## Tuesday, May 14, 2024

This is the problem most ignored by Electricians

My dear, if you are an electrical professional, you have certainly experienced the following situation: You took the multimeter to measure the voltage at an electrical point, and instead of detecting 127v or 220V, you found a voltage much lower than that, perhaps a little more. 100 or 200V….

Well guys, this is a classic problem caused by circuit distance or even sizing error, this problem is called voltage drop, so in today's FLASH TIPS here at Engehall, we're going to talk more about the fact that many electricians ignore this problem and we're going to teach how to do the right calculations so everyone can learn how to protect themselves about this, let's go to class?

Before starting the class, I want to give you a warning:

For many “professionals”, talking about voltage drop is “idle talk”. Many, many, ignore this factor and think that it does not affect the sizing of cables and, as a consequence, conduits as well. Here comes the warning: Not calculating the voltage drop can complicate your entire project and cause enormous inconvenience for your client, and of course I will explain why!

Voltage drop is an effect caused by an increase in the distance traveled by electric current in a circuit. The longer the length of the conductor, the more difficult it will be for the electricity to travel along this path and the greater the voltage drop will be. For this, effective sizing makes all the difference when calculating.

Okay, but in practice what happens with a long circuit that is suffering a voltage drop:

The most common effect is overheating of the cable caused by resistance to the passage of electric current.

1 - We know that there is no material that is 100% conductive,

2 - We also know that copper has its limits for conducting electrical current.

Therefore, for each type of material there is a limit that will create resistance to the passage of electric current, even if it is minimal, which we call resistivity.

But is there any acceptable limit that can have a voltage drop?

Well, the good news is that there is, in item 6.2.7 of NBR-5410, there is a detailed explanation, talking about delivery points and everything else.

But here comes my recommendation as a design engineer! I have always adopted the following numbers in my projects:

Single-phase systems 127V or 220V - Allowable voltage drop 3%;

Three-phase systems 220V or 380V - Allowable voltage drop 5%;

Basically it's a rough way of summarizing what's in the standard, but in my opinion, besides being a conservative number, it's applicable to 90% of electrical projects, which is why I adopted this standard.

Now, how do professionals calculate a voltage drop?

Currently, project software already calculates all of this for us. The official software we use at Engehall is Pro-electrica from Multiplus.

But don't despair, if you don't have software, in this video we will teach you how to use a formula to calculate the voltage drop!

This is the problem most ignored by Electricians

My dear, if you are an electrical professional, you have certainly experienced the following situation: You took the multimeter to measure the voltage at an electrical point, and instead of detecting 127v or 220V, you found a voltage much lower than that, perhaps a little more. 100 or 200V….

Well guys, this is a classic problem caused by circuit distance or even sizing error, this problem is called voltage drop, so in today's FLASH TIPS here at Engehall, we're going to talk more about the fact that many electricians ignore this problem and we're going to teach how to do the right calculations so everyone can learn how to protect themselves about this, let's go to class?

Before starting the class, I want to give you a warning:

For many “professionals”, talking about voltage drop is “idle talk”. Many, many, ignore this factor and think that it does not affect the sizing of cables and, as a consequence, conduits as well. Here comes the warning: Not calculating the voltage drop can complicate your entire project and cause enormous inconvenience for your client, and of course I will explain why!

Voltage drop is an effect caused by an increase in the distance traveled by electric current in a circuit. The longer the length of the conductor, the more difficult it will be for the electricity to travel along this path and the greater the voltage drop will be. For this, effective sizing makes all the difference when calculating.

Okay, but in practice what happens with a long circuit that is suffering a voltage drop:

The most common effect is overheating of the cable caused by resistance to the passage of electric current.

1 - We know that there is no material that is 100% conductive,

2 - We also know that copper has its limits for conducting electrical current.

Therefore, for each type of material there is a limit that will create resistance to the passage of electric current, even if it is minimal, which we call resistivity.

But is there any acceptable limit that can have a voltage drop?

Well, the good news is that there is, in item 6.2.7 of NBR-5410, there is a detailed explanation, talking about delivery points and everything else.

But here comes my recommendation as a design engineer! I have always adopted the following numbers in my projects:

Single-phase systems 127V or 220V - Allowable voltage drop 3%;

Three-phase systems 220V or 380V - Allowable voltage drop 5%;

Basically it's a rough way of summarizing what's in the standard, but in my opinion, besides being a conservative number, it's applicable to 90% of electrical projects, which is why I adopted this standard.

Now, how do professionals calculate a voltage drop?

Currently, project software already calculates all of this for us. The official software we use at Engehall is Pro-electrica from Multiplus.

But don't despair, if you don't have software, in this video we will teach you how to use a formula to calculate the voltage drop!