Anyone seen this before?

[mikhailfaradayski]

Although they have stringent testing procedures in place for such joint boxes, and many on the market actually fail! There was an article about it somewhere...

Now then, shall we put that statement down to urban myth, complete and utter billhooks or shall we see a link to the article? - I think I know the answer....

As for those particular lamp holders, I have seen many of them, and i have always thought that those particular types are very poor quality. I wouldn't for a minute class them in the same league as the spring terminals which are now permitted under the current regs. Chalk and cheese, me thinks

 

[scousespark]

Although they have stringent testing procedures in place for such joint boxes, and many on the market actually fail! There was an article about it somewhere...

That doesn't surprise me, and I've certainly never felt comfortable about them (or any other sort of joint, apart from soldered/brazed) being inaccessible, whatever the IET may think!

Kind Regards, John.

I don't have an issue with you, or anybody having an opinion, until you imply that you know better than the IET.

 

[JohnW2]

I don't have an issue with you, or anybody having an opinion, until you imply that you know better than the IET.

Same here - I'm sure none of us would want to live in a world in which individuals were not allowed to have, and express, opinions. As for 'who knows better' than anyone else, one can but presume that anyone who expresses an opinion actually believes it, and therefore, by implication, disagrees with those who have differing opinions - but that's what 'opinions' are all about, isn't it?

Kind Regards, John.

 

[securespark]

Don't forget, some practices have been employed in previous regulations and been dropped from later editions.

The regulations are ever-evolving and additions or alterations to the latest book are not necessarily permanent. If over time some regulations don't work, they will be reworked or omitted.

A good example is supplementary bonding in kitchens.

How successful MF JB's will be will depend upon how thorough and extensive their development and testing has been.

You know when car manufacturers are developing new models or drivetrains?

They'll put the running gear into existing models and run it for 100's of thousands of miles in varying conditions.

It may prove reliable, but when the car is sold by the thousand, suddenly problems crop up that were not seen during the test period.

 

[JohnW2]

How successful MF JB's will be will depend upon how thorough and extensive their development and testing has been. You know when car manufacturers are developing new models or drivetrains? They'll put the running gear into existing models and run it for 100's of thousands of miles in varying conditions. It may prove reliable, but when the car is sold by the thousand, suddenly problems crop up that were not seen during the test period.

Exactly. Although I've often been mis-/over-interpreted, that is all I've ever been intending to say - coupled with the fact that I am not all that keen on volunteering my home as a testbed for a product which has not been in widespread routine use for a long time!

One of the problems is that, despite challenges, no-one has really been able to produce or locate any statsitics on the long-term performance of screw-terminal junction boxes - so, even after they have been in widespread use for a good few years, it's going to be difficult to tell whether 'MF' ones actually are appreciable more reliable, or associated with appreciably fewer problems. I suspect that, as with crimps (and, indeed, screwed joints), the majority of problems are probably going to arise as a result of joints which were not made properly in the first place (and it's certainly possible to install an 'MF' JB 'imperfectly') - but that's often going to be hard, if not impossible, to ascertain if/when they develop problems a number of years down the line.

Kind Regards, John.

 

[17thman]

How successful MF JB's will be will depend upon how thorough and extensive their development and testing has been. You know when car manufacturers are developing new models or drivetrains? They'll put the running gear into existing models and run it for 100's of thousands of miles in varying conditions. It may prove reliable, but when the car is sold by the thousand, suddenly problems crop up that were not seen during the test period.

Exactly. Although I've often been mis-/over-interpreted, that is all I've ever been intending to say - coupled with the fact that I am not all that keen on volunteering my home as a testbed for a product which has not been in widespread routine use for a long time!

One of the problems is that, despite challenges, no-one has really been able to produce or locate any statsitics on the long-term performance of screw-terminal junction boxes - so, even after they have been in widespread use for a good few years, it's going to be difficult to tell whether 'MF' ones actually are appreciable more reliable, or associated with appreciably fewer problems. I suspect that, as with crimps (and, indeed, screwed joints), the majority of problems are probably going to arise as a result of joints which were not made properly in the first place (and it's certainly possible to install an 'MF' JB 'imperfectly') - but that's often going to be hard, if not impossible, to ascertain if/when they develop problems a number of years down the line.

Kind Regards, John.

good point. I would however contend that the failure rate of junction boxes over crimped connections, if it is measured, maybe be that crimp connections are probably more often made by professionals.

 

[JohnW2]

good point. I would however contend that the failure rate of junction boxes over crimped connections, if it is measured, maybe be that crimp connections are probably more often made by professionals.

Could be - but I'm used to dealing with proper 'data/evidence', and no-one has yet been able to provide me with, or point me to, any in relation to these issues. IF crimped connections do fail less often than screwed ones, then it might be due to what you suggest. However, it could also be the case that there are more initially imperfect connections with crimps, even in the hands of professionals - most of whom will have vastly more experience of making screwed connections than crimped ones.

Therein also lies another problem I've mentioned in the past, which (in the absence of hard facts) undoubtedly influences perceptions of relative failure rates of different types of connections. There are vastly more screwed connections out there than crimped ones. As a wild guess, let's say that there are 200 screw terminals for every crimp. I suspect that may markedly over-estimate the number of crimps around but, even if the ratio were just 1:200, it would mean that, even if the failure rate were the same for both, people would, on average, see 200 screwed connection failures for every crimp failure they saw. Unless proper large-scale statistics are collected (very unlikely), we're probably going to have the same problem with 'MF' JBs - for many years to come, we are going to be seeing far more failures of conventional JBs than of 'MF' ones, regardless of whether 'MF' ones are better, the same or worse - simply because there are still going to be so many more conventional JBs out there - and, in the absence of hard data, that is bound to have some influence on at least some people's perceptions.

Kind Regards, John.