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Re: Extension cords [Re: LongRunner] #219239
04/15/18 11:31 AM
04/15/18 11:31 AM
L
LongRunner  Offline
Member
Joined: May 2015
Posts: 58
Albany, Western Australia
Rather than continuing to debate over what's "statistically acceptable", I really do think we should be questioning the inevitability of wire terminations continuing to fail at all. See my new thread.

Of course, we can never absolutely rule out the occasional freak accident; but I don't see the need to accept such systematic failure as we see...

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Re: Extension cords [Re: C-H] #219240
04/16/18 06:09 AM
04/16/18 06:09 AM
T
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,422
Vienna, Austria
At least in Austria and Germany plenty of rewirable plugs failed back in the old days because manufacturers dipped the ends of the stranded wires in solder before clamping them under a terminal screw. The solder moves under the pressure of the screw and the termination then overheats. I'd say that was clearly the issue in roughly 90% of the failed plugs I've seen. Unless I've forgotten a few I've only ever come across one failed moulded plug and that was on an early-2000s dishwasher and the plug failed in 2016, taking the socket with it. The socket was only three years old, decent-quality and tested after installation so I'd rule that out.

Re: Extension cords [Re: Texas_Ranger] #219241
04/16/18 08:27 AM
04/16/18 08:27 AM
L
LongRunner  Offline
Member
Joined: May 2015
Posts: 58
Albany, Western Australia
Don't forget that there's a very large grey area between a 'comfortable maximum' (IEC 60320 rates that at a pin temperature of 70°C, except for the higher-temperature variants which may reach 120°C or 155°C when further heated by the appliance) and actual meltdown; I've previously run heaters (up to and including 2.4kW @ 240V) through (deliberately long and silly-looking) chains of IEC 60320 C13/C14 cords, to prove the point that it would still work (which it does) wink.
They are mixed 0.75mm^2 and 1.0mm^2, and none of the flexes themselves get warmer than I'm comfortable with. So far, I've only had one pin actually melt the plastic (which I later diagnosed, by autopsy, as a really bad crimp connection that didn't hold onto the wire at all!), but many pins still get too hot to touch (these are mostly "modern" versions, usually from Chinese/Taiwanese manufacturers).

(But then, surely a 10A-rated connector sustaining a heater drawing 10A is just the basic call of duty wink.)

I did have one other defective C13 socket, on a molded cordset made by CMA (back in the 1980s, at a guess). This, however, was a completely different fault: There was a bit of stray PVC in the active/line slot. This cordset ran cool while the connectors were properly seated, but the errant bit of PVC carbonized and created a nasty resistive path (releasing clouds of smoke) when I unseated the C13 end under load. And this one was a bit tragic, really, as the contacts themselves looked much more robust than in newer versions. frown (I salvaged it by cutting off the C13 end and converting it into a short extension cord.)

Apart from such occasional defects, though, the earlier molded cordsets were fantastic (if observed trends continue, they could well provide centuries of reliable service)...
Between the "new" Chinese/Taiwanese versions and decent rewireable connectors, though, I think I'll stick with rewireable (for heavier loads, at least).

Re: Extension cords [Re: C-H] #219242
04/16/18 07:02 PM
04/16/18 07:02 PM
T
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,422
Vienna, Austria
By failed I mean "got hot enough to smoulder and turn a crispy dark brown" or even "hot enough to burn holes around the pins". If you look at a white plug and see a brown circle around one pin you know what's going on. I've hardly ever seen that with stranded wires straight under screws (technically illegal according to German VDE regs) so I'm fairly certain the solder was the issue. It's similar to the troubles with household-size Al wiring in screw terminals.

Rewirable plugs and trailing sockets have pretty much become a DIY item here, everything sold in a store will have a moulded plug on it. Of course electricians do use them for repairs and site-made extension leads too but in Germany the general assumption seems to be that repairs are supposed to be made with OEM parts (i.e. if a moulded plug fails or the flex is damaged near the plug you need to replace it with an entire new flex with moulded plug supplied as a manufacturer spare) and site-made extension leads require all sorts of compliance paperwork and testing so it's safest not to touch anything. At least I see that attitude becoming more and more common in web forums.

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