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Tiêu chuẩn Nema VE 1

NEMA STANDARD VE 1 is published by the National Electrical Manufacturers Association in the U.S.A. The standard provides for the technical requirements of construction, performance and testing of cable tray systems. It is regularly revised by the Association in order to keep pace with technology and the ever changing requirements of the manufacturers, contractors, consultants and other users throughout the electrical industry.

The more important aspects of the NEMA Standard VE 1 which are relevant to products are described as follows:

1. Load Capacity and Safety Factor

The NEMA VE 1 rating method is based on the Imperial system of measurement.


2. Deflection

The NEMA Standard VE1 does not specify any limitation on the deflection of cable support members. To do so, would inevitably result in an over-designed (and hence uneconomical) system. For further information on deflection please refer to note under Guidelines for Ladder Selection.


3. Electrical Continuity

  • Each specimen shall consist of two 600 mm (24 in.) minimum lengths of standard spliced or coupled sections.
  • A current of 30 Ampere DC shall be passed through the specimen and the resistance measured between two points located 1.6 mm (1/16 in.) from each side of the splice or coupling. The net resistance of the connection shall be not more than 330 micro-ohms (0.00033Ω) as computed from the measured voltage drop and current passing through the specimen, at an ambient temperature of 15 – 35° C (60 – 95° F).

The current source shall be applied at least 300 mm (12 in.) on either side of the splice or coupling.


NEMA Load/ Span Class Designations


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