Directly buried wire can? How to install?

 

Is it forbidden to do residential electrical installations on the floor instead of using the walls and ceiling? What does the standard say about electrical cables on the floor? Is it necessary to use any specific type of conduit? What are the advantages and disadvantages of electrical installations on the floor? These are the main questions on the topic of this article and all the answers and many other tips you can see below, come on guys!

Electrical cables across the floor: What does the standard say?

The NBR 5410 standard has a part that deals exclusively with buried cables! Electrical cables can be run through conduits on the floor or even without conduits, as long as they follow some rules. The standard makes it very clear that any cable that is used buried directly in the ground must have mechanical protection and this protection goes beyond PVC insulation.

Within the norm, topic 6.2.11.6 deals with all the details for buried cables. Item 6.2.11.6.1 says that: In buried lines (cables directly buried or contained in buried conduits), only unipolar or multipolar cables are allowed. In addition, on lines with directly buried cables without additional mechanical protection, only armored cables are allowed. Below, the NOTE says that: The use of insulated conductors in a buried conduit is allowed if, in the buried section, there is no buried passage and/or branch box and the conduit is watertight.

Therefore, for residential installation, it is permitted, but if ordinary insulated cables are used, there can be no through a box on the floor, no bypass, and no liquid infiltration.

Does the standard allow the installation of cables directly buried in the floor?

Electrical cables on the floor: Unipolar and multipolar cables!

In cases where unipolar and multipolar cables are used directly buried in the ground without conduit, these cables must be protected against the deterioration that can be caused by earth movement, contact with tools in case of excavation, against humidity, contact with structures and actions chemicals that may be caused by elements in the soil.

In the case of normal land, the installation must have a minimum depth of 70 cm from the ground and if it is a land with car access, such as a garage, this depth must increase to 1 m from the ground with extra strips 50 cm wide on one side and the other on the roadways for vehicles, as shown in the following drawing.

Example of installing wire buried in the ground according to the standard

If there is a crossing between buried electrical lines, there must be a minimum distance of 20 cm between them, this distance of 20 cm must also occur in the case of an electrical line with any other type of line such as internet network cables, as shown in the image below.

Example of buried wire crossing according to NBR 5410

Electrical cables on the floor: How to signal?

According to the standard, it is necessary to have a sign 10cm above the line to serve as a reference in case of an excavation. In this way, before reaching the line, it will be possible to see the signs and avoid possible accidents. To do this signaling, you can use a colored ribbon that will not deteriorate over time.

Electrical cables on the floor: What are the disadvantages?

The disadvantages with respect to cables on the floor start with the number of extra rules that the standard establishes. In the case of directly buried cables, the price of the unipolar cable is higher than the insulated cable. Another negative point is if there is a need to change a buried cable directly or to change a conduit that is under a finished floor, in this case, the price will certainly be much more expensive than cutting in a ceiling or wall.

Electrical cables on the floor: What are the advantages?

Among the positive points, we can mention that during the work of laying cables in conduits on the floor, the laying effort is much less and the possibility of falls from stairs is eliminated. It is also possible that there will be savings in the number of cables, but this will depend a lot on the design and path of the conduits, in addition to the positions of the socket boxes, etc.

So we finished this article and hope to have answered the questions about cables and conduits on the floor. If you have any questions, leave them in the comments and we will be happy to answer them.