: > I have a small project I put together (this is all inside of a big box : > ... ie: not inside a wall or part of the house ... but I still would : > like to make sure it's safe and meets any code requirements as if it : > was inside a wall or part of the house) which uses stranded copper wire : > (14AWG). I coated the ends with solder and then bend them to shape : > before connecting them to standard outlets (screwed on, not the push : > in). Will this cause any problems or break any electrical codes (I'm : > located in Ontario, Canada in case that matters). : >
: > The reason why I'm asking is because I've been doing a whole bunch of : > reading about issues with aluminum wire, one of the issues being the : > thermal expansion problems caused by the aluminum wire expanding at a : > different rate than the screw connector it's connected to on an : > outlet/switch/etc. So this made me wonder if the solder will cause any : > problems with thermal expansion of it being different than the screw : > that it's screwed on to, etc.? : : You should not solder stranded wire prior to putting it into : a screw terminal. Solder creeps under pressure, so the contact : pressure will steadily reduce over time until it forms a bad : contact. Strands which are tinned during the cable manufacture : are OK, as the solder layer thickness is controlled and very thin. : I'm not familiar with your local regulations, but in cases of : stranded wire connecting to terminations which don't work well : with stranded wire, the normal method is to crimp on a bootlace : ferrule or an eyelet, depending on the terminal style. : : -- : Andrew Gabriel
I know that, at least on Ottawa, and I imagine most places, you cannot tin wires to be used where an electrical inspecation is necessary. Same in the states. No, I cannot cite NEC, so no use asking. The reasons are exactly as Andrew pointed out. Solder compresses and deforms to whatever force is applied to it and as soon as air creeps in, there is corrosion, moisture, etc etc etc., not to mention the affects of vibrations, etc.. How do I know? I got to see a connection that failed, then started to heat (high currents) and the solder dripped out of the connection onto the wireing below it. No, it's not a horror story, but the melted solder wasn't too cute inside the box. Whoever installed it didn't know the first thing about tinning, besides it not being acceptable to do; he had the wiring well "blobbed" with sodler. I think I understand why you want to tin it, but properly dressed stranded wire will work perfectly under appropriate screw heads. If it's a permanent install, I'd modify it accordingly, again along the lines of Andrew's suggestions. He's right on.
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