29-April-2022 || By: Admin
Not planning for the future
When you’re determining your cable count for today’s needs, you ought to also calculate what your future demands are going to be . Communication and electrical pathways are stable components and have life expectancies far greater than that of the cabling system they contain. And as systems still converge and expand with new emerging applications, the quantity of cables you’ll need is for certain to grow. It is more time- and cost-efficient to put in a bigger cable tray now then to upgrade your network infrastructure later.
Not supporting the cable tray correctly
The failure to properly install a cable tray may result in safety implications starting from a failure to properly secure the cables to a complete collapse of the trays. VE2 may be a National Electrical Manufacturers Association (NEMA) standard that outlines cable tray installation practices. Section 3: “Installation” describes the various sorts of supports also as details on the way to install them. Key areas like where to locate supports for straight sections and fittings also as where to locate splice joints also are covered. In VE2, the quality provides charts that calculate how often expansion joints are required and the way to properly set the gap for expansion connectors also as locations for hold down clamps and expansion guides.
Improper choice of cable tray
There are many various sorts of cable trays available, from ladder to ventilated trough to wire basket to solid bottom. Knowing the sort of cable and therefore the environment during which it'll be installed will determine the selection of cable tray you would like . For example, single conductor cables must be installed during a ladder or ventilated trough. Solid bottom trays would only normally be specified where EMI/RFI shielding protection may be a concern. Low voltage telecom cables, control and AV cables are traditionally placed in wire basket cable trays. Weight capacity and cable volume of the tray must be calculated so as to specify the right tray criteria. Trays requiring greater span distances would require a greater cross sectional area for the side rails. It’s vital that you simply fully understand all aspects of your installation so as to understand which cable tray will do the simplest job.
Incorrect grounding and bonding
Aluminum and steel cable tray systems are excellent equipment grounding conductors as long as they're properly designed, installed and inspected. These sorts of cable trays are permitted to be used as an equipment ground conductor (EGC), per NEC 392, when labeled intrinsically also as marked with the available cross sectional area. If the cable tray is to be used as an EGC, bonding jumpers must be placed on both side rails at each tray joint, unless the splice plates meet the electrical continuity requirements of NEMA VE1. If the tray connections are UL Classified, bonding jumpers or continuous ground components aren't required. It is important that the grounding of cable tray systems, including the cables within the tray, is inspected before the cabling within the tray is energized and before cable is installed. This will help to eliminate any dangerous situation which will occur thanks to improper bonding.
Calculate a proper fill ratio for the cable tray you are using
Overfilling a cable tray can cause poor cable performance, damage and will become a security hazard. NEC 392.20-22 outlines the wants for installing cables within cable trays by taking the dimensions , voltage and numbers of conductors under consideration so as to develop the right fill ratio of cables in reference to the tray’s cross sectional area. Where low voltage communication cables are used typically either a 40 or 50% rule is in effect. For electrical cables it becomes far more stringent thanks to questions of safety related to higher voltages. Typically, the sum of the diameters of all single conductor cables shall not exceed the cable tray width, and therefore the cables shall be installed during a single layer.
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