A cable tie (also known as a hose tie, zip tie, or by the brand name Ty-Rap) is a type of fastener, for holding items together, primarily electrical cables or wires. The most common cable tie consists of a flexible nylon tape with an integrated gear rack, and on one end a ratchet within a small open case.
Because of their low cost and ease of use, cable ties are ubiquitous, finding use in a wide range of other applications. And one such strange cable tie use is shown in this picture posted to the Facebook to
This this shows a very questionable way to join two wires. Here instead of reliable join (like proper screw or crimped connector or soldering) was made by just squeezing two bare wires together just zip tie.
This does not look proper or safe way to join cables. But does this work well and how unsafe it this? Has anyone tested what is the current this kind of hack melts away?
The discussion started and quick Google searching did not reveal immediate answer, so I thought I might to do some testing.
There were comments “Tomi Engdahl I was just going to ask the same thing…. if the surface area of contact is roughly the same as the conductor and the zip tie is pulled tight…. it should work? What do you think?” which lead to conclusion that I have to do some testing myself at this point to get this issue sorted out. I started to find this theme interesting.
I did a quick test. I made a test joint with two 0.75 mm2 wires connected with small zip tie.
After several minutes at 5A DC load current no considerable heating compared to cable. I stopped testing because it did not lead to any conclusions.
Maybe I need to test with higher current and maybe longer time to get comparative results?
When I overloaded the same cable setup with 20-28A AC current, things worked some time OK.
Then after minute or so the the wires heated so much that insulating PVC plastic on them seemed to become soft and melting, the zip tie quite quickly melted opening the wire joint with some sparking before any smoke started to come out from wire insulation. So the zip tie failed before the insulation started to melt off.
Finally check some technical data like in “proper engineering method” where you first test and then read the manual last.
The common cable tie is normally made of nylon. One manufacturer says “Ties withstand temperatures to 185°F (85°C) and have a melting point of 495°F (257°C)“. The cable insulation was believed to be made of Polyvinyl chloride (PVC) that has Glass Transition Temperature 82 °C (180 °F) and Melting point 100 °C (212 °F) to 260 °C (500 °F). So the melting point of insulation and the zip ties are around in the same range.
I do not recommend zip ties to use to join cables. They are not designed for that and this type of joints are not safe. I expected the zip ties connection to be a bigger disaster than it turned to be, so it worked somewhat better than I expected, but not well enough to be trusted for any real uses. Keep thing safe use the right job for the task. Use zip ties to only keep the wires and cables together and in the right place. Use proper connectors to connect wires together.