Switching devices and electrical wires are important electrical equipment that need to be considered when designing a home electrical system. Therefore, you need to choose the installation location as well as install the switching devices properly.
This article will introduce what a switching device is and what types of switching devices there are. In addition, the article also guides you on how to safely install switching devices and electrical wires, helping to ensure the efficient operation of the electrical system, while preventing the risk of dangerous electrical incidents in the home and construction.
Let’s learn how to safely install switching devices and electrical wires in the article below with QNT Investment and Trading Services Company Limited to apply to your home electrical system!
1. What is a Switchgear?
Switchgear is a device used to interrupt or close the current in the electrical system, helping to control, protect and ensure the safety of electrical equipment when problems occur or when maintenance is needed. They include devices such as switches, circuit breakers, circuit breakers (MCBs), air circuit breakers (ACBs), and vacuum circuit breakers (VCBs). Switchgear plays an important role in preventing overloads, short circuits or electrical leakage, helping to protect both the electrical system and users.
2. What types of switching devices are there?
There are many types of switching devices on the market, they are used for different purposes to suit. But in this article, we will mention the following types of circuit breakers: ACB, VCB, MCB, RCCB, RCBO, ELCB, RCD
– ACB (Air Circuit Breaker): Air circuit breaker
– VCB (Vacuum Circuit Breakers): Vacuum circuit breaker
– MCCB (Moulded Case Circuit Breaker): Block circuit breaker, usually has large short-circuit breaking current (up to 80kA)
– MCB (Miniature Circuit Breaker): Shrimp type circuit breaker, usually has low rated breaking current and overload breaking current (100A/10kA)
– RCCB (Residual Current Circuit Breaker): Anti-leakage current type with size of MCB 2P, 4P
– RCBO (Residual Current Circuit Breaker with Overcurrent Protection): Anti-leakage current type with size of MCB 2P with additional overcurrent protection
– ELCB (Earth Leakage Circuit Breaker): Anti-current device leakage, essentially a normal MCCB or MCB with an additional leakage current sensor. This type protects against short circuit, overload, and leakage current, so it is more expensive. There are RCDs in ELCBs that are dozens of times more expensive than normal RCCBs or RCBOs. However, if viewed from the perspective of the circuit and protection principles, it is clear that RCCB and ELCB are completely the same (protection against leakage current – excess current, anti-shock), only different in name and ELCB has the same structure as MCCB (while RCBO only has a shrimp-shaped structure like MCB)
MCCB
RCBO = ELCB = RCCB + MCB (MCCB)
– RCD (Residual Current Device): Is a device that is always attached (additional) to MCCB or MCB to protect against leakage current
3. Main parameters of low-voltage switching devices
– Frequency
– Rated service voltage Ue: Rated working voltage
– Rated impulse withstand voltage Uimp: Rated impulse withstand voltage
– Rated insulation voltage Ui: Rated insulation voltage
– Rated uninterrupted current Iu: Rated breaking current
– Rated ultimate short-circuit breaking capacity LCU: LCU short-circuit breaking capacity
– Rated service short-circuit breaking capacity LCS=%LCU, (about 75% to 100% LCU), can cut the rated short-circuit current
– Rated short-time withstand current Icw: The ability to withstand short-circuit current of the contact for 1s or 3s depending on the manufacturer
4. Distinguishing the application of low-voltage switching devices ACB, VCB, MCB, RCCB, RCBO, ELCB, RCD
– VCB is often used with medium voltage or higher from about 6.6kV
– ACB is often used with low voltage, used for power feeders or large current loads, usually larger than 400A can choose ACB, if smaller then choose MCCB
– MCCB is used with low voltage network, currently MCCB reaches cutting current up to 2400A
– This type of MCB is used for small loads, can cut up to 100A or more
* Note:
– MCCB has two types of fix type and var type, each of which also has two types: TM (Thermal & Magnetic Contact) and MO (Magnetic Contact Only). – – TM type is used for non-motor load, and MO type is used for motor load.
ACB, MCCB, MCB are switchgears in low voltage networks with the most complete functions of a switchgear
QNT Investment and Trading Services Company Limited specializes in providing SIMON switchgears with top quality and reasonable prices. Please contact us immediately for free consultation and quotation.
SIMON switching equipment
5. How to install switching devices and electrical wires safely
1. Electrical wires in the house should not be bare wires but should be insulated with good quality. The size (cross-section) of the electrical wire is selected so that it has enough capacity to carry the current to the electrical appliances it supplies. Wires with small cross-sections should not be used for electrical appliances with too much capacity to avoid causing a fire in the house.
2. Electrical wires in the house are usually installed on porcelain clamps, porcelain pulleys or threaded in protective tubes, which are usually made of plastic.
3. The distance between 2 porcelain clamps or 2 adjacent porcelain pulleys should not be too large, ensuring that the distance between the wire and the architectural object (wall, ceiling, …) is not less than 10mm.
4. When connecting electrical wires, they must be connected alternately and have insulating tape wrapped around the joints (especially double wires).
5. Electrical wires passing through walls and roofs must be placed in protective porcelain pipes. Rainwater must not be allowed to accumulate in the pipes or flow into the house. The distance from the insulators supporting the ends of the electrical wires entering the house to the roof must not be less than 2m.
6. Circuit breakers and electrical switches must be placed in easy-to-operate locations, with no obstructions underneath. The location must be spacious and well-lit, ensuring that when necessary, the power can be turned on and off quickly and promptly.
7. Circuit breakers and electrical switches are usually mounted on small wooden boards and are securely fastened to the walls or pillars of the house. The most suitable location for mounting the wooden boards is about 1.5m above the ground. Circuit breakers and electrical switches must have safety covers. The cover is used to prevent electrical accidents when we accidentally touch it and to avoid electric arcs when turning on and off the power.
8. The main line in the house and each sub-line as well as each electrical appliance in the house must be installed with a protective fuse with a cover. The fuse wire of the protective fuse must be suitable for the capacity used to ensure that when there is an electrical short circuit, the fuse wire must explode, cutting the circuit (remember that the fuse wire is not to protect people from electric shock). The fuse wire must be installed according to the prescribed standards, for example, in a single-phase circuit (1 hot wire and 1 neutral wire), the fuse must be placed on the hot wire. If both wires are hot wires (2 phase wires), the fuse must be placed on both wires.
9. In humid places, especially in the bathroom, do not place electrical outlets, electrical switches, and do not pull electrical wires through this place. For the bathroom, the safest place to put the electrical switch is on the outside of the door, next to the door frame on the side without hinges.
10. If the circuit breakers, switches, and electrical outlets are damaged, they must be replaced immediately, because otherwise, people can easily touch the conductive parts.
11. It is necessary to explain and educate children to understand and not to put metal wires, iron nails or fingers into electrical outlets.
12. Never turn on or turn off the circuit breaker, switch, etc. when your hands are wet because the water on your hands can flow into the electrical parts in the circuit breaker, switch and will transmit electricity and cause electric shock.
13. Absolutely do not use your fingers to test whether there is electricity or not, but use a low-voltage electric tester or a light bulb to determine.
14. When the electricity in the house is damaged, if the damaged part is above the electric meter, you must notify the electric branch to send workers to repair it. Absolutely do not call outsiders who are not electric workers. If the damaged part is behind the electric meter, you must turn off the main circuit breaker before repairing the damage.
15. Only electrical equipment and electrical tools that have been grounded are allowed to be used, and are not connected to ensure safety.
Effects of protective grounding:
– Protective grounding is using an electric wire to connect the metal shell of an electrical device that is normally not energized to a grounded iron or steel object buried underground.
– Protective grounding is applied in a 3-phase network with an isolated neutral, which has the effect of making the electric current when touching the shell – due to a damaged insulation layer (1-phase short circuit), will be transmitted to the ground thanks to the wire connecting the device shell to the grounded object. When touching the shell of such a device, the human body will be considered to be connected in parallel with the grounded object with very low resistance, thus reducing the value of the current passing through the body, so it is no longer dangerous.
Effect of unprotected connection:
– Unprotected connection is to use an electric wire to connect the metal shell of the electrical device when it is normally not energized with the grounded neutral wire of the power grid.
– Unprotected connection is applied in 3-phase 4-wire network, when the current touches the device shell, it will create a 1-phase short circuit current that will blow the fuse or cause the switch to automatically cut off the power at the circuit section of the network or the device is damaged with the smallest short circuit time. To ensure continuous protection even in case the neutral wire is broken, it is necessary to ground multiple times (repeatedly) and it is necessary to ground at the end of the grid.
QNT Investment and Trading Services Co., Ltd. specializes in providing SIMON electrical equipment including switching equipment and electrical wires. We are committed to bringing customers the best quality products at reasonable prices and the most perfect warranty service. Contact us now for free consultation and quotation!
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Showroom address: TM07 My Dinh Pearl 1, No. 1 Chau Van Liem Street, Phu Do Ward, Nam Tu Liem District, Hanoi
Hotline: 0977.566.348
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