Regarding the selection of branch cables
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Currently, flexible tubes are increasingly less used to connect branch cables at the instrument terminals; gland seals are preferred in such cases. Is it necessary for branch cables to be armored cables, and are there any regulatory requirements regarding this?
Flexible pipes don’t need cable glands for sealing; what an idiot.
There are no mandatory regulations for this; it depends on the project’s rules.
This post was last edited by HEJIYUER on 2020-3-13 23:35. There are no mandatory standards. Whether the branch cable is armored depends on the customer’s* preferences and requirements; this relates to the topic of mechanical protection. Back in Europe, there was a saying that \"using high-quality cables eliminates the need for armoring.\" In fact, unarmored versions are indeed used in Europe as well, but large companies generally opt for armored ones. In Europe, small slot boxes are used for wiring, and gland sealing is employed for connections to the equipment. Even when steel pipes are used for wiring, the connection is terminated at the meter box entrance, with gland connections used there. In the United States, steel pipes are commonly used for wiring, with the entire route to the meter box being sealed; insulated seals are used for the incoming cables, while flexible pipes are employed to facilitate piping installation. In Division 1 of the United States, if steel pipes are not used, the cables must be armored, with bellows armor being the preferred type. In China, the theory behind explosion protection comes from Europe, but the wiring practices follow those used in the United States. Now there is a trend toward adopting European standards; Gran is an example of this, and its advantages outweigh its disadvantages.
Domestic design firms use conduit for wiring, while foreign design firms employ instrumentation trays to connect to the grid tray systems. It is then connected to the main cable tray. The installation manual states that 50*50 trough-type cable trays should be used as branch cable trays. The downside of trough-type trays compared to grid-type trays is that it is more difficult to consolidate the cables. Many of the current standards are actually quite old and not clear enough; it seems that the design process is rather chaotic
It is still recommended to use it; later, an “expert” can come and conduct an inspection, which will give a definite result, though the process of making corrections will be lengthy.
Personally, I think armored cable should be used when running directly buried; if it’s run through pipes, unarmored cable is also an acceptable option.