⚡️ FREE CLASS: How to Do a Complete Electrical Installation from Scratch, Easily, Even if You Are Not a Professional Electrician: ➽ https://eletr.co/aula?utm_content=xEW... ------ ???? FAAALA ENGEHALL COMMUNITY ???? Join our community on WhatsApp to receive valuable tips and news in the electrical area, important information and much more. ???? ???? https://eletr.co/fala-eng ------ Did you like this video? ???? ✔️ Leave your comment and share with your friends ✔️ Follow our networks ➽ https://eletr.co/links - - - - - - - - - - - - - - - - - - - - - - - - - - - - ???? NR10 Course with 20% discount ➽ https://eletr.co/nr10?utm_content=yt1... ------ Hey my dears, how are you? Look... if you think that grounding is a simple thing, I'm sorry to tell you that it won't always be that way. Poorly done grounding puts your installation at risk, especially when it comes to TT grounding, the type of grounding that causes a lot of discussions among professionals in our field. Now, if you still don't know what TT grounding is and/or don't know that the way to connect SPDs in this grounding scheme is different from other schemes, you have to stay with me until the end of this lesson, because I've prepared a complete and amazing explanation so you can understand it once and for all. First of all, let's call a spade a spade: After all, what is TT grounding? Well, in short, TT grounding (or TT scheme if you prefer) is one in which the equipment is grounded with a special rod, different from the rod used to ground the neutral, that is, in this scheme the points are not equipotentialized. As I said, it causes a lot of discussions. And the blame for many of these discussions lies with the NBR-5410 standard itself, which contradicts itself in some points, for example, in item 5.1.2.2.3.3 it states that “All the installation masses located in the same building must be connected to the main equipotentialization of the building.” So I always wondered, if that’s the case, how is a grounding that is not equipotentialized allowed? Remembering that the standard mentions TT grounding, but anyway, we are not here to question the standard, despite these contradictions, we must follow what it determines, right? But that’s the thing, if you opt for TT grounding, that is, one that is not connected to the neutral at any point in the power supply, the way to connect the DPS changes, and then comes the first question for many electricians: WHERE TO INSTALL THE DPS? BEFORE OR AFTER THE DR? Well, item 6.3.5.2.2 of NBR 5410 states that DPSs must be installed as close as possible to the entry point, HOWEVER, they must be arranged as shown in Figure 13. So let's see what it says in Figure 13: "Does the power line that reaches the building include the neutral?". YES: "Is the neutral grounded at the building's main equipotential bonding busbar?". Most buildings do not have this busbar, so let's go down the path of NO. Note that there is a lowercase letter c. Let's see what it says: The hypothesis configures three possibilities for grounding schemes: TT (with neutral), IT with neutral, and the line that enters the building already in a TN S scheme. Following, we see that there are 2 possible connection schemes. But notice that we have a letter again, this time a lowercase d. Let's see what it says: There are situations in which one of the two schemes becomes MANDATORY, such as the case related in paragraph b) of 6.3.5.2.6. AND WHAT DOES THIS ITEM SAY? “when the DPS are installed, as indicated in 6.3.5.2.1, next to the entry point of the power line into the building or in the main distribution panel, as close as possible to the entry point, and the installation is equipped with one or more DR devices, the DPS can be positioned upstream or downstream of the DR device(s), respecting the following conditions: when the installation is TT and the DPS are positioned upstream of the DR device(s), the DPS must be connected according to scheme 3 (see figure 13); OOPS! in this case then we MUST adopt scheme 3 of figure 13! In practice, it will look like this, take a look: We have here a practical QDC, with the ground and neutral busbars, and we will add the protection devices, 3 DPS (two phases plus neutral), a bipolar circuit breaker and a tetrapolar DR for illustration purposes only. Let's start with the phases. The two phases arrive and feed the general circuit breaker, they leave the general circuit breaker and branch off to feed the two phase DPS and also the two phase terminals of the DR.