Measuring Parallel Conductors – Continental Control Systems, LLC.
3 phase parallel feeders free
Parallel conductors are often installed where large ampacity feeders or services are used. Total understanding of the paralleling requirements permitted in the National Electrical Code is necessary before attempting to design a large electrical system or install these conductors. Section Where used as parallel conductors, the circular-mil areas of these conductors are added together to provide the total cross-sectional area for the overall size of the parallel conductors.
These parallel conductors can be used as phase conductors, neutral conductors or grounded conductors. Be careful though, since one of the primary concerns when installing parallel conductors is ensuring that each conductor in the paralleled set has the same electrical characteristics as the others in the same set. All of the paralleled conductors in each phase, neutral or grounded set must be the same length and be made from the same conductor material.
They must be the same circular mil area and have the same type of insulation. Finally, all parallel conductors must be terminated in the same manner. This ensures that each conductor in the parallel set will carry the same amount of current. However, one-phase, neutral or grounded circuit conductors are not required to have the same physical characteristics as those of another phase, neutral or grounded conductor. Any taps made to the paralleled sets of conductors must be made to all the conductors in the set, not just one.
Tapping only one of the conductors in the set could result in an imbalance with one of the conductors carrying more current than the other, resulting in heating of that one conductor and possible insulation damage or failure.
For example, if three kcmil conductors are run per phase, a tap from that particular phase must be a tap from all of the kcmil conductors, not just one of the set. This would require a common terminal point for all three parallel conductors with a tap conductor connection to the common terminal. Where paralleled conductors are run in separate raceways or cables, the raceways or cables must have the same physical characteristics.
For example, if there are four kcmil conductors in a paralleled set of phase conductors, the four separate raceways enclosing the conductors must be all rigid steel, all IMC, or all PVC, etc. If the raceways were of different characteristics, such as three rigid ferrous metal conduits with one rigid nonmetallic conduit, the conductor in the PVC raceway would carry more current than the conductors in each of the metal raceways.
This would result in more impedance in the conductors within the ferrous metal raceways than in the PVC raceway. The higher current in the conductor in the PVC raceway would result in possible overheating of the conductor and insulation damage. Each phase and each neutral or grounded conductor must be present within each separate raceway, auxiliary gutter, cable tray, cable bus assembly, cable or cord. There is an exception to this general rule located in Care must also be taken for compliance with Section Mark C.
Ode ul. Don’t worry, we’ll come to you. By Mark C. Code Applications. National Electrical Code. About the Author. Sign up and Get Connected. Related Stories. Line Contractor. Next Up. Read the Article. All rights reserved. Electrical Contractor Magazine.
– Ampacity Calculator – Cerrowire
Apr 01, · Ampacity 3/0 THHN is A [Table at 90°C) Adjustment factor [Table (B) (2) (a)] = Adjusted ampacity = A × Adjusted ampacity = A. For this scenario, you could not use 3/0 THHN in parallel in the same raceway because the combined ampacity is only A (A × 2), which is not permitted to be protected by a A Missing: free. 1 Power Factor is assumed to be 2 Temperature Rating assumed to be 75°C. 3 Weights are approximate and do not include insulation weights. 4 Values Per feet. 5 Maximum length is based on a load that is 80% of the fuse g: free. Section (B)(1) deals with parallel conductor installations and the reference within this section to provides permission for parallel conductors to be installed separate from each other. Each phase and each neutral or grounded conductor must be present within each separate raceway, auxiliary gutter, cable tray, cable bus assembly Missing: free.