RCBO blue flying lead

[oddjobber]

I am about to fit some MK RCBOs but I would like some opinions on what to do with the blue flying leads. The type I've got are the 0793* type with the non-curly blue leads. The MK instructions imply that we should put a curl in them but no specifications on how best to do it apart from a small useless sketch. I've seen some fitted elsewhere uncoiled but is there really a benefit and is there a minimum number of curls for safety reasons etc. I assume its to stop electro mag interference(?) but if so, why ain't they pre-curled?!
Does anyone have any in depth knowledge about this?
Thanks chaps.

 

[riveralt]

I am about to fit some MK RCBOs but I would like some opinions on what to do with the blue flying leads. The type I've got are the 0793* type with the non-curly blue leads. The MK instructions imply that we should put a curl in them

That is only because you have read it that way.

but no specifications on how best to do it apart from a small useless sketch.

As above.

I've seen some fitted elsewhere uncoiled but is there really a benefit and is there a minimum number of curls for safety reasons etc. I assume its to stop electro mag interference(?) but if so, why ain't they pre-curled?!
Does anyone have any in depth knowledge about this?
Thanks chaps.

Just fit them as normal - don't worry about the curls.

 

[Taylortwocities]

You just try fitting a 12-way all RCBO board with the curls left in.

Should have taken up hairdressing!

 

[bernardgreen]

Is there any reason why the flying leads cannot be reduced in length provided the cut end is properly terminated with a crimped ferrule to ensure good connection to the neutral bar ?

 

[oddjobber]

Thanks for the tips guys. and thanks to bernard, I was wondering the same thing about the length because they are much too long and I've got a few of them to fit in. I have heard that we are not supposed to cut them but I suspect its bunkum(?)

 

[Taylortwocities]

Bunkum, indeed.

The MK leads are tri-rated cable so (per Bernard) you'll need a crimped ferrule on the cut end (or tin the end with a soldering iron.)

 

[bernardgreen]

(or tin the end with a soldering iron.)

NO please NO

Solder under compression from a screw terminal deforms and the pressure on the conductors reduces to the point where the joint fails.

Cold compression weld of the strands is OK ( as per the manufacturers ) but the compression tool for properly applying ferrules is much cheaper that than a cold weld tool..

 

[studentspark]

I thought people added curls by wrapping around your screwdriver, and it was only for aesthetics. ?

 

[bernardgreen]

I have just spoken to Wylex technical by phone and they say the blue lead can be shortened provided the end is crimped.

( I needed to know for wiring the CUs in the cottage I am renovating )

 

[bernardgreen]

I thought people added curls by wrapping around your screwdriver, and it was only for aesthetics. ?

It does allow for a bit of slack for future repairs to be left tidy in the box but that is about all it does.

 

[oddjobber]

I was told the curls were to stop unwanted electromag induction from tripping the RCBOs but if that's the case why don't we have it on the main RCDs because they are also 30ma. That's why I suspected it was bunkum, also I feel sure MK and others would have to make them with pre-formed curls if that was the case. The answers here so far confirm my thoughts.

 

[oddjobber]

well done Bernard. Thanks for that.

 

[mfarrow]

(or tin the end with a soldering iron.)

NO please NO

Also see 526.8.2.

 

[JohnW2]

(or tin the end with a soldering iron.)

NO please NO

Also see 526.8.2.

As you will know, 526.8.2 (and 526.8.3) actually only relates to 'multiwire, fine wire and very fine wire', but I'm nevertheless sure that Bernard is correct in saying that it's a very undesirable practice for conductors of any size.

Particularly with fine/very fine wires, it's very tempting to tin - but that then invokes the potential problems which Bernard has described.

Kind Regards, John.

 

[mfarrow]

Bernard is correct in saying that it's a very undesirable practice for conductors of any size.

Doesn't 'multiwire' cover all then?