For the vast majority of electricity professionals, the color of electrical cables and their functions are well defined and it is a rule. The big problem is when we deal with cases in which the professional is not qualified or the customer is responsible for the purchase of cables, in both cases, they usually opt for what is at hand or what is cheaper. There is a big question that even includes good professionals, about the obligation to always use cables with colors defined by function, or if there are other forms of identification! It is important to stress that there is a technical standard that specifically speaks about this particular subject.
Standard NBR-5410 – Low voltage electrical installations
This Standard establishes the conditions that low voltage electrical installations must satisfy, in order to guarantee the safety of people and animals, the proper functioning of the installation and the conservation of the property.
The standard applies to low voltage electrical installations in buildings, specifying rules such as cable colors, their identification and function, residential grounding, lighting, sockets and switches, location of the distribution board, load-lifting, and many other items.
According to the standard, it is not mandatory to use colors to identify cables. Other methods can be used to identify the function of the cable, the use of washers with letters, words and symbols is an alternative. The standard is very clear, but if color is used as a way of identifying the function, these colors should follow the pattern below: like this:
Any insulated conductor, unipolar cable or multipolar cable vein used as a neutral conductor, in case of color identification, the light blue color should be used in the insulation of the insulated conductor or the vein of the multipolar cable, or in the cover of the unipolar cable.
(NBR 5410: 2004 item 184.108.40.206.1).
NOTE: The vein with light blue insulation of a multipolar cable can be used for functions other than the neutral conductor, if the circuit has no neutral conductor or if the cable has a peripheral conductor used as neutral.
Observe this excerpt from the standard, “in case of identification by color”, indicates that other forms of identification can be used. Therefore, the first words of this excerpt “any conductor” show that it can be any type of conductor. Logically, all technical criteria for cable sizing must be taken into account so that the conductor is chosen for the function. The following sections of the standard extend the same rule to all other cable functions.
Any insulated conductor, unipolar cable or vein of multipolar cable used as a protective conductor (PE), in case of identification by color, the double yellow-green color or the green color (colors exclusive of the protection function) must be used in the insulation of the insulated conductor or the vein of the multipolar cable, or in the cover of the unipolar cable.
(NBR 5410: 2004 item 220.127.116.11.2).
Protective Earth Conductor or PEN
Any insulated conductor, unipolar cable or multipolar cable vein used as a PEN conductor must be identified according to this function. In case of color identification, light blue color, with green-yellow washers in visible or accessible points, should be used in the insulation of the isolated conductor or the vein of the multipolar cable, or in the cover of the unipolar cable (NBR 5410: 2004 item 18.104.22.168.3).
For the phase conductor, any colors can be used as long as you do not use the colors established in the previous items. Any insulated conductor, unipolar cable or vein of multipolar cable used as a phase conductor must be identified according to this function. In the case of color identification, any color can be used, observing the restrictions established in 22.214.171.124.1, 126.96.36.199.2 and 188.8.131.52.3.
NOTE: For safety reasons, the exclusively yellow insulation color should not be used where there is a risk of confusion with the double yellow-green color, colors exclusive to the protective conductor.
Another alternative to identify cables according to their function is to use colored insulating tapes. When using an identification alternative other than the insulation colors of the cables, such as electrical tape or banding, this identification must be made at all visible points of the cables and at the access points such as cable boxes and cable terminations.
Definitely colored cables in their insulation used correctly are the best way to identify electrical cables and their function, but unfortunately, this is not the reality of all electrical installations. Standardization (use of standards) in electrical installations is very important, it aims at safety and optimal and regular use of the installations.
Although this information is not disseminated to all professionals who deal with electrical installations, the standard allows the use of various forms of cable identification according to their function, but even these alternatives follow what the standard dictates