Is it ok to splice mains cable ? - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: April 12, 2017, 08:22:04 am
content: HiI have a Dyson vacuum cleaner that needs a new mains cable. I bought a generic one from a store only to find that I need to fit a 5mm male and a 5mm female crimp connector to it. I don't have these and I'm not sure that I could make good connections if I had. So, I was wondering if I could cut off the connectors and a little wire from the old cable and splice them into the new one. The plan would be to strip back a cm of insulation on each end, push the strands from the opposite side into each other, add flux, flow decent solder into them and then cover with a layer of heat shrink.Would this be ok ?Thanks

author: tautech
author_rank: Super Contributor
timestamp: April 12, 2017, 08:34:08 am
content: Yep, on one condition; it need be after the strain relief.

author: Zero999
author_rank: Super Contributor
timestamp: April 12, 2017, 08:49:11 am
content: Quote from: tautech on April 12, 2017, 08:34:08 amYes, don't rely on solder connections for mechanical strength.

author: MrAl
author_rank: Super Contributor
timestamp: April 12, 2017, 10:17:06 am
content: Hi,I had a similar problem with an appliance once. The cord wires broke right at the strain relief.I cut the bad end off, wired it right into the unit internally after taking it apart.If you could get inside the appliance itself you could do the same thing maybe. No more connector to worry about. If you do need a connector, maybe you could add your own, a different kind that can handle the current well.

author: amyk
author_rank: Super Contributor
timestamp: April 12, 2017, 11:41:30 am
content: https://en.wikipedia.org/wiki/Western_Union_splice

author: Monkeh
author_rank: Super Contributor
timestamp: April 12, 2017, 01:24:33 pm
content: Quote from: amyk on April 12, 2017, 11:41:30 amWith stranded wire? In a confined space?

author: Ian.M
author_rank: Super Contributor
timestamp: April 12, 2017, 02:01:26 pm
content: The western union splice is rather awkward in stranded wire. If you flux the wires and lay the ends parallel before applying any solder, then put a tight whipping (seizing) round them with very thin tinned or bright copper wire, you gain nearly as much mechanical strength as the western union splice. A single strand stripped from one of the wires in the dead lead would probably be suitable.Alternatively, go to Maplin, buy the crimps and if you don't have the proper tool and can't be arsed to buy a compound action ratchet crimper, strip the hard blue or red plastic, squeeze the crimp onto the wire with pliers and solder it, with a wet rag round the wire to chill it so the solder doesn't wick up it, and feeding solder into the end of the wire from the terminal end of the crimp. Then you *MUST* heatshrink over the crimp.

author: Vtile
author_rank: Super Contributor
timestamp: April 12, 2017, 02:31:34 pm
content: Quote from: Ian.M on April 12, 2017, 02:01:26 pmAnd then apply yet another heatshrink over the whole repair. Double insulation.

author: Ian.M
author_rank: Super Contributor
timestamp: April 12, 2017, 02:38:24 pm
content: Yes, that too, if the original cable had reinforced insulation at that point. Adhesive lined heatshrink is a good idea as well.

author: Avacee
author_rank: Unknown
timestamp: April 12, 2017, 03:47:49 pm
content: You could get something like this:http://www.ebay.co.uk/itm/Electrical-Joiner-3-Pin-10-A-In-line-Mains-Cable-Connector-White-Plastic-BS5733-/112327064311orhttp://www.ebay.co.uk/itm/13A-InLine-Connector-Box-3-Terminal-Join-Flex-Cable-Wire-Mains-Electrical-Joiner-/222366674125Also available in B&Q and probably Homebase-Bunnings if you want it before the Bank Holiday.http://www.diy.com/departments/bq-black-13a-terminal-line-connector/178106_BQ.prdhttp://www.diy.com/departments/bq-10ah-sp-white-matt-3-pin-inline-connector/753979_BQ.prd

author: David Hess
author_rank: Super Contributor
timestamp: April 12, 2017, 06:39:24 pm
content: Quote from: netdudeuk on April 12, 2017, 08:22:04 amYes, this will work well.The way I do it is to cut the wires so they are offset from each other along the length of the cord so even if there is a compete failure of all of the joints, the exposed wire ends are not adjacent. Then after soldering I use heat shrink tubing on each individual wire and a larger diameter of heat shrink tubing around the whole cord. Of course the heat shrink tubing has to be in place before soldering.

author: Ian.M
author_rank: Super Contributor
timestamp: April 12, 2017, 07:22:30 pm
content: Yes. I had an Antex soldering iron with the cord extended that way for many years. Each wire individually spliced and heatshrunk, with the joints staggered then the insulation built up to the original profile with more heatshrink, short lengths of adhesive lined heatshrink to join the repair to the original installation, then another length of adhesive lined heatshrink extending 3" past the joint over everything. It was a little stiffer when the joint was but stood up to regular use with no signs of distress.I wouldn't recommend doing the same today for exposed wiring- safety standards are a lot tighter and there's always the chance that someone inexperienced will treat the joint roughly and ignore apparently superficial damage to the joint that is actually seriously compromising the integrity of the cable - but it should be fine inside equipment where the user would require tools to gain access.

author: SL4P
author_rank: Super Contributor
timestamp: April 13, 2017, 08:08:00 am
content: Everyone has brought good points to the integrity of the conductors, but also remember the insulation between conductors and to the outside world.The offset joins are also worth implementing where possible.If the lead is under flex conditions pay particular attention at the pressure points.