How many wires are there to enter the factory building and workshops? ?
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Do people use 4 or 5 wires for the power wiring?
If there is a reliable network grounding inside the workshop, a 3-phase 4-wire system is used; otherwise, a 3-phase 5-wire system is generally adopted.
This depends on the type of grounding system chosen by your company. In the case of TN-C and TN-C-S, there are 4 wires for the incoming connection ； If it is TN-S, there are five wires for the incoming connection.
According to the regulations, if your factory’s power equipment is to use neutral grounding protection, a three-phase four-wire system must be employed, and the equipment must be equipped with such protection. If grounding protection is used for the equipment, a three-phase four-wire or five-wire system can be employed, depending on the design; however, electrical equipment must only be provided with grounding protection, and it is not allowed to use both grounding and neutral grounding protection together. The three-phase five-wire system is generally used for indoor power distribution to ensure electrical safety.
If the factory building is equipped with a transformer, it is recommended to use the TN-C-S system for the low-voltage system (also known as the three-phase five-wire system). If the power supply entering the workshop comes from another source via a TN-C system (i.e., the three-phase four-wire system), it is advisable to convert it to a TN-C-S system once it enters the workshop.
It is usually 5 wires, as low-voltage systems are generally TN-S systems
According to the book, the TN-S system is suitable for workshops with separate substation facilities, while the TN-C-S system can be used in areas within the factory complex that have substations or low-voltage power supply lines, as well as in residential buildings. Use this as a guide to make your selection.
The power supply that is used in factories is usually three-phase four-wire; if the instruments used within the factory require high precision, then three-phase five-wire is a better option. It also depends on the quality of the grounding system in the factory – if it’s good, then three-phase four-wire is sufficient, and there’s no need for three-phase five-wire.
It depends on your needs; our factory uses a three-phase four-wire system
The transformer outlets all have four wires, but the distribution room is equipped with a ground wire; wires 3, 4, and 5 are connected to the equipment, depending on the requirements
Currently, there are grounding points around low-voltage equipment; the enclosure of such equipment can be connected directly to these grounding points for protective grounding. The low-voltage power wiring consists of 4 wires: three phase wires and one neutral wire. If there is no grounding point around the low-voltage equipment, and the enclosure of the low-voltage equipment does not have the possibility of on-site grounding, and the low-voltage power wiring consists of 4 wires – three phase wires, one neutral wire, and one ground wire – then this is a TN-S type grounding system.
In the TN-S system, the N wire and the PE wire are connected at the transformer, and they cannot be connected again after that. I think a five-core cable should be used when entering the factory building.