New Consumer Unit

[ban-all-sheds]

That's one way of wording it, and you are free to put it like that if you wish. I would prefer to say that unless/until I see some convincing evidence indicating that I should do otherwise, I am going to continue to do what, as I understand it, is what the great majority of electricians have regarded as the safe thing to do for decades.

So you want to see some convincing evidence to indicate that you should stop ignoring what the makers say because right now you believe that you know better than them how their products should be installed.

Play around with the wording however you like - that is your position - you cannot provide any explanation or theory of why they would specify an inadequate torque but nevertheless you have decided to assume that they have.

 

[AndyPRK]

I notice they have labels on them requesting you to re-tighten the factory fitted wires.

I guess you could blame that on the shipping vibrations.

To me it sounds like a disclaimer, or a statement to tighten as you see fit.

 

[flameport]

Is the recommended setting for a B6 the same as that for a 100A switch, 80A RCD etc?

In many cases, yes it is.
http://www.neweysonline.co.uk/neweys/pdf/WI00_Torque_Setting_Data_Technical.pdf

 

[JohnW2]

Is the recommended setting for a B6 the same as that for a 100A switch, 80A RCD etc?

No ... but what I couldn't tell you without checking is whether it is the same for a B6 and a B32, or even a B45. As I mentioned before, if mechanical engineers are behind this, their normal practice would be to specify tightening torques in relation to the size, material and thread patterns of the screws (hence possibly the same for the whole range of MCBs), conceivably with not much (any?) consideration of the electrical side of things, or the fact that some may be 'gripping' a 1mm² copper conductor, another 'gripping' 1, 2 or 3 2.5mm² conductors and another a 10mm² conductor.

I will ask you the question which nobody seems able to answer - why would a maker specify a torque setting which was inadequate?

There's obviously no point in your asking me a question which, as you say, nobody (presumably apart from those who produced these figures) can answer!

Consider the liabilities they would face if it could be shown that their inadequate spec was causing problems. They must have done what they at least consider due diligence to arrive at figures, they must be sure that cables won't fall out or overheat.

I've already agreed with all that.

If people don't trust them to do that, I wonder what else they don't trust them to have got right.

Good question.

Kind Regards, John

 

[AndyPRK]

Ppl don't trust them to make mcb's without batch faults.

Or from robs video, flame retardant material on the covers.

 

[JohnW2]

In many cases, yes it is.
http://www.neweysonline.co.uk/neweys/pdf/WI00_Torque_Setting_Data_Technical.pdf

The consdierable degree of consistency between makers makes one wonder about BAS's belief that "They must have done what they at least consider due diligence to arrive at figures, they must be sure that cables won't fall out or overheat.". Maybe one company once went through that process, but it looks very much to me as if the figures are probably not the result of extensive 'duly diligent' investigation - but, rather, in many cases metric equivalents of very-round-number imperial figures which sound very much like 'guesstimates' (15 & 20 lbf.in featuring all over the place in the various manufacturers' figures)!!

As has been suggested, it also seems rather (very) odd that the torque for an 80A RCD with, say, 16mm² conductors should be the same as for a B6 with 1mm² conductors. Again, that does not really sound much like an empirical result or the consequence of "due diligence", particularly when the answer equates to a nice round 15 lbf.in

Kind Regards, John

 

[Adam_151]

Torque Settings in my mind have their place, and that is where all the other variables have been fixed as well.

Parts of your car manufacturered to a tolerance. The bolts holding an MCCB onto the busbars in a panelboard. But for terminals which have variations in what size, type and number of conductors they are holding, they are a very course way trying to control connection quality. Far better to leave it to the skilled person to judge onsite.

 

[flameport]

Ppl don't trust them to make mcb's without batch faults.

Or to not use their influence to have BS7671 altered so they can ensure all-metal consumer units are compulsory, and then make and sell metal CUs at a significantly higher price to ensure profits are increased.

 

[JohnW2]

Torque Settings in my mind have their place, and that is where all the other variables have been fixed as well. Parts of your car manufacturered to a tolerance. The bolts holding an MCCB onto the busbars in a panelboard. But for terminals which have variations in what size, type and number of conductors they are holding, they are a very course way trying to control connection quality. Far better to leave it to the skilled person to judge onsite.

I agree totally. Electrical terminals just aren't in the same ballpark as mechanical connectors, for which specified tightening torques are designed primarily to prevent damage to screws/bolts, threads or the materials they are joining. As I've just said, most of the quoted torques have the appearance of simply being round-figure 'guesstimates', which largely ignore variation in terminal size or conductor size/number - which surely cannot be the result of much 'science'?

As you say, in the case of electrical terminals, I feel sure that the judgement of an experienced person is likely to be much better/safer than these almost 'generic' (and possibly largely 'arbitrary') torque figures.

Kind Regards, John

 

[AndyPRK]

It's good manufacturing engineering to not have 10 different torques unless required.

I.e to common some together.

But Newlec are taking it a bit far saying and rcd is the same as a mcb and the same as an earth terminal screw.

 

[Iggifer]

I notice they have labels on them requesting you to re-tighten the factory fitted wires

Not a board, but I fitted a 12v fan transformer yesterday, and an LED picture light today, and in BOTH, factory fitted cables fell out of the transformer secondary. Ugh, these people need a smack

 

[JohnW2]

It's good manufacturing engineering to not have 10 different torques unless required.

Tell that to car manufacturers However, you're right, but one should really design so as to not need lots of different torques, not create a design which requires lots of different torques and then 'combine some together'. However, as I've recently written, I'm not sure how applicable the usual mechanical engineering view of tightening torques is to the special case of electrical terminals (when something other than 'mechanical fastening' and protection of the fasteners is important).

But Newlec are taking it a bit far saying and rcd is the same as a mcb and the same as an earth terminal screw.

It's not just Newlec - all the makes included in your link are much the same. The ABB ones are generally appreciably higher than everyone else's, so maybe they did a bit of 'independent thinking/research'!

Kind Regards, John

 

[ban-all-sheds]

To me it sounds like a disclaimer, or a statement to tighten as you see fit.

Why doesn't it sound to you like a statement to tighten them to the specified values?

 

[AndyPRK]

Because it doesn't state the specified values.

 

[ban-all-sheds]

There's obviously no point in your asking me a question which, as you say, nobody (presumably apart from those who produced these figures) can answer!

So you cannot answer the question. You cannot come up with any reason why they would specify a figure which was wrong, you agree that they could be in deep **** if they were wrong (given that people might die from them being wrong), but nevertheless you have decided that they must be wrong.