Ferrules into MCB/RCBO

[vwes59]

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How do you deal with stranded single cable into a MCB/RCBO ? Would you ever ferrule stranded 1.5 or 2.5 singles into a MCB/RCBO ? I can't see a reason why not except for the length of the ferrule pin, although i believe you can get different lengths. I dont believe there is anything in the regs concerning the use of ferrules.

 

[telectrix]

How do you deal with stranded single cable into a MCB/RCBO ? Would you ever ferrule stranded 1.5 or 2.5 singles into a MCB/RCBO ? I can't see a reason why not except for the length of the ferrule pin, although i believe you can get different lengths. I dont believe there is anything in the regs concerning the use of ferrules.

you don't use ferrules on 7 strand cables. ferrules are for fine stranded cables like flex.

 

[DefyG]

Most mcb's/rcbo's do not have straight screw connections (Usually a little plate to clamp conductors so not necessary but may be necessary on the neutral and earth bars where usually a straight screw connection (there is a reg but do not recall it off hand).

 

[telectrix]

i use ferrules on the RCBO N cables if I have shortened them ( which is usually the case) as they are fine stranded.

 

[Lucien Nunes]

There is no need to ferrule a class 2 stranded conductor in a rising clamp screw terminal such as on an MCB. The terminal is designed for this application and will not damage the cable, nor can any strands escape.

Many terminals of this type are suitable for class 5 and 6 fine-stranded cables without ferrules too. E.g. see this description of Weidmueller DIN rail terminals:

Weidmuller W-Series Terminal Block Selection - Specialty Control Systems

Thousands of Weidmuller Terminal Blocks In Stock at Specialty Control Systems. Largest Selection Online.

www.specialtycontrolsystems.com

The ABB motor starter I installed last week is factory-wired with fine-stranded cables; only the small control wiring has ferrules, all the power cables 2.5mmsq and up are inserted directly into the contactor and isolator terminals without ferrules

Although a ferrule is neat, prevents stray strands and protects the cable around the insulation shoulder, there is an argument against using them unless necessary, as they add an extra layer of contact interface (cable>ferrule, ferrule>terminal). That is the lesser consideration where the ferrule is adding security of clamping and protection of fine strands e.g. in basic screw terminal busbars.

 

[Doomed]

How do you deal with stranded single cable into a MCB/RCBO ? Would you ever ferrule stranded 1.5 or 2.5 singles into a MCB/RCBO ? I can't see a reason why not except for the length of the ferrule pin, although i believe you can get different lengths. I dont believe there is anything in the regs concerning the use of ferrules.

526.9

Don't actually mention ferrules but implies thier use with fine wire multi strand cables

 

[vwes59]

Ok, thanks. Interesting to get people's views on that. Yes I notice a lot of sparkies using them on the RCBO neutrals once they've been shortened. I use them a lot inside CU's on the screw terminals, just wondered what the views were on using them within the MCB's etc.

 

[Mike Johnson]

IMO once the ferrel has been inserted into the terminal and crushed the ferrel becomes irrelevant, but important in a screw terminal if the cable is multi strand, so its according to what the cable type is.

 

[Dustydazzler]

I have been a bit slow to jump on the ferrel bandwagon, I usually just fold over the ends and to make a connection

But have bitten the bullet and ordered a ferrel bootlace crimper and box of ferrels off amazon , like Tel says mainly just to make neat end off if and when I need to cut an RCBO flying lead a bit shorter for neatness , that said I was taught not to cut the flying leads in case the next bloke wants to move the RCBOs about but in this day and age of Instagram picture perfect boards all the cables appear dressed within an inch of their life