How many poles should switches for maintenance power and drive power have?
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In all the projects I’ve worked on before, three-pole switches were used for the maintenance power and power supply boxes in the distribution rooms. On one project, I saw four-pole switches being used for both maintenance and power supplies. Is there any mandatory requirement for this? Which standard clause specifies it?
Note: The first drawing was taken with the drawer pulled out； The second image shows the wiring after the disk is installed
All power feeders these days are required to have leakage protection, so they are 4-pole; we hope colleagues from design institutes can provide an answer regarding the standards
For the outlets in the maintenance box, each circuit is equipped with a leakage protector; three-level power distribution with two levels of leakage protection is sufficient, so there’s no need to add another level in the power distribution room.
I have consulted experts in electrical engineering from renowned domestic chemical engineering design firms; a four-pole switch is not necessary – it represents excessive caution and leads to additional costs!
Let’s give this post another boost. The issue is that it’s not clear which devices and locations require leakage protection. According to Article 4.5 of GB13955, electrical equipment used in production must be equipped with residual current protection, and this covers a wide range of devices. Is it true that in modern designs, leakage switches or RCD protection are basically installed everywhere? Many feeders cabinets come equipped with RCD leakage protection, as do on-site electric heaters, lighting fixtures, etc. What would the professionals from design firms say about this?
According to clause 4.5 of GB13955, it is specified that in areas where residual current protection must be installed, all electrical equipment used in production must be equipped with such protection. It should be noted that it is to be installed at the end, at the on-site terminal switch; there is no need to install it in the distribution room’s feedout cabinet.
Isn’t the end of the motor cable in the distribution room?
The outlet end of the motor is located in the motor junction box, while the distribution room is at the starting end
This is rather far-fetched. Taking temporary power supply as an example, the \"end point\" refers to the protection provided by the switch box; therefore, it should denote the switch right before the electrical device. This concept is understood from the perspective of the system diagram, not from a spatial standpoint. The main problem is that our national standards remain too vague