How much is the electricity bill? Dormitory fees are fixed. No matter how much electricity you use, it's so much money. Why should I let you use it?
Now the newly-built student dormitories are all equipped with high-quality thick wires, and generally each dormitory has an independent electricity meter, so students can buy their own electricity. Such schools generally allow the use of high-power electrical appliances in the dormitory, anyway, it is their own consumption!
The way the school controls students to use high-power electrical appliances is that each circuit breaker controls a dormitory. The choice of circuit breakers is generally small, such as normal household circuit breakers at least 20A, while schools often choose 10A or even smaller circuit breakers. In this way, when there are high-power appliances in the dormitory, it will cause tripping.
Why is the terminal board disabled?
Disabling the wiring board really has nothing to do with the school trying to save money! Moreover, the wiring board can't be controlled uniformly like high-power electrical appliances, which makes it difficult for schools to check, which is the most headache for schools.
It is forbidden to use the terminal board, mainly for safety, including the branch current and trunk current I just mentioned. The specific reasons are as follows:
Overload. It's still the problem of main current and sub-current just mentioned, but the environment has changed at this time. Each dormitory is generally equipped with 4-8 five-hole wall sockets, and each five-hole socket can only use 1 electrical appliances. Let's assume that the current of this appliance is 2A in normal use.
Generally speaking, the rated current of a five-hole socket is 10A, so 2A electrical appliance can definitely work normally when using this socket. But if you use a terminal board, assuming there are 6 jacks on the terminal board, you can use 6 such 2A appliances on the terminal board.
At this time, the five-hole socket is on the trunk of the wiring board. In the pure resistance circuit, the main current is the sum of the currents of each branch, and the non-pure resistance circuit will change, but it is almost the same. If the six holes of the terminal board are used at the same time, the current at the socket is about 12A, which is far greater than the rated current of the socket, but the circuit breaker at the distribution box does not trip, which can not play a protective role (the current can not reach the value of the circuit breaker action).
In this way, the socket is overloaded, and the socket is overloaded for a long time, which will cause a fire.