Is this a copper splice? - Page 1
Forum section: electronics / repair

author: jimmyc_
author_rank: Contributor
timestamp: August 23, 2021, 11:46:47 am
content: Hello chaps!Repair beginner here!I need your help to identify this clamp/splice/swage for a thermal fuse. This looks common but i can only find aluminum ones.Can aluminum ones work in place of the copper ones?What type of crimps should I get?

author: Ian.M
author_rank: Super Contributor
timestamp: August 23, 2021, 12:00:32 pm
content: No, its probably brass. Pure(ish) copper is too soft to make reliable thin crimps from.For a repair job, get any crimps that are rated for a gage of wire that equals the CSA of the wires in your photo + the CSA of the thermal fuse lead, cut off the terminal part (easiest to do if you start with a ring terminal as its flat between the crimp and the ring), and just use the crimp part. For production, look at bare crimp ferrules from a specialist supplier, but you'll probably want a heaver wall thickness than is standard if using them as splices.

author: jimmyc_
author_rank: Contributor
timestamp: August 23, 2021, 06:18:08 pm
content: Cool thanks Ian.M!What does CSA refer to?

author: Ian.M
author_rank: Super Contributor
timestamp: August 23, 2021, 07:01:15 pm
content: Cross Section Area, equal to \$\pi\cdot D^2/4\$ for bare solid wire and approx. \$0.9\cdot\pi\cdot D^2/4\$ for fine stranded wire. For coarse stranded wire, add up the CSAs of the individual strands as one cant assume circular close packing.As you have a US flag, the Wikipedia table of AWG wire sizes may be useful to aid choosing suitable crimps.https://en.wikipedia.org/wiki/American_wire_gauge#Tables_of_AWG_wire_sizesEdit: Sorry, had a brainf--t and gave the formula for circumference, not CSA.Now fixed.

author: jimmyc_
author_rank: Contributor
timestamp: August 23, 2021, 11:13:51 pm
content: Much appreciate your advice!

author: jimmyc_
author_rank: Contributor
timestamp: August 24, 2021, 12:56:09 am
content: Btw, is there a special crimper I have to get, in order to crimp the two wires together?

author: electronicsengineer
author_rank: Newbie
timestamp: August 24, 2021, 06:49:58 am
content: Yes, I need it, something like that...

author: aqibi2000
author_rank: Regular Contributor
timestamp: August 24, 2021, 07:18:21 am
content: Just solder it then heat shrink

author: Alti
author_rank: Frequent Contributor
timestamp: August 24, 2021, 09:36:56 am
content: Quote from: aqibi2000 on August 24, 2021, 07:18:21 amIt is going to be really challenging to solder a 87oC thermal cut-off but with proper technique I think it could be done reliably. However, heat shrinking it reliably is going to require some witchcraft skills.

author: Ian.M
author_rank: Super Contributor
timestamp: August 24, 2021, 10:06:06 am
content: Quote from: aqibi2000 on August 24, 2021, 07:18:21 amGood luck with that! It can be done but to do so so the connection is secure, without blowing the thermal fuse from the heat of the soldering is a royal PITA. Also, mains connections must *NEVER* rely on solder alone, but must always be mechanically secure before the solder is added, so you'd need to form loops in the ends of the thermal fuse leads to hook the mains wire through, which would significantly reduce the lead length available to heatsink it to stop it blowing, and significantly increase the time to fully wet the joint, increasing the odds it blows as you solder it.Quote from: Alti on August 24, 2021, 09:36:56 amYep, I wouldn't tackle it on a bet, without a custom fitted solid copper heatsink to clamp over the fuse body and leads + plumber's freezing spray to chill it right down before hand!Quote from: electronicsengineer on August 24, 2021, 06:49:58 amYep, that will do the job. So will Chinese knockoffs of that brand-name ratchet crimper at a fraction of the price. Don't get the non-ratchet flat plate scissors style tool with wire strippers and bold cutters built-in as it very difficult to get enough pressure to make an electrically and mechanically secure crimp, and its far too common nowadays for them to be made of far too thin mild steel that buckles sideways under load.If you are anyway near a good 'big box' hardware store, see what they've got on their electrical aisle, otherwise trawl thorough this amazon search:https://www.amazon.com/s?k=ratchet+crimping+tool+terminal+kittill you find one that looks like the above, with a terminal kit including ring terminals. I wouldn't trust a crimp ferrule as they are intended to deform slightly for good contact in a screw terminal so have much thinner walls than a regular crimp terminal, and usually less crimping pressure, so avoid those kits for this job. $25-$30 should see you good, with a tool that will last you for years if you look after it.

author: jimmyc_
author_rank: Contributor
timestamp: August 28, 2021, 01:53:40 am
content: Thanks for all your advice, chaps!