How tight is too tight

[pna]

I've been replacing various sockets and switches in the house we moved into earlier this year and have been surprised to find that almost without exception, the screws to connect to the electrical cables had been done up so tightly so as to create a real dent in the wires, in some cases close to severing it.

Am I right to assume this was too tight? (In cases where it looked as thought the wire might break off, I trimmed them before reconnecting).

 

[IanDB]

create a real dent in the wires

Tight enough.

close to severing it

Too tight.

Copper is malleable and in order to get a good LONG LASTING contact needs to be under compression at all times. Screwing down onto the wire and deforming it to take up the shape of the receptacle is the best way to guarantee a good joint. If you don't tighten it up sufficiently, over time the effects of miniscule amounts of heating and cooling and associated expansion and contraction will cause the joint to weaken and the cable will become loose.

 

[securespark]

Create a better termination where only one wire enters the terminal by doubling over the bare conductor and flattening with pliers before terminating. The screw has more to bite on.

 

[pna]

Thanks to both.

 

[securespark]

Alternative answer:

Too tight is painful!

 

[ban-all-sheds]

For whom?

 

[mildmanneredjanitor]

His wife... Linky