doubling cable over for termination?

[MerlinGremlin]

Working onsite with a few apprentices the other day and noticed that every cable they terminated into the mcb or rcbo was doubled over, so when I asked them why they were doing it there reply was college taught them to do it that way. Now I have always terminated the cable without doubling it over, so am I wrong or the college lecturer????

 

[J.C.E]

people do it because then there is more of the conductor gripped by the terminations- most people only do it with 1mm upto 2.5mm- any bigger then it gets a bit more messy/tricky

 

[GMES]

This is not a new thing Guys who have been in the game 50 years do it, I think it is a good practice jmo though.

 

[Richard Burns]

I too was taught to double over and "fill the hole with copper", the intent being that if the terminal is designed for a larger csa cable then the terminal screw will still bite on the cable and not pass the cable down the side of the screw and cause a looser connection that may fail.
I think this is the current thinking and seems to be generally approved of.

I do not agree and think that careful termination should avoid this problem and if you get the terminal biting only on the loose end that is connected by a heavily folded strand to the conductor in use this may not be good. Also the number of doubled over ends I have to cut off when adding cables to a terminal is annoying.

However this is not the approved wisdom, so I just carry on my merry way.

 

[MerlinGremlin]

I've never done it as I was told it was doubling your csa, how does this affect using torque setting screwdriver? Also if you look on mcb ' s or rcbo's it shows the cable as normal not doubled over.

 

[J.C.E]

did you believe it was double your csa?

 

[Richard Burns]

Generally MCBs etc have cage clamp terminals and so should be able to tighten accurately on any cable, though having a single conductor at the edge of the terminal may cause strain on the mobile plate as it will clamp at an angle. This is less likely with a doubled conductor.
Obviously this has no effect on csa as the csa terminated is immaterial to the conductor csa that is carrying the current.
Torque screwdrivers will still tighten to the same torque irrespective of the content of the terminal, you could ask the same question for when you terminate two cables in an MCB, or more.

 

[Dave OCD]

I always double over on 1mm,1.5 & 2.5 when there is only a single conductor being terminated. On sockets where there are 2 x 2.5mm T&Es I'll double the sleeved CPCs, I just think this method gives a better connection in general.

 

[ipf]

I used to double years ago but very rarely do these days and I can't remember ever being called back to a job for a broken cable or bad connection. Most terminals are perfectly capable of taking a single core adequately. I suppose it's case of how you feel but situations occur where removal of cables, particularly in future testing circumstances, can cause problems and over exertion to the cable and terminals.
I also find many 'rushed' jobs where doubled cables connections involve the insulation being captured by screws.

 

[7029 dave]

Solid core always double over.

 

[PEG]

For myself,doubling up would depend on circumstance...some cage clamps are,or end up,with a curve,and therefore make a better termination,with the single conductor being centered. Doubling up makes this easier to achieve.

We all have our "quaint foibles",and i suppose this does not matter,providing the end result is a reliable,tidy termination.

For many years now,i have never fitted a plug top,without end-sleeving the conductors,and having a tad of slack cable on the earth pin...

I have several Mustad fly-fishing mini boxes,filled with the variety of ferrules required,spread about my kit...

Extravagant...unnecessary...OCD ? ....you decide...:ihih:

 

[sparkstu]

I was taught to double up on mcb's / rcbo's on 1.5 and 2.5 and still to this day do it also double over earths at sockets

 

[Andy78]

I too was taught to double over and "fill the hole with copper", the intent being that if the terminal is designed for a larger csa cable then the terminal screw will still bite on the cable and not pass the cable down the side of the screw and cause a looser connection that may fail.
I think this is the current thinking and seems to be generally approved of.

I do not agree and think that careful termination should avoid this problem and if you get the terminal biting only on the loose end that is connected by a heavily folded strand to the conductor in use this may not be good. Also the number of doubled over ends I have to cut off when adding cables to a terminal is annoying.

However this is not the approved wisdom, so I just carry on my merry way.

Yep this is the reason for teaching apprentices to double over. If you double over a cable it can't happen, but there is the chance of it happening with a single solid conductor.
I think this practice is even more relevant nowadays with the reduced practical training in some sectors of the industry and poorly manufactured screw terminals in some equipment.

 

[D00DY_T00DY]

Working onsite with a few apprentices the other day and noticed that every cable they terminated into the mcb or rcbo was doubled over, so when I asked them why they were doing it there reply was college taught them to do it that way. Now I have always terminated the cable without doubling it over, so am I wrong or the college lecturer????

Personally, I've been taught any termination that is having one cable that can fit two the end should be doubled over.

 

[nickblake]

I double over the cable on 1.5 and 2.5mm reason with the crap screws on consumer units and accessories they trend to dig into the copper and causes a weak spot , when the cable is doubled over then the surface area making contact on the connections is doubled thus reducing the risk of the cable being weakend , on MCB's it does tend to get a better connection bent over as at that point the connection area is doubled, just my opinion.