Why does the hair dryer switch always have an electric spark?

This is the moment when the switch contacts, and the current consumed by the circuit is large, but the contact area of the switch contact is small or the contact is discharged for a long time to form a carbonization peak with poor contact; If it is fast switching, the area of the switch closing contact is smaller and the switching time is shorter, so the spark is larger.

Your wiring is correct, there is no short circuit, but for the reason I said, it is inevitable that there will be sparks when you strike a fire. The diode on the switch is used to switch the power gear. When the switch is off, the circuit is connected in series with the motor and heating resistance wire on the load to form a loop. Diode half-wave rectifies 220V AC, and the power of blower is halved. But the switch is closed, the diode is short-circuited, the resistance and motor in the whole load are directly connected to the 220V AC circuit, and the blower is fully loaded.

In order to reduce the spark of high current discharge, the common steps from easy to difficult can be used for repair.

1, the simplest way, the current is gradually superimposed. Just don't turn it on at full power at once. If your hair dryer has a hot and cold switch, you can turn off the hot air switch and then turn on the hair dryer, then increase it to half power, wait a few seconds and then increase it to full power, and finally turn it to the hot air switch. If there is no cold or hot gear, you can use the low power gear first and then the high power gear.

2. Check whether the wiring copper wires on both sides of the switch are too thin, or whether the multi-strand copper wires are partially short-circuited or have poor contact. Due to the skin effect of current, multi-strand copper wire is used instead of single thin wire. The solder joint should be smooth, full and firm, and each copper wire should be welded in.

3. Grind the carbonized and blackened contacts and sharp points of the metal contacts inside the switch. If you are a master with strong hands-on ability, you can remove the switch, use tweezers and a small screwdriver to remove the plastic handle of the switch by plastic tension, pay attention to prevent the spring inside from jumping out, slowly cancel the spring and the small steel ball, and then polish the carbonized part and sharp part of the switch contact to make the contact area as smooth as possible.

If you don't want to do it, you have to change the switch. But every once in a while, the ignition of the switch will get worse. You can use my method 1 to reduce the carbonization process. Or you'd better buy a brand-name hair dryer with high cost performance. You can ask the owners of hair salons that they have practical experience in using various brands of hair dryers.