Welded seams or non-welded seams?

Is a welded splice better than a welded splice? Which splice do you trust more, simple splice or tin splice? Will these amendments behave differently in the event of a short circuit? In this article we are going to show you a test in practice, of spliced ​​cables made with solder and without solder, to see what happens with the splices. So come on guys.

Splicing of cables and wires with tin and without tin generates a great discussion among electricians. There are electricians who do not give up welding with tin at the seams, other electricians do not use it because they say it is prohibited.

For electricians who think that splicing with tin is prohibited, in the part of connecting conductors of the NBR 5410 standard, there is an item that addresses this theme. In the note of item 6.2.8.2 it says that: “it is advisable to avoid the use of soldered connections in power circuits. If such connections are used, they must have resistance to creep and mechanical stresses compatible with the application. ” When the standard says “Advisable to avoid” it is not prohibiting the use of welded splices.

Welded seams x Weldless seams

Regardless of this whole discussion, our goal is to test both amendments in the event of a short circuit. The idea of ​​these tests is not to see who breaks first, but whether we are going to notice a big difference between one amendment and another.

To perform our tests we will use a “short circuit machine” that is capable of supplying 300A. First, we will short-circuit a tin-free flexible cable splice. The cable heats up a lot and resists only a few seconds until it breaks, but the seam does not heat up to the point that it is as glowing as the cable.

Then we will repeat the test on a splice with flexible cable and tin. As we apply a very high current, the cable resists only a few seconds, the tin flow is bubbling and the tin itself melts.

Test as flexible cable, splice as and without tin.

Rigid Wire

For the avoidance of doubt, we will repeat the same tests on the rigid wire. First a tin-free seam on the rigid wire. As in previous tests on the flexible cable, the splice itself does not heat up to the point of glowing.

In the test of the splicing of rigid wire with tin, two curious things happened, one is that you could see the tin melted perfectly and bubbling, in addition to the wire breaking in two different points.

Test as rigid wire, seam as and without tin.

One of the conclusions we can draw from these tests is that the time that the cables can withstand in a short circuit between the splice with or without tin is no different, to the point of being an advantage or disadvantage. When testing with two splices together, the time to break is longer as the current is split between the cables, so the splices have heated up to the point of glowing.

Another conclusion is that in no test the splice point was the point where the cable broke, and that is because in that point of the splice, due to the greater amount of copper overlapping the material has a different resistance.

The big difference with tin splices is that they are more mechanically resistant in case of poorly made splices. This is because the tin alloy ends up joining the cables, but as we saw from the tests, in the case of a short circuit there was no big difference that really disapproved the use of tin in the amendments.

The Electrical World is always looking to bring content, which generally causes controversy among electricians. In this video from the Mundo da Elétrica channel, we talked about the controversial wire x flexible cable, which conductor is the grossest?

Whenever we need to clarify any doubts, we must consult the rules and if you cannot find the answer to your doubt, always remember that the World of Electrical is here and on several digital platforms.