Bootlace ferriles

[Sparkattack]

Came acroos this today during an inspection of a 3 phase square D load centre. The cable was a temporary supply to some contractors cabins onsite, 32 amp MCB which was terminated with a bootlace ferrile. I know bootlace ferriles are widely used in control wiring, im just interested in peoples opinions on there use for this application??

 

[cook1e]

surely you would only get minimal surface contact with the bootlace ferrules

 

[benji]

probably same contact area as a pin crimp ,the question is was it fitted/crimped correctly and was it overloaded

 

[Deleted member 26818]

No, I would not use a bootlace ferrule for this application.
As cook1e has pointed out, you would achieve a greater contact area for the conductor in the terminal if a ferrule was not used.
Appart from the obvious problem that can occur if the ferrule is not installed correctly, as evidenced in your photos.

 

[telectrix]

bootlace ferrules should only be used on flex or other multi stranded cable. ( i don't mean 7 strand ).

 

[Engineer54]

Haha, ....I've got news for all you disbelievers, ALL final circuit conductors on every prestige project i've ever been on, or seen have been connected using crimped flat Pin connectors!! Literary thousands upon thousands of them all the way up to 16/25mm.... after that, crimped lugs!! All or the vast majority of the final circuit conductors are multi stranded, similar to what you find in SWA cable conductors. The correct crimp connector is those with a flattened end connection. Even normal ferrules where the conductor passes through the connection area can be relied on, using a good crimping tool....

Damage as seen in the OP photos, is far more likely to have been caused by either a bad crimp, or loose terminal connection, and probably the latter, End Of!! I don't know how many times i have to say this, but crimped connections made with ''Good'' quality crimps, and a ''Good'' crimping tool that deforms the conductor(s) within the crimp can't be beaten!!

 

[mogga]

Im with E 45 there probably down to combination of Slack conection or as is more probable overloading as temp cabins pile heaters in and use as drying room it theres a socket it NEEDS to have a heater plugged in

 

[johnboy6083]

im with them too. our company makes us crimp everything with bootlace ferrules, or other suitable crimp. I work on sytems that are 20 years old, and not seen a problem with a crimped connection. as others have stated, more likely loose connection, long duration overload or failure of the MCB

 

[Marvo]

Haha, ....I've got news for all you disbelievers, ALL final circuit conductors on every prestige project i've ever been on, or seen have been connected using crimped flat Pin connectors!! Literary thousands upon thousands of them all the way up to 16/25mm....

I've been following this thread with interest. I've never seen any regulations that suggest it's a good idea to use bootlace ferrules on final power circuits that are run in FT+e or housewire.I'm not suggesting that such regs don't exist, I've just never seen any.

We always use bootlace furrules for multi-stranded wire such as flex or panel wire. To me this makes perfect sense to prevent stray strands going their own way and to possible better distribute any stress or strain on the wire at the point of termination.

Obviously with wire over 16mm or 25mm a crimped lug is the standard.

The thing that makes me not buy into using bootlace ferrules on final circuit or general power wiring is that there's often multiple wires going in one termination. I'm not sure if there was three wires in a single terminal that they would sit so well together and that the clamp tension on each would be equal.

I'd be interested if anyone knows of some peer reviewed study data on their use in this application, particularly MTBF and strain tests etc.

 

[johnboy6083]

You have double bootlaces crimps for this situation marvo. Both cables go into the same ferrule and they are crimped together. I much prefer 'spade crimps' though (red/blue/yellow variety)

 

[Engineer54]

I've been following this thread with interest. I've never seen any regulations that suggest it's a good idea to use bootlace ferrules on final power circuits that are run in FT+e or housewire.I'm not suggesting that such regs don't exist, I've just never seen any.

We always use bootlace furrules for multi-stranded wire such as flex or panel wire. To me this makes perfect sense to prevent stray strands going their own way and to possible better distribute any stress or strain on the wire at the point of termination.

Obviously with wire over 16mm or 25mm a crimped lug is the standard.

The thing that makes me not buy into using bootlace ferrules on final circuit or general power wiring is that there's often multiple wires going in one termination. I'm not sure if there was three wires in a single terminal that they would sit so well together and that the clamp tension on each would be equal.

I'd be interested if anyone knows of some peer reviewed study data on their use in this application, particularly MTBF and strain tests etc.

For argument's sake lets take a FRC where 2 conductors need to be terminated into a protective device. Using the next size up or a suitable sized crimp both conductors are incorporated into the same crimp. The very nature of the way a crimping tool forces the crimp onto / into the conductors, ensures compression of crimp to conductors.

On ferrule type crimps, with say three conductors (which is rarely seen, due to contract specifications) the ferrule is first deformed/wrapped around the conductors taking up surplus crimp material, then compressed onto the conductors deforming the conductors within the crimp in the final process.

Try it yourself with some off cuts and a suitably sized ferrule crimp for the overall conductor size. I defy you to be able to pull those conductors out of a well made crimp, it'll be like a solid mass of conductors and crimp material. A far better terminal connection than having 3 separate conductors, being inserted into a protective device, and far less likely of not securing equal terminal clamp tension!!...

 

[Deleted member 26818]

Ok, I see that a couple of people disagree with me.
That's fine, everybodies entitled to their opinion.
However, no one appears to have put forward an explanation as to why, they would consider using a bootlace ferrule?
My reasons for not using them are these:
Purchasing a crimper is very expensive.
Applying the ferrule is time consuming.
Using a ferrule can make withdrawing the conductor difficult, because of the manner the ferrule deforms.
The ferrule prevents the conductor strands from spreading, and in many cases this reduces conductivity.
Using pin crimps means even less contact area, as the pin is usually of a harder material than even solid conductors.
I would not use a dual entry ferrule, as such would hinder testing, in much the same way as twisting together CPCs and using a single piece of sleeving makes life difficult with T&E.
Judging from the photos, it would appear that the ferrule has not been applied correctly, however it could be that the ferrule has been applied correctly, but due to poor conductivity the joint has overheated?

 

[johnboy6083]

I agree with some of your points spin. Crimpers are expensive, my self adjusting one cost me £113. I also agree that using double bootlaces ferrules is a pain when it comes to testing or fault finding. That's when I prefer to use spades.

I don't agree with the conductor deforming argument. I see far more deformation from twisting normal stranded cable. I do agree that there is no need to crimp these cables, but i don't see a detrimental effect of doing it. Also I disagree with the poor conductivity argument. You get no less surface area contact on a ferrule, than you would on a solid core.

 

[Sparkattack]

On further investigation iv found out that it was supplying a single cabin office and dont believe the circuit was overloaded but whose to say what they have plugged into it? I personally believe it was a bad connection, looking at it closer i think it had been clamped half on the plastic cover of the ferrile creating a poor connection. Its interesting to see other peoples views on this, i personally wouldnt use them for terminating final circuits such as this due to the size of terminal being connected into compared to the size of the ferrile being used, theres more chance of catching half of the insulation of the ferrile in the connection. Id prefer to use them in control wiring such as using the din rail mounted connectors that are sized so that only the metal part of the ferrile can be physically pushed into the terminal. The main reason im asking for peoples opinions on this is because my company specify to contractors installing or working on our electrical systems that they use a crimped connection or ferrile connection. Thanks for your views.

 

[johnboy6083]

im currently working for a water company also, and they specify to us (a main contactor) that we have to use crimped or ferruled connections.
To be honest though, this could of just as easily happened with no ferrule, ie pinched onto the insulation.

 

[Sparkattack]

Yeah how did you guess, this must be a common requirement in the industry! Youve got a point its only as good as the person installing it i suppose!

 

[Marvo]

For general house circuit or RFC wiring it seems to be a swings and roundabouts thing to me.

On the pro side it may result in a mechanically stronger connection and a lower resistance connection but I've scoured the net for conclusive data from studies of this and I can't find any.

On the con side it's time consuming, it needs probably more than one good quality crimper tools, a range of several sizes and combinations of ferrules and it makes for difficult splitting up of a circuit for future testing.

If you add that to the lack of any requirements for this procedure in the existing (or previous versions) of any regulations I've ever seen, I won't be adopting the method as standard practice at least for now.

If I can see some real evidence of the benefits of using this method and the need for those benefits then I would happily review.

 

[johnboy6083]

i wouldnt use this method for anything other than flex connections, and process systems , ie pumps/machines ect, and the control sytems for these.

for normal building services, i dont bother, as the terminals on most of the gear is tight as it is, never mind adding bootlace ferrules.

 

[johnboy6083]

Yeah how did you guess, this must be a common requirement in the industry! Youve got a point its only as good as the person installing it i suppose!

your profile mate.

 

[Engineer54]

I agree with some of your points spin. Crimpers are expensive, my self adjusting one cost me £113. I also agree that using double bootlaces ferrules is a pain when it comes to testing or fault finding. That's when I prefer to use spades.

I don't agree with the conductor deforming argument. I see far more deformation from twisting normal stranded cable. I do agree that there is no need to crimp these cables, but i don't see a detrimental effect of doing it. Also I disagree with the poor conductivity argument. You get no less surface area contact on a ferrule, than you would on a solid core.

Deforming of the conductor within the terminal crimp, is the main point of a good crimping tool, especially the non insulated crimps. Apart from anything else, it secures the crimp to the conductor.

No-ones saying that crimped terminals should always be used, but on all of the high standard prestige projects, you will normally find that the contract specifications will most certainly call for there use on all final circuit distribution boards and panels etc!!

As for contact area, that very much depends on the type of crimp connector, or ferrule your using, along with the shape of the crimping tool dye. With the flat pin crimps you will certainly have far more contact area than that of a solid core conductor.

 

[vaughant]

As E54 says their near enough standard in industry,particularly in the control side of things.
A good crimp tool helps but I'm personally not a fan of any of these ferrule things on anything above 10mm cable,I've seen a few burnouts recently on IR heater plugs and each time the cause has been these things,quite possibly not connected right in the first place but IMO every termination or join in cable is just another place where a fault could occurr(that's the control spark in me coming out).
I cured the heater problem by squashing the ends in the terminal post and tinning the ends with solder and I've had no failiures since.
Obviously this is even more bloody time consuming!!!

 

[Adam W]

Marine wiring uses stranded cable to allow for vibration, so all terminations are made either with a ferrule or in clamp type terminals or wagos, but never a screw termination such as in a plugtop.

Bearing in mind the way a ferrule works (a terminal screw clamps down onto it) I don't see that a ratchet crimper would be strictly necessary; you can pick up a pair of non ratchet 'plier type' crimpers for around 12 quid.

IMO reg 526.8 requires multiwire, fine wire and very fine wire conductors to be ferruled when used with a screw terminal, as I've mentioned in other threads.

IMO there is no point using ferrules with T&E.

 

[Engineer54]

Marine wiring uses stranded cable to allow for vibration, so all terminations are made either with a ferrule or in clamp type terminals or wagos, but never a screw termination such as in a plugtop.

Bearing in mind the way a ferrule works (a terminal screw clamps down onto it) I don't see that a ratchet crimper would be strictly necessary; you can pick up a pair of non ratchet 'plier type' crimpers for around 12 quid.

IMO reg 526.8 requires multiwire, fine wire and very fine wire conductors to be ferruled when used with a screw terminal, as I've mentioned in other threads.

IMO there is no point using ferrules with T&E.

I would have to disagree with you on that one, To obtain a rock solid connection between ferrule and cable you need a ratchet crimping tool every time. To be honest, i wouldn't give a thank you for a non ratchet crimping tool, not unless your built like king kong!! lol!!

Agree with you on the T&E though, ferrules on the whole are pretty useless on solid conductors... They would require a standard flat style crimp terminal...

 

[vaughant]

Yeah the ratchet crimpers are ACE!!!
on thin cable you could probably get away with a good strong grip on the ferrule but it's just as easy with the ratchet.
Never seen them on t&e personally,pretty pointless really as it's just single core,no chances of strands hanging off.

 

[Deleted member 26818]

Reg. 526.8 as far as I'm aware requires the conductor to be protected.
This can be achieved, simply by twisting and folding over the conductor.