Extending an electrical lighting cable in porch

[JohnD]

how does the heat shrink not shrink with the heat of the soldering,

when I do it, by being slid into place afterwards. I do not try to solder the sleeve.

 

[plugwash]

You want a hot and powerful enough iron that you can complete the joint quickly and thus minimize heating of the cable..

For a joint that size I would certainly want more length than is shown in that photo. I've certainly had times when I had to re-do a joint because I accidentally shrunk the heatshrink while soldering the joint.

 

[bernardgreen]

by being slid into place afterwards.

The first conductor can be soldered and the sleeve, out of the way on the cable sheath can then slid onto and shrunk around that conductor.

How do you get the sleeve onto the second conductor ?

 

[Harry Bloomfield]

How does the heat shrink not shrink with the heat of the soldering,

Is that photo intended as a serious way to make a soldered inline joint?

That is a very poor way to do it. I always firmly twist them then solder. To improve flexibility of the joint, it can just be soldered at the ends, no solder in the centre.

 

[bernardgreen]

Is that photo intended as a serious way to make a soldered inline joint?

Yes. Mechanical "strength" is provided by the way the copper is hooked together and the "connectivity" of the joint is provided by the solder.

To improve flexibility of the joint

My opinion is any joint should be protected from being flexed

 

[Harry Bloomfield]

Yes. Mechanical "strength" is provided by the way the copper is hooked together and the "connectivity" of the joint is provided by the solder.

Sorry, we will have to disagree on that particular joint, the mechanical strength is quite limited, when compared to a well twisted and soldered.

My opinion is any joint should be protected from being flexed

Of course, but sometimes some flexing cannot be avoided. Too rigid a joint and it can be its own worst enemy.

 

[bernardgreen]

Of course, but sometimes some flexing cannot be avoided.

In which case the cable should not be repaired but instead it should be replaced.

 

[aptsys]

Sorry, we will have to disagree on that particular joint, the mechanical strength is quite limited, when compared to a well twisted and soldered.

The joint should be mechanically sound before any solder is applied - that is when you tug at the two conductors, it should not separate.

 

[Harry Bloomfield]

The joint should be mechanically sound before any solder is applied - that is when you tug at the two conductors, it should not separate.

That was what I was always taught, but I would not expect Bernard's simply hook joint to survive a slight tug.

 

[aptsys]

I would have assumed it would be twisted after the hook, but who knows.

 

[bernardgreen]

but I would not expect Bernard's simply hook joint to survive a slight tug.

I would have assumed it would be twisted after the hook, but who knows.

I "stole" the image, yes.. I do twist the strands to make eyelets out of the hooks.

 

[Harry Bloomfield]

I "stole" the image, yes.. I do twist the strands to make eyelets out of the hooks.

Even so, it relies on a small point of contact and a lot of solder to make a joint. A good joint needs little more than 'tinning' to stabilise it.

 

[plugwash]

The first conductor can be soldered and the sleeve, out of the way on the cable sheath can then slid onto and shrunk around that conductor.

You have to strip enough sheath that you can put the sleeving for the individual conductors on an individual conductor without accidentally shrinking it during soldering.

This is obviously a balancing act because on the one hand you don't want to make the joint longer than nessacery but on the other hand accidentally shrinking the sleeve can be a PITA.