Standard wiring practices is a basic guidelines for Electrical Engineer or Electrical Technician when involve in Electrical installation project.From the guideline,we can minimize the electrical safety issues,have a proper electrical route and more tidy installation and follow standard requirement.
Actually I had involved in many of Electrical installation projects and this standard wiring practices guide me a lot to get a best quality and perfection on my Electrical Installation project.Below I had listed some beneficial guideline when do you have a Electrical Wiring Installation.I hope it’s can give some basics information or guide to get a best result.
Standard Wiring Practices for Electrical Installation
1) For multi-conductor cables, there may be additional conductors within these cables that are not needed or used for the application. All unused conductors within the multi-conductor cable shall be bent back and taped. The conductors shall not be exposed.
2) Motor cables shall run continuously from one piece of apparatus to another with no splices in between. Junction boxes with terminals may be used for control wiring as a means to connect or extend cables on the machine.
3) If the machine is so constructed that cabling shall be disconnected for shipment, plugs or terminal strips shall be provided at the sectional points.
4) For power cables, no plugs are permitted unless approved by the Electrical Engineer. Use terminal strips or leave sufficient lengths of power cables on the machine that can be terminated to the machine power source(s) in the field are other acceptable means for power cables.
5) The supplier shall not route power and signal conductors in close proximity of one another unless approved by the Electrical Engineer.
6) The supplier should keep a minimum separation between power and signal conductors per the following table. If these separations cannot be maintained, the Electrical Engineer shall be consulted. Where power and signal conductors are required to cross, the lower voltage conductor should cross the higher voltage conductor at right angles.
Minimum Separation Distances between Twisted Pair Signal Wires and AC Power Lines
7) Terminal blocks shall be grouped by signal, power and safety.Only one wire shall be connected to a terminal, unless the terminal/device is rated for multiple wires.
8) Shield on cables shall be grounded per the equipment suppliers or manufacturers recommendations. Vendor recommendations and wiring practices will be reviewed with the responsible Electrical Engineer prior to implementation.
9) All terminal strips are to be located within the enclosure in such a location as to make them readily accessible.
10) All terminal strips, terminals and wires shall have unique identification, shall be clearly labeled and shall match the equipment documentation. Wires shall be labeled identically at both ends.
11) Electrical conductors at voltages above 50VAC/DC shall not be run through equipment frame members as this is a violation of the NEC and presents a safety concern if the equipment frame is cut, drilled or torched into.
12) In the event that cables at voltages below 50VAC/DC such as sensors or guard switch cables enter into a frame member, a label shown to the left shall be placed on the frame member in a location clearly visible from the normal operating location.
13) Bends in cables shall be made so as not to cause undue stress. Radius of the curve (measured from the inside edge of the bend) shall not be less than five times the diameter of the cable.
14) Any conductors that occupy the same equipment enclosure, cable, or raceway shall have the same insulation rating as the maximum circuit voltage applied to any conductor within that enclosure, cable or raceway – Reference NEC Article 300.3(C)(1). In addition, supplemental or double insulation will also have to be used per the requirements of IEC-60664-1.