This topics always discussed among of electrician personnel that involved on new installation or electrical projects.If they miss calculated or choose a wrong size for the conductor/wires,it’s can cause a big disaster when that installation failure.
Electrical cable/wire is a important things that we must consider with calculation and detail discussion to avoid any mistaken during design and installation.We must take a serious action to get a good result.
I would like to shared some general requirement for electrical cable/wire for new electrical installation or projects that we must consider during design review.I hope this can make a guide line for the best result in your installation or projects.
Wire Size and Specification
Note: The NEC sections referenced below generally meet or exceed the requirements of IEC/EN 60204-1 Safety of Electrical Machinery – Electrical equipment of machines – Part 1: General requirements, Table 6 – Minimum cross-sectional areas of copper conductors.
1) Minimum wire size shall be determined by following the NEC (National Electric Code) regardless of the destination of the machine/process skid.
When following the NEC, see the following [NEC Table 310.5] exceptions that are noted below:
A. Flexible cords and (flexible) cables: [NEC 400.12, Table 400.4]
B. Motors rated 1 hp or less as permitted by NEC 430.22(F)
C. Control and instrumentation circuits as permitted by: NEC Article 725.27(A). Note: most instrument and control circuits are Class 1 circuits – NEC Article 727.6
D. Motor control circuits as permitted by NEC 430.72
E. Data communication circuits as permitted in NEC Article 800
F. Or as otherwise specifically allowed in the NEC
2) All wire shall be dual rated or “harmonized” wire. Wire sizes shall be AWG (American Wire Gauge). Use the conversion table 1 “Conductor Properties”, Chapter 9 of the NEC or Table D.1 in Annex D of IEC 60204-1 to convert to metric units for Europe. Size wires to use the next larger AWG for “in between” metric sizes. (chart for cross references between sizes located to the left)
3) Individual conductors shall be multi-stranded, copper wire with a 600V minimum insulation rating. In general, all wiring shall be type THHN/THWN – 90 degree, which is suitable for wet or dry locations.
Note: Olflex and SAB are global suppliers for dual-rated wire and cable, and offer “quad-rated” or “harmonized” wire and cable. Pre-Approval by the AHJ in a specific location could allow the use of wire vendors not on this list. It is critical to get approval before the machine is wired to prevent major cost and schedule implications on the project.
Cable Size Converter – AWG & Metric
Standard Color Code for Electrical Wiring.
Identification of Conductors
1) All wires shall be tagged with a permanent, legible label and marked identically at both ends.
2) Adhesive tape type labels are not acceptable, as experience has shown that they readily fall off.
3) Conductors shall be identified at each termination by number, letter, color (either solid or with one or more stripes), or a combination thereof and shall correspond with the technical documentation.
4) Where letters are used to identify conductors, they shall be capital block letters. Numbers shall be Western style numerals in block style.
5) Internal wiring on individual commercial devices purchased completely wired shall not require additional identification.
6) Individual conductors derived from multi-conductor cables shall not be required to meet the color code requirements but shall be alpha numerically identified consistently at both ends.