Bad quality copper in LSF singles.

Tuco88

Howdy Folks,

We recently seem to have come across a bad batch of LSF singles.
Have any of ye had issue with copper and especially Lugs recently?

When terminating into sockets with stranded wire, lets say a brown 2.5mm² or 4mm² would you normally twist the stranded into 1 solid like core or just place it right in. I was always taught the first.

Stoner

Wouldn't twist a stranded cable, reduces the CSA and current carrying capacity of the cable.

The Sidewards Man

Stoner wrote: »

Wouldn't twist a stranded cable, reduces the CSA and current carrying capacity of the cable.

Do you pratice bending a cable 180 degree for a termination?

Tuco88

Let's say 2 browns into one terminal. Was just wondering, would you twist them individually into a solid like core for better practice? I know we have to place furrels on stranded wire now but let's say for a socket. If you place it straight in only a section of the stands go under the terminal. Not to sound mad but we have a large site carried out in both ways.

Risteard81

Ferrules are for fine stranded cables (e.g. flex) as opposed to stranded cables.

It is common practice not to twist BS 6491X / BS 6491B singles. But there are two schools of thought on it.

The Sidewards Man

I would be interested to hear Stoners view of a cooker switch termination 6sq with stranded cable untwisted as he advocates.

2011

The Sidewards Man wrote: »

I would be interested to hear Stoners view of a cooker switch termination 6sq with stranded cable untwisted as he advocates.

The picture below shows a "cage type" terminal clamp. Some cooker switches have this type of arrangement. In my opinion it would be best not to twist the cable when terminating to a connection such as this.

Sleeper12

2011 wrote:

The picture below shows a "cage type" terminal clamp. Some cooker switches have this type of arrangement. In my opinion it would be best not to twist the cable when terminating to a connection such as this.

The connection block on the mira elite st shower is just like this. The installation manual states do not twist the cable

Tuco88

What about just screw type terminals like in sockets, if yo do not twist strands tend to go both sides of the screw a source of potential failure. This is an issue that has to do with an ATEX inspection that was also noted.

Any issue with poor quality lugs.

2011

Tuco88 wrote: »

What about just screw type terminals like in sockets, if yo do not twist strands tend to go both sides of the screw a source of potential failure.

My preference when the screw makes contact with the conductor is to use a lug or ferrule if possible.

This is an issue that has to do with an ATEX inspection that was also noted.

Generally in ATEX applications terminals are "increased safety" (Ex e) type.
I always think of this meaning that they are oversized and of higher quality than normal with increased creepage distances. This is to ensure that the connection does not heat which is more important than a Safe Area installation.

What sort of termination are you referring to, power or instrumentation ?

Any issue with poor quality lugs.

Lugs are cheap, only use good ones that fit well.

Risteard81

Leaving aside ATEX for now (it wasn't clear that this was within its remit initially) stranded conductors with a larger cross-sectional should generally be flattened with pliers when connecting into a cage clamp type terminal to prevent them from working loose as the copper settles and causing a high resistance connection.

Tuco88

All power, all the isolators and switchs have furrels. So an issue happened on a socket now all are being looked at ex and non. Looking like the lot will have to have furrels.

2011

Tuco88 wrote: »

All power, all the isolators and switchs have furrels. So an issue happened on a socket now all are being looked at ex and non. Looking like the lot will have to have furrels.

It should be recognised that installing a lug or ferrule on a cable is essentially installing an additional connection (cable to ferrule + ferrule to terminal). This of course can result in increased resistance and the heat generated at this termination point is a function of the resistance. The principle of Ex e is "no arcs, sparks or hot surfaces".

Stoner

Stoner wrote: »

Wouldn't twist a stranded cable, reduces the CSA and current carrying capacity of the cable.

Please explain?