Electric plumb, what is it and how to interpret?

Do you know how to install interconnected QDC’s in a building? In this article, the World of Electrical talks about what an electric plumb is, shows how the reading is done and what is its importance. Come on, guys!

A very frequent question is how to install an interconnected QDC’s in a multi-story residence. To understand well how to do an installation of this type, it is important to first know how to read electrical projects, because in the case of installation of this size an electrical project is necessary. And within the design of a multi-story building with several apartments will be the design of the electric plumb.

What is an electric plumb?
The electric plumb is the drawing of the diagram that represents the electrical installation in the vertical plane. This drawing shows the interconnection of the entire installation, basically containing a disconnecting box, general low voltage supply, general low voltage switchgear, meter center, passage boxes, partial switchboard and terminal board feeders.

The electrical plumb is not a diagram, as it does not show wiring diagram.
What is an electric plumb?

The plumb allows a clear understanding of the interconnections existing between the different floors and sectors of a building or installation, and quick identification of the gauges of the conduits and the conductors that interconnect them. The electrical plumb is not an electrical diagram, as it does not show a wiring diagram, that is, it shows the distribution of conduits and boxes.

How to read an electric plumb?
Interpreting an electric plumb is not always an easy task, but it is always important to be informed. Thinking about it, we separated an electric plumb from a four-story building and underground, to teach how to read an electric plumb. In the image below we have to plumb our example, and a table explaining exactly where it starts and where it goes each conduit. Also note that plumb each conduit section receives a letter, and to facilitate the identification put the meaning of each acronym.

Table explaining exactly where each conduit starts and how far it goes.
Electric plumb of a four-story building and basement.

The first question that electricians have is about the acronyms that appear on the boards, for example, QGBT (general low voltage board) or QF (power board), in addition to many other acronyms that may appear. As there is no standard for the standardization of these acronyms and they are not always described in a project, it is natural to arise doubts.

The interpretation of the plummet starts at the conduit A (underground feeder branch), which starts at the connection point with the concessionaire and goes to the disconnector box (CS), which is an inspection box for the connection of the installation’s input cables. Then, the conduit B (general low voltage feeder), goes from the disconnecting box to the QGBT (general low voltage panel). This initial sequence of plumb varies according to the energy utility.

This initial sequence of plumb varies according to the energy utility.
Disconnecting box and general low voltage switchgear.

Continuing we have the conduit C (feeder of the meter center), goes from the QGBT to the CM-01 (measuring box), the 01 is the standardization of the size and model of the box. There are several other sizes of CM that can be used according to need and dealership. From the meter box, distribution to the floors and the condominium begins. The conduit D (feeder for QL’s 101 to 104), feeds the first floor, it goes from CM-01 to CP-02 (pass box). Right after the CM-01, we have the CP-01 which is used for interconnecting cables and for passing condominium cables. Conduit D passes CP-01 and ends at CP-02.

From the meter box, distribution to the floors and the condominium begins.
Measuring box, standardization of the box size and model.

Then the conduit E (feeder for QL’s 201 to 204), feeds the second floor, going from CM-01 to CP-03, going through CP-01 and CP-02. The F conduit (feeder for QL’s 301 to 304), feeds the third floor, runs from CM-01 to CP-04, through CP-01, CP-02, and CP-03. The G conduit (feeder for QL’s 401 to 404), feeds the fourth floor, leaving CM-01 to CP-04, passing through CP-01, CP-02, CP-03, and CP-04.

QL’s 201 to 204 feeder.
Floor feeds.

Conduit M (generally above the feeder condominium), feeds the condominium following CM-01 to the HQ-C (general framework condominium), exiting in conduit I (terminal frame handler – ground), which will HQ -C to QL-CT (light panel of the ground floor condominium). Then the J conduit (terminal board feeder – underground), goes from the QG-C to the QL-CS (light panel of the underground condominium). The conduit K (terminal board feeder – engine room), goes from the HQ-C to the QF-CM (engine room power board), passing through CP-01, CP-02, CP-0