Coop Posted March 21, 2018 Report Share Posted March 21, 2018 3 hours ago, Tom King said: That looks like a Hubbell to me. It wasn't simply a bad plug, but a bad connection on that plug. It's the same sort of poor connection that caused the issue with the receptacle that drzaius posted, although that receptacle was a poorly designed device to start with because of giving way to fast, and cheap. Proper torque is very important on the screws, as is meticulous preparation of the wire ends. Proper torque, in this case, is only learned by developing a feel for it. Just as fasteners used when assembling an engine, the bolt, or machine screw needs to be stretched a tiny bit to stay in place. That's the plug on the machine, so pretty obviously a half-assed job wherever it was assembled. It looks like one of the conductors burned completely in two, so it's possible there was a wild strand on the hot wire that touched the ground wire. For that type of plug, which I have quite a few of, I always harden the end of the stranded wires with rosin core solder, since having the same sort of trouble after learning the hard way when I first started. I've never had an overheated plug since hardening the ends. What seems like it's tight on stranded wire can come back and bite you later, especially if it's a cord that gets moved around a lot. I hate stranded wires for that very reason. Thanks Tom, from now on, out comes the solder. 1 Quote Link to comment Share on other sites More sharing options...
wdwerker Posted March 21, 2018 Report Share Posted March 21, 2018 Crimp on connectors are a substitute if you don't have a soldering iron handy. Only marginally better than stranded wire under a screw. Solder is better. Quote Link to comment Share on other sites More sharing options...
Popular Post Keggers Posted March 21, 2018 Author Popular Post Report Share Posted March 21, 2018 Oh , one more bit of info that you all might find interesting. The electrician thought that the short duration of the flames might have been the fine layer of sawdust on the outside of the power cable burning. I'd not thought of that until he pointed out the thin layer of sawdust on the rest of the power cable. 3 Quote Link to comment Share on other sites More sharing options...
chashint Posted March 21, 2018 Report Share Posted March 21, 2018 Disagree on the sawdust. Since everything there is non flammable on its own once the metal was melted open the arc stopped so heat source was removed and the fire went out. Quote Link to comment Share on other sites More sharing options...
mat60 Posted March 21, 2018 Report Share Posted March 21, 2018 Not saying sawdust had anything to do with this but I believe its a good idea to blow the dust out of outlets and such. Glad you were in the shop and still have one. Quote Link to comment Share on other sites More sharing options...
Tom King Posted March 21, 2018 Report Share Posted March 21, 2018 I think it just smoked as long as the arc was arcing, and when the gap melted large enough, it just stopped. Sawdust had absolutely no part to play in it. Did the electrician just put stranded wires under the lugs in the new plugs? If so, I guess it was okay since he/she was an electrician. Quote Link to comment Share on other sites More sharing options...
Keggers Posted March 21, 2018 Author Report Share Posted March 21, 2018 54 minutes ago, Tom King said: I think it just smoked as long as the arc was arcing, and when the gap melted large enough, it just stopped. Sawdust had absolutely no part to play in it. Did the electrician just put stranded wires under the lugs in the new plugs? If so, I guess it was okay since he/she was an electrician. There was very little smoke. There were flames. I saw it burning along the cyclone end of the power cord. It burned about 12" of the cord and the flames didn't last for more than a few seconds. The electrician didn't say the sawdust caused the problem - he just thought that what i saw burning might have been the fine sawdust on the outside of the wire. I'm sure he put stranded wires under the lugs. There was no soldering done. Quote Link to comment Share on other sites More sharing options...
Keggers Posted March 21, 2018 Author Report Share Posted March 21, 2018 1 hour ago, mat60 said: Not saying sawdust had anything to do with this but I believe its a good idea to blow the dust out of outlets and such. Glad you were in the shop and still have one. I'm glad I was too. Quote Link to comment Share on other sites More sharing options...
mat60 Posted March 21, 2018 Report Share Posted March 21, 2018 1 hour ago, Keggers said: I'm glad I was too. Your thread got me thinking about how much cleaning and things I should change in my shop when the temps get nice. Good reminder, Thank you. 1 Quote Link to comment Share on other sites More sharing options...
drzaius Posted March 21, 2018 Report Share Posted March 21, 2018 3 hours ago, Tom King said: I think it just smoked as long as the arc was arcing, and when the gap melted large enough, it just stopped. Sawdust had absolutely no part to play in it. Ya, this. Nothing to do with the sawdust. Once I was on a ladder drilling a big hole with a big drill & felt something hot on my chest. There was a jet of blue flame shooting out of the cord at the strain relief. I quickly jumped down & left the drill hanging. The fireworks continued for another few seconds before extinguishing. A post mortem revealed broken strands & burned insulation. I was fine, but had a ruined shirt & blackened undershirt. Thank goodness for clothing! 3 hours ago, Tom King said: Did the electrician just put stranded wires under the lugs in the new plugs? If so, I guess it was okay since he/she was an electrician. I don't usually solder stranded wire before terminating if the terminal is approved for stranded wire. Not needed if things are done right, but I don't think it can hurt. Sometimes it is actually forbidden, such as with some bonding connections (Canadian Electrical Code). Quote Link to comment Share on other sites More sharing options...
bradpotts Posted March 21, 2018 Report Share Posted March 21, 2018 Thanks for posting. This kind of thing is my worst nightmare!Sent from my iPhone using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
Coop Posted March 22, 2018 Report Share Posted March 22, 2018 11 hours ago, chashint said: Disagree on the sawdust. Since everything there is non flammable on its own once the metal was melted open the arc stopped so heat source was removed and the fire went out. I’m not sure I agree. Take a piece of newspaper and roll it up and light it like a torch. Take a handful of flour (non flammable?) and throw it across the torch that you have extended away from your body and face. Damndest flame thrower I’ve ever seen. I’ve used it on several occasions in the country on wasp nest. It’s kind of cool to try, even if you don’t have wasp nest. 1 Quote Link to comment Share on other sites More sharing options...
wdwerker Posted March 22, 2018 Report Share Posted March 22, 2018 Devices that clamp stranded wire instead of just holding it under a screw are much safer. Quote Link to comment Share on other sites More sharing options...
drzaius Posted March 22, 2018 Report Share Posted March 22, 2018 12 hours ago, wdwerker said: Devices that clamp stranded wire instead of just holding it under a screw are much safer. Yes, stranded wire wrapped under a screw does not work well. It needs to be a capture type termination. All good quality cord ends are built with that. Quote Link to comment Share on other sites More sharing options...
Robby W Posted April 27, 2018 Report Share Posted April 27, 2018 Tinning the wires going into a plug is a bad idea and actually against code for anything carrying current. Over time, the solder cold flows and loosens the connection, setting up the conditions for the type of arcing seen here. What probably happened is that the connection wasn't completely tight, allowing the wires to work loose over time. Most Hubbell connectors made in the last 10-15 years have pockets that the wiss are inserted into and the screw tightened, securing the wire and keeping stray strands from touching anything. I have seen people forget to loosen the screw and locking plate , inserting the wire.and then loosening the screw, which seems to hold the wire in place, but causing problems later. Probably not what happened here. I think it was just a case of loosening over time and.the hanging cable pulling the wire out until it arced under load. The flames sound like they were district igniting. Any cable that hangs like that should be checked periodically to make sure everything is kosher. 1 Quote Link to comment Share on other sites More sharing options...
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