Twisting conductors or not?

[JohnW2]

Does anyone remember the sockets that had 2 terminals for each pole.

Do you mean one of these....

Untitled

• JohnW2
• 29 Oct 2011
• 6

Apart from this one dusty specimen from my cellar, I haven't seen one for years, and don't know whether anyone still makes them - but they do seem to be quite a good idea. They might even consider providing 3 terminals per pole, in case one has a spur!

Kind Regards, John

 

[Big Tone]

On another point, when I was in the sound installation industry it was quiet amazing how screw terminals miraculously came loose due to vibration at audio frequencies, the same can happen at 50 Hz.

Yes. Eddytone Radio had one, a Faraday Cage, and although for RF isolation was used for other things.

If you have never walked into one I can tell you it's very strange. At molecular level every thing vibrates of course; well if it's above absolute zero...

 

[tew1]

In one make of low cost socket I came across the L and N made good (?) contact under the screw but the smaller CPC could squeeze between the side of the screw and the wall of the circular bore of the terminal resulting in a very poor, zero pressure on the wire, connection. I have seen the same in a consumer unit.
.

this happens more than you think, that's why I like to twist them

 

[tew1]

it doesn't seem right

There's an awful lot which doesn't seem right to you isn't there.

Ever stopped to wonder why that might be?

yes, just because something is considered common or standard practice, doesn't mean it's right, things are constantly changing, reverting, just, some people think and experience, others just do/follow orders.

 

[sparkwright]

In one make of low cost socket I came across the L and N made good (?) contact under the screw but the smaller CPC could squeeze between the side of the screw and the wall of the circular bore of the terminal resulting in a very poor, zero pressure on the wire, connection. I have seen the same in a consumer unit.
.

this happens more than you think, that's why I like to twist them

If the wires are a bit thin for the terminal, you fold the ends over - no need to twist them.

 

[ban-all-sheds]

yes, just because something is considered common or standard practice, doesn't mean it's right, things are constantly changing, reverting, just, some people think and experience, others just do/follow orders.

And some just get a lot of things wrong.

 

[securespark]

I was apprenticed under a spark who trained on the 14th. I virtually learnt all the 14th Ed. at work and the 15th Ed. at college simultaneously. I even have a copy of the 14th!!

AFAIR, it was regulation B60 that got everyone twisting the conductors together:

B60. All terminations of cable conductors and bare conductors be mechanically and electrically sound...

Nowadays, with stranded conductors, we don't do that. But you know how these days when a new Edition of the regs is released there are seminars and courses we can go on with practical suggestions of ways to comply with the changes? Well, I think that whenever that reg. was introduced (it may have preceded the 14th Ed.) it was suggested that the way to comply with B60 was to twist the conductors together.

Even with stranded conductors today, I think it's naff. But with solid conductors, it's downright dangerous, as the solid cores are stressed and can fracture, leaving ring finals and earth continuity open circuit and, as has already been mentioned, it is a PIA to test, inspect and fault-find.

 

[sparkwright]

Before around 1970, when stranded cable was the norm for sockets, EVERYONE twisted them together. I think when solid became the norm, many carried on twisting. I don't think many electricians or non-electricians twist wires, with the possible exception of the earths, as the earth terminals are often on the big side.

Solid twisted wires are a nightmare, especially when, for example, adding a spur - when two twisted solids and one straight solid will not make a good connection.