Quote Originally Posted by FEM2008 View Post
BY the way, if anyone is looking for the NASA link on workmanship, here it is:
https://nepp.nasa.gov/files/27631/NSTD87394A.pdf
Soldered splices start at page 68.

Other standards can be found here: https://nepp.nasa.gov/index.cfm/5511
I believe Jon posted a link to NASA standards in one file a while back. HERE IS ONE:https://archive.org/details/nasa-wor...ge/n3/mode/2up


What I meant regarding low voltage and low current are battery powered type projects, such as an Arduino circuit. Mains circuits have the capacity to supply hundreds, even thousands of amps very quickly during a short circuit. That's why circuit breakers are rated for 10,000A short circuit capacity for home panels and much higher for industrial applications and building distribution panels. Also, conductors experience tremendous forces during a short-circuits due to generated magnetic forces and capable of whipping cables around, hence the requirements for fastening cables at regular intervals and at junction boxes. Solder is much less conductive than copper (by a factor of ~10 if I recall correctly) and in an event of an overload, the temperature of the solder will rise very quickly and can melt. By the way, eutectic solder is used in thermal circuit breaker and melts during an overload, which then allows a ratchet mechanism to rotate and trip the breaker.

I am not saying that your method will result in a the wires separating, but I would not trust it from burning down my house.
What is applicable here is not NASA, but NEC code. I am not sure that NEC code allows electrical splices outside of a junction box or without an approved splice device that completely encloses the splice and mechanically secures the cables. There are products like these below that can be used for solid wire in certain situations (such as fished wire in existing building): https://www.homedepot.com/p/NSi-Indu...MS-3/307358485. Perhaps some electricians can shed some light on the NEC code requirements. I worked with industrial equipment twisting wire and soldering to splice is a no no.

While the western union splice is accepted by NASA, it is used with solid wires. Twisted soldered stranded wires fail quicker than untwisted wires. If you dig in the NASA case files and others, you'll find examples.

By the way, I love your posts and ideas you publish and always learn something new.

You really got me thinking about this. After a few false starts, I came up with this argument. If I'm "blowing smoke", please let me know. All of us are smarter than any one of us:

The worst case scenario would be a fault in the extension cord that is just below the breaker's trip current. A UL approved cord must not cause a fire. My guess is that the heat from the conductors will cause the plastic to melt and cause the conductors to short. This would greatly increase the current and the breaker should trip. In thinking about the heat needed to melt plastic versus the heat needed to melt solder, I expect that the splice will remain sound during this fault.



As to burning a house down, I recently almost had a front row seat. My neighbor came over and asked me to check out a problem. In the kitchen was a blackened outlet pulled about 6 inches from the wall. All of the plastic around one of the screws was gone. All that was left was the screw and the conductor. A few MONTHS before, she had heard crackling so turned off power and pulled the outlet out. Then she reapplied power because it was essential to the lives of some very expensive tropical fish. Eventually the crackling got worse and she could see a tiny but bright light in this area. The insulation on the attached wire fell off. Hmmm. Maybe something is amiss...

After removing power and letting it all cool, I gently moved the wire. It was only attached to the screw because it was formed around it. I think the installer forgot to tighten the screw in the first place. That was over 15 years ago.

I was able to cut off the damaged wire and replace the outlet. I then checked that the current being drawn through this wire was safely below the breaker's trip current. I left after suggesting to her that she hire an electrician to check that all screws are tight so this doesn't happen again.

Rick