Proper fastening of wires in an IEC C14 connector - Page 1
Forum section: electronics / repair

author: lpc32
author_rank: Frequent Contributor
timestamp: November 11, 2014, 12:00:41 am
content: I have this C14 connector where the mechanism to fasten the wires to the prongs is just the round screwheads, nothing else.Does this look sufficient? Any suggestions on how to connect it better?

author: TheBay
author_rank: Unknown
timestamp: November 11, 2014, 08:28:01 am
content: That's how all the ones on my UPS look, I just tinned the wire and made it a U shape making sure the insulated part of the wire was on the left hand side.

author: Towger
author_rank: Super Contributor
timestamp: November 11, 2014, 09:01:52 am
content: I bought a couple dozen for a project and ended up with that type. Sure are not all C14 plugs the same, just the price is different.As the 1.5mm 3 core cable I had was much too wide to go around the screws, I resorted to soldering eyelets to the ends. However, I am sure they should have been clamped, to meet wiring regulationsThe next time I bought C14 plugs I happily paid for the expensive Bulgin ones.

author: nfmax
author_rank: Super Contributor
timestamp: November 11, 2014, 09:20:18 am
content: Quote from: TheBay on November 11, 2014, 08:28:01 amNever do that! Never tin stranded wire that will be clamped in a plug or terminal block. The reason why is that solder will plastically deform at a low level of stress (i.e. it will move and not spring back). As the temperature of the contact changes, the tinned wire is alternately squeezed, as the temperature drops, and relaxed as it increases. Each time the solder deforms a tiny bit more and eventually the contact goes high resistance or maybe even open circuit. With mains wiring, this can be a fire risk.I had personal experience with this some years ago, I had an intruder alarm, which was prone to false alarms in the anti-tamper circuit. I couldn't find anything, and eventually resorted to keeping a diary of the events. After a few years, it was clear that the false alarms were most common in March and September. What? Well the diurnal temperature change generally reaches a maximum in spring & autumn (days are still warm but the nights are getting longer & chillier) and the alarm box was exposed to these temperature changes. A few minutes up the ladder revealed the wiring from the anti-tamper microswitch to the alarm box PWA had been - tinned and clamped in terminal block! I soon fixed that one, and no problems since.

author: lpc32
author_rank: Frequent Contributor
timestamp: November 11, 2014, 06:53:59 pm
content: Quote from: Towger on November 11, 2014, 09:01:52 amHow are these constructed?

author: Towger
author_rank: Super Contributor
timestamp: November 11, 2014, 07:03:19 pm
content: I cant find a photo on the internet, but they have proper screw down terminals like choc block etc.

author: lpc32
author_rank: Frequent Contributor
timestamp: November 11, 2014, 10:32:50 pm
content: Any square/flat piece squeezed over the wire by the screw, or just the screw?

author: lpc32
author_rank: Frequent Contributor
timestamp: November 11, 2014, 10:43:57 pm
content: Is that the "standard" method?Too bad good generic crimpers seem too expensive for the very occasional use I have for them.

author: Monkeh
author_rank: Super Contributor
timestamp: November 11, 2014, 10:45:06 pm
content: Quote from: lpc32 on November 11, 2014, 10:43:57 pmIt's the only adequate method I can come up with for these types of connectors. It's a damn tight fit.Option B: Find better ones. Apparently Bulgin ones, as mentioned, have proper terminals.Option C: Mutilate a moulded lead.

author: lpc32
author_rank: Frequent Contributor
timestamp: November 11, 2014, 10:52:54 pm
content: C) In the current case, the solution to how to nicely attach a mutilated cord would end up uglier than stripped-wire-around-a-screw.Any suggestions for cheap but decent all-purpose/type crimpers, of the kind one would find on eBay?