Hot twist locks

[Cmdr_Suds]

Are you making or breaking the connections under load? Even though they rated to be able to safely do it(you don't want it blowing up in your face), they are not designed to last long if you do. Everytime you pull the plug live, the arc eats away at the contact areas and that adds resistance which in turns makes it get hot. Switches have contact surfaces that are designed to last when making and breaking under load. Plugs and connectors do not.

 

[mxslick]

that would make it worse. under pressure from the terminal the solder will cold flow and result in a loose connection. The instructions on a Leviton twistlock (and these are just as good as hubbell now days) say in bold letters "do not tin conductors".

Good point. I forgot about the cold-flow issue.

That is the point I was trying to make. The connections do not seem to stay tight like they should and when then losen enough they fail. I don't think I have ever taken a flexible cord connection apart that has been in use for any length of time where the terminations did not seem loose to me.

When making up ANY pressure plate style connection, I tighten them up, wait a moment, tighten them again finally check them one more time. They ALWAYS need more tightening when I check them the first time and very rarely the second. Seems as though the wire compresses slowly or something.

then they were not installed properly (i am speaking to hubbell and leviton connectors here). I just disassembled 80 hubbell 5-15 connectors which had been in service for a period of time ranging from 5-10 years. They were installed on 12/3 SO cord, and were used under heavy load (1000w - 2000w) often for long periods of time. out of the 240 wires in terminals, one was loose and it was melted. All the others were still tight.

Willing to bet the loose one was probably never tightened enough in the first place.

Are you making or breaking the connections under load? Even though they rated to be able to safely do it(you don't want it blowing up in your face), they are not designed to last long if you do. Everytime you pull the plug live, the arc eats away at the contact areas and that adds resistance which in turns makes it get hot. Switches have contact surfaces that are designed to last when making and breaking under load. Plugs and connectors do not.

Good point. Just take a look at ANY plug which has interrupted load and see how badly scarred it is!