New Consumer Unit

[flameport]

If they weren't so expensive I might be willing to splash out, but they're still silly money

Not worth bothering with.

I have used one, a couple of years ago when the ELECSA inspector person visited.
Every screw in the consumer unit it was tried on was already tight enough - all of the screws having previously been done with a normal screwdriver.
On using it to do up a terminal, it clicked at what seemed ridiculously loose, the wire was not securely held, and the screw could be done up another full turn using a normal screwdriver.

If people are actually using these things for CU terminals, no wonder there is the increase in overheating and fires.

 

[securespark]

Are the Modulo drivers any good?

My ex-colleagues say that some have broken, another reckons you should use both sizes to avoid breakage.

Are CK the only manufacturers of these?

Never got to use one before I retired...

 

[JohnW2]

On using it to do up a terminal, it clicked at what seemed ridiculously loose, the wire was not securely held, and the screw could be done up another full turn using a normal screwdriver.

Very similar to my experiences which I described. I would never trust them - or, rather, the MCB/RCD etc. manufacturer's recommended torques.

With the one I had (still have, somewhere, I guess - although it's never used!), I determined by experiment that it seemed that when screws were done up 'satisfactorily' (by my usual 'judgement') with a normal screwdriver, the torque involved was usually around 50% greater than suggested by the manufacturers.

Kind Regards, John

 

[ban-all-sheds]

On using it to do up a terminal, it clicked at what seemed ridiculously loose, the wire was not securely held, and the screw could be done up another full turn using a normal screwdriver.

If people are actually using these things for CU terminals, no wonder there is the increase in overheating and fires.

Is nobody prepared to consider that the recommended torque settings might have been properly determined, and are actually the right ones to use? And that maybe doing things up "good and tight" risks distorting the terminal, damaging the thread, damaging the conductors?

Remember we are talking here about major manufacturers, with decades of experience - why would they either just make figures up, or carry out flawed experiments to find what the torque should be?

 

[JohnW2]

Is nobody prepared to consider that the recommended torque settings might have been properly determined, and are actually the right ones to use? And that maybe doing things up "good and tight" risks distorting the terminal, damaging the thread, damaging the conductors? Remember we are talking here about major manufacturers, with decades of experience - why would they either just make figures up, or carry out flawed experiments to find what the torque should be?

I've certainly considered that a lot, and it was a cause of concern to me when I first discovered how much difference there was between what had been (and remains) 'my usual practice' (for decades) and what happened when one used the manufacturers' recommended tightening torques.

However, just as with flameport's experiences, in many cases use of the manufacturer's recommended torque left me with a situation in which the conductor was clearly 'loose', and quite probably could have been pulled out - and I find it hard to believe that such a situation represents a satisfactory electrical connection (or an electrical connection that would remain satisfactory). How that arises when the recommendations come from "major manufacturers, with decades of experience", I haven't got a clue - I can but report my experiences.

You've only so far heard of the experiences of flameport and myself - do any others have any experiences to report?

Kind Regards, John

 

[davelx]

However, just as with flameport's experiences, in many cases use of the manufacturer's recommended torque left me with a situation in which the conductor was clearly 'loose', and quite probably could have been pulled out - and I find it hard to believe that such a situation represents a satisfactory electrical connection (or an electrical connection that would remain satisfactory). How that arises when the recommendations come from "major manufacturers, with decades of experience", I haven't got a clue - I can but report my experiences.

You've only so far heard of the experiences of flameport and myself - do any others have any experiences to report?

Kind Regards, John

There are so many combinations and variables here - the number of conductors to be connected, their construction (solid/stranded), sizes and positions relative to each other and to the screw terminal - that I cannot see how a manufacturer can give any figure at all, without specifying the exact conditions under which that figure is appropriate.

 

[JohnW2]

There are so many combinations and variables here - the number of conductors to be connected, their construction (solid/stranded), sizes and positions relative to each other and to the screw terminal - that I cannot see how a manufacturer can give any figure at all, without specifying the exact conditions under which that figure is appropriate.

Yes, I totally agree with that. However, when I tried it, the number, nature, size and positions of conductors in the various terminals were 'plumb standard' (i.e. incredibly common) - so if the recommended torques don't 'work' in that situation, I don't know what they would work for!

I wonder if the recommended torques were perhaps produced by mechanical engineers who were more concerned about the torque-tolerating properties of the screws/threads than of the adequacy of the electrical connection? Mind you, if that were the case, they could not have had much faith in their hardware, since the recommended torques don't seem to be anywhere need high enough to risk damaging screws/threads!

Kind Regards, John

 

[ban-all-sheds]

in many cases use of the manufacturer's recommended torque left me with a situation in which the conductor was clearly 'loose', and quite probably could have been pulled out

I am as certain as I can be without looking for an authoritative answer that the electrical terminations are not supposed to provide mechanical support or restraint. If the cables can move or be pulled out then you must provide a means to prevent that other than tightening up the terminals.

 

[JohnW2]

I am as certain as I can be without looking for an authoritative answer that the electrical terminations are not supposed to provide mechanical support or restraint. If the cables can move or be pulled out then you must provide a means to prevent that other than tightening up the terminals.

That's certainly true of things like soldering, but I don't think it's the point. I'm not really talking about the mechanical support, per se, but, rather, taking the relative lack of it to be suggestive of an unsatisfactory electrical connection. My feeling is that if the tightness (or lack of it) of the terminal is such that the conductor can be moved about (or even pulled out), if one tries, it seems very unlikely that there will be a satisfactory electrical connection, particularly not a satisfactory long-term electrical connection.

Kind Regards, John

 

[ban-all-sheds]

I come back to finding it incredible that an electrical manufacturer would recommend torque settings which did not result in a satisfactory electrical connection. Can you imagine the consequences they would face if devices installed according to their specification caught fire because their specification was wrong?

The only relevant experience I have is with car wheel nuts - I remember once, having always done them up "good and tight", using a torque wrench and being very surprised at how much less than "good and tight" the recommended setting was. And I know that doing them up too tight can damage the wheel.

 

[JohnW2]

I come back to finding it incredible that an electrical manufacturer would recommend torque settings which did not result in a satisfactory electrical connection. Can you imagine the consequences they would face if devices installed according to their specification caught fire because their specification was wrong?

I agree. It's hard to understand. However, I can but report my experiences, which are similar to flameport's. Maybe I'm totally wrong, but I would not personally regard it as remotely safe to leave terminals in a CU done up as loosely as the recommended torques.

If my/flameport's experiences are typical, there would be little doubt that most people tighten terminals to greater torques than these recommendations, yet we still hear lots of stories of thermal damage, fires or failures due to 'loose connections'. Indeed, even the LFB seem to acknowledge that!

Kind Regards, John

 

[ban-all-sheds]

I agree. It's hard to understand.

But not hard enough for you to accept that it must be right even if you don't understand it.

Do you have any credible explanation, or reasonable theory, of why the makers would specify a torque which was inadequate?

Maybe I'm totally wrong, but I would not personally regard it as remotely safe to leave terminals in a CU done up as loosely as the recommended torques.

So if I understand you correctly, you have not designed the terminals, you have not specified the materials used, you have not done any testing of torque settings, you have no idea how or why the makers specify what they do, but you refuse to accept it.

That really doesn't sound like the way to behave. Do you make it your practice in life to ignore everything which you are told by people with more expertise than you because you don't understand it?

Do you believe that 134.1.1 does not apply to torque values? And that's recently been diluted - prior to the 17th it said "Electrical equipment shall be installed in accordance with the instructions provided by the manufacturer of the equipment", so nobody who failed to observe the recommended torque was complying with BS 7671. Or do the MIs say "at least xNm"?

Yes - I'm one of those guilty as charged - I'd never thought about this before, but it seems to me that a torque setting screwdriver might be a mandatory tool, even if it isn't cheap.

If my/flameport's experiences are typical, there would be little doubt that most people tighten terminals to greater torques than these recommendations, yet we still hear lots of stories of thermal damage, fires or failures due to 'loose connections'. Indeed, even the LFB seem to acknowledge that!

How sure are you that those incidents have not arisen because people have erred on the other side of the recommended torque? Or are not due to damage caused by doing them up too tight?

I don't have a tool to check with, but I think it would be really useful if someone who did could contact a couple of manufacturers and

a) express the concern that at the recommended value it seems too loose

and

b) tell them what value they prefer to use

and ask them to comment on (a) and to say what, if anything, is wrong with (b).

 

[JohnW2]

So if I understand you correctly, you have not designed the terminals, you have not specified the materials used, you have not done any testing of torque settings, you have no idea how or why the makers specify what they do, but you refuse to accept it.

I wish you wouldn't try to make this an assault on me - it's a far more general issue than that. I'm sure I'm not alone, even if I'm wrong. How many electricians here do you think would be happy to leave a terminal in a CU which was so 'loose' that one could 'waggle the conductor around' and easily get half a turn, or maybe a whole turn, more with a screwdriver without much effort? I'm sure that there wouldn't be many, although you're technically right in saying that the majority might conceivably all be wrong.

Are you therefore happy to say that most people should probably tighten terminals far less than they are used to doing?

Kind Regards, John

 

[ban-all-sheds]

I wish you wouldn't try to make this an assault on me - it's a far more general issue than that.

I'm not, it's just that you're the one I'm discussing it with, and therefore you're the one who said the things which led me to say what I did.

Anybody who agrees with you may consider what I said directed at them also.

I'm sure I'm not alone, even if I'm wrong.

I'm as sure of that as I am sure that I've habitually tightened things up "too much".

How many electricians here do you think would be happy to leave a terminal in a CU which was so 'loose' that one could 'waggle the conductor around' and easily get half a turn, or maybe a whole turn, more with a screwdriver without much effort?

Very few, I expect, but that doesn't mean that they are right.

I'm sure that there wouldn't be many, although you're technically right in saying that the majority might conceivably all be wrong.

We keep coming back to to questions which cannot be ignored, like why would the makers specify a torque which was less than what was required, and which would leave the cables insufficiently clamped and not making a good enough contact? How could they arrive at an inadequate figure? In whose interests would that be?

I don't know the answer to those any more than you do, but what I do know is that my ignorance and lack of understanding are not reasons to dismiss what the makers say is the way to install their products and assume that I must know better.

Are you therefore happy to say that most people should probably tighten terminals far less than they are used to doing?

At the moment it would seem that they probably should. It definitely seems that they should certainly inform themselves of what the makers say, and what the risks are of exceeding the figures the makers specify.

 

[AndyPRK]

Look at a wylex REC2 isolator.

These don't offer any restraint for the tails. Only the terminals !