Flex connections

[DeadJoe]

Could someone explain to me the thinking around making connections using multi-stranded flex? There seem to be plenty of options:

Stripping the end of the flex and just tightening a screw onto it (like in a 13A plug).

Putting an uninsulated bootlace ferrule onto the end using a ratchet ferrule crimper, and then tightening the screw onto it.

Putting an insulated crimped pin terminal on the end with a ratchet crimper, and tightening the screw onto the terminal.

Using an insulated cord end ferrule with a ferrule crimper.

Using an insulated blade terminal with a ratchet crimper.

The reason this has come up is because I'm confident that option 1, just sticking the stripped cable into an immersion heater thermostat and tightening the screw is wrong. I've also ruled out tinning the flex end with solder. But then I am left with a few other options, one of which means I just need to get the right sort of crimp to use with my crimper, and the other means buying a ferrule crimper and crimps.

How do you decide what to do?

 

[ColJack]

pins and blades should only be used where you can't physically get the cable into the terminal..

otherwise it's ferrules all the way..

nothing wrong with just sticking the twisted end in either providing it's a terminal designed for that.. not just a screw like in connector block..

 

[wingcoax]

As COL says there is nothing at all wrong with putting a stranded cable into a screw type terminal, most appliances are made for this type of conection and immersion heaters are no exception.

 

[Click-Sure]

Ring crimps?

 

[ColJack]

and how exactly do you intend to get ring crimps into the terminals on a thermostat?

 

[DeadJoe]

That's right - the immersion has a ring connector to earth, another to neutral, then a connection for live to the thermostat which loops on to the cut out and on to the live immersion connector. It's the connections to thermostat and cut-out that were interesting me.

At the other end, the E7 timer instructions have a big notice in them that specifically state that stranded flex is not to be connected to the terminals at the timer. I just wondered what the difference was. Why should it be OK to put a stranded wire in at one end, and not at the other? Is it maybe to ensure there are no stray strands which might cause problems in the future?

But I also wondered what the 'rules' are. How does one make the decision (in the absence of a notice) whether or not to use ferrules? Is amperage a factor?

EDIT: Just spotted this:

nothing wrong with just sticking the twisted end in either providing it's a terminal designed for that.. not just a screw like in connector block..

It looks to me as if the screw acts exactly like the one in a connector block. It just screws into the cavity the bared flex occupies. There is nothing to protect the strands from the screw end.