We have a recliner that has electric motors to move it. Before we had it, at some point, the cable had been run over, cut, and repaired. All I can see is electrical tape. The recliner is unplugged. What should I use to fix it properly?
A replacement cable?
Either replace the cable, or use crimps and a couple of layers of heat shrink sleeving (one on the individual wires, and one overall).
John, what's wrong wit things like these?
(other suppliers are available...)
Andy
A new cable from the plug to the termination point inside the chair. After all if you make a fantastic job, you have no way to know if the cable has internal damage elsewhere, where its not visible. If it sits on a carpet, its a fire waiting to happen in my view. Brian
Nothing explicitly (assuming you fit the cable grip properly - unlike in that photo. I would also favour a bit more slack on the earth wire - so that if pulled, it would be the last to disconnect)
They are rather chunky and prone to getting their cables snagged or pulled out though.
For a straight cable repair - rejoining a cut section, they are simple enough.
However they also tend to encourage people to extend the flex, and that can have some non obvious consequences - especially when thin flexes that were already close to the limit for adequate fault protection at their original length are extended.
How about oldering it's sometimes easier depending on what you have to hand. I did this for a laptop lead after a rabbit found it tasty. HP wanted £150 for a replacment. I did U twists on the strands then soldered them, then covered them with heatshrink, then covered the outer with more heat shrink only added a few mills to the overall diameter.
I know crimping is meant to be stronger and longer lasting in theory anyway dependent on whether the rabbit is allowed near the lead. :-)
Possibly not unless you use a decent crimping tool and not one of those cheap combined cutter/stripper/crimp tools often found on Ebay etc.
Thanks everyone. I will upend the thing and see about a complete replacement.
Soldering is ok - although for a flex you can introduce a point of non flexibility. So good support from heatshrink will help.
You would need to extend it by quite a few metres to cause a problem.
<snip>
When I wire plugs (which I've done far more often) I always take care that there is least slack in the live. I want that to disconnect first.
Thanks
Andy
The advantage of soldering is that it's less bulky than crimps so you can end up with a repair that isn't a big lump in the cable. If you crimp it's best if you stagger the crimps to minimise bulk but then you have to strip the outer cover back quite a long way.
I like how across the series of photos:
:-D
This should NOT be your first choice.
Soldering is fine for hobby low voltage/low current DC purposes. Because the materials are not anywhere near their limits.
Any time you repair something, you have to think about strain relief. You want a wrap around the cable, for example, which is stiffer and stronger at one point, and gradually becomes weaker as you get more distant from the repair.
This allows the flexible part of the cable, to take more of the flexing. You do not want the cable bending AT ALL, where the solder part meets the flexible strand part.
If you have no cable wrap at all, consider what you're doing.
Solder XXXXXXXX--------- ---------XXXXXXXX
The solder is as stiff as blazes. The flexible part, where the solder has not flowed into the strands "X" part, is flexible. Where XXX--- meet, that is the failure point. When it snaps (and it will), where the "X" meets the "-" is where it will snap.
This is for things such as a repaired extension cord.
In high current applications (the cable really is carrying
13 amps), the solder point can become warm. It may even become warm enough (some day) to melt the solder. If there is any stress on the cable, perhaps the solder job will pull apart. While there are some recommended methods for splicing flexible stranded sections together before soldering, this is just delaying the obvious.These are not theoretical things. These things really happen. I've had a snapped solder job, right at the stress point.
Using the crimp method, is better. What you want on a crimp device, is a "gas tight" connection. This prevents corrosive gases from attacking the integrity (ohmic nature) of the connection.
Even the device with the screws is better, up to a point. As the thread has already discussed, any time you make a repair, you want the cable to be "not that much thicker", so it does not snag and attract unwanted stress from being yanked on.
One final point. Yes, shrink wrap is nice. Polyolefin tubing. Shrinks to around half its diameter. Must be selected to have some clearance around the work area. (You need a bigger diameter piece than you think. Practice at it.)
The problem with the concept, is the shrink temperature of Polyolefin is higher than the melt temperature of the wire insulation underneath. TEST the insulation by doing a test shrink, by placing just stripped insulation (no wire inside), then shrink some polyolefin around it. Now, take a knife or tool and cut it open. Is the internal insulation melted ? How much damage was there ? Always verify that when applying heat in that way, you are not inadvertently causing a short. Or thinning out some insulation.
You can try applying two layers of shrink. Place one tube of shrink, around each individual wire. Place a second, much larger piece of shrink, around all three wires with their shrink protector. That sandwich may give a bit more protection. Just be careful to verify that all is well, by building a test sample and examining it.
Once the shrink is on, examine the length of material for flex versus distance. If the thing is too stiff, you may want to wrap with an external wrap, to make a flex gradient away from the repair. So it won't "snap" like the soldered case.
I've only ever made one good wrap with electrical tape, on a hand drill repair. I've never been able to make a good wrap a second time :-) There are different kinds of electrical tape. Ordinary stuff and Super33+ . But in the end, they all fail. One just "looks more pretty" than the other. This is why shrink wrap, while having some issues, is a better option. Just verify you haven't gotten carried away with the heat source and cooked the thing.
Paul
Yup... although IMHO, the better option is still to replace the flex if possible
I.E. gripping the outer sleeving of the cable and *not* just the inner conductors as shown in most of the images on that web page.
Yes, definitely. Alternatively if the damage is near one end just shorten the existing cable, often a shorter cable can be handier.
Yes. And professional high voltage high current ac jobs.
not usually necessary or required.
Seldom. It does depend on the application, and a mains splice is not a hazard in this respect. It may well be in other ways though
A soldered join has less resistance per distance than the orifinal flex, so no. Unless of course the repairer is thoroughly incompetent.
No. You'd need to put huge stress on a correctly made joint for that. Try it.
no
solder failures aren't rare. If the joint design is suited to the job, all is well. If you cut corners, not always.
a lot of crimps aren't gas tight. Same story, do it well, no worries, do it badly, problems.
it has its own failure modes. All methods do.
If a flex gets yanked on I'd not repair it, replace it.
sheesh
they do, and should not be relied on. Twisted & taped flex splices are a recipe for trouble in several ways
How hard is it to heat until it shrinks then stop?
Replacing the flex is the sensible option
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