Several ways to control a double switch of a lamp - Solutions

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In daily work and life, it is often the case that you need to control the opening or closing of a light, an AC contactor or other electrical appliances in two places. It can be achieved by wiring two double-connected switches as shown in Figure 7. For example, a double switch is installed at the door of the bedroom and at the edge of the bed to control the bedroom ceiling lamp. In this way, when the door is opened at night, the switch on the side of the door is opened, and when the door is put into the bed, the switch on the side of the door is opened, and when the bed is put up, the switch installed at the bedside can be turned off.

There must be two control lines using the wiring method shown in Figure 7. This is difficult in some occasions, such as the original threading pipe is relatively thin, and the wire is trapped.

difficult. At this point, the wiring method shown in Figure 7 can be changed to the method shown in Figure 8, in which case only one control line is required. This is what the old electrician often calls "double fire" circuit. The biggest disadvantage of this wiring method is that when the light is not lit, it is possible that the switch is connected to the phase line, that is, both ends of the light may be connected to the phase line. If the maintenance personnel do not know, they are slightly careless. At this time, when they are exposed to the lighting, there is a danger of electric shock. Therefore, you should pay attention to this when using it.

Compared with the wiring method shown in Fig. 7 and Fig. 8, although the connection method shown in Fig. 8 can save labor and materials, it is very unsafe. The connection method shown in Figure 7 is in accordance with the regulations. If the lamp is replaced or the lamp head is replaced, the phase line power supply can be turned off as long as the switch is turned off, and the lamp head will not be charged, so that an electric shock accident will not occur. In the connection shown in Figure 8, even if the maintenance personnel are checking the lamp head, the switch is obviously disconnected, but sometimes the switch does not disconnect the phase line power supply, so the lamp head will be charged, and an electric shock accident will occur to the maintenance personnel. In addition, in the connection method shown in Figure 8, the phase and zero (neutral line) lines all enter the same switch. If the load power is greater than a certain value, the switching action will generate an arc and the phase zero will be shorted as shown in Figure 9, saving one. The two control switches of the control wire are connected. When the distance between the two locations is long, there are many wires to be used. By connecting four diodes as shown in Figure 9, two double-opening and zero-short circuits can be saved. A wire between the off. The diode withstand voltage should be greater than 400V, and the forward current can be greater than the load current. Connected by the method shown in Figure 9, the lamp is slightly darker than the rated power, but the power consumption is reduced by half, and the life of the bulb is also greatly extended, which is very suitable for stairs and corridors. When there are more than two control points, a double-pole double-throw switch can be installed in the middle of the two double-connected switches. As shown in Figure 10, the wiring method of the three control points is shown. If you need to control at 4 locations, add a double pole double throw switch, as shown in Figure 11. The rest is like this.