Terminating unused electric cable

[JohnW2]

The house I'm doing up uses standard junction boxes to connect the ring main to each transformer. Is this okay, because it is the transformer that is wired to the light fitting, or should the JB's have cable restraint?

For obvious reasons, any JBs should really (and in order to be regulation-compliant) have cable restraint, and that has been true for a long time. That can either be achieved by using JBs which have facilities for cable restraint within them or, if using a 'standard' JB, by attaching the JB to something solid (e.g. a joist) and clipping the cable to that same joist/whatever. Having said that, I have no doubt that there are millions of standard JBs out there with unrestrained cables - so draw whatever conclusions you may wish from that.

Kind Regards, John

 

[EFLImpudence]

Indeed, that is true of 'standard' JBs.

That is what OP is discussing.

 

[EFLImpudence]

if using a 'standard' JB, by attaching the JB to something solid (e.g. a joist) and clipping the cable to that same joist/whatever.

That is difficult to achieve through a hole in the ceiling.

Having said that, I have no doubt that there are millions of standard JBs out there with unrestrained cables - so draw whatever conclusions you may wish from that.

The conclusion is that they are no longer allowed for the application in mind.

Purpose manufactured JBs have been made because of this.

 

[JohnW2]

Indeed, that is true of 'standard' JBs.

That is what OP is discussing.

It is - and I agree that I should have mentioned that when I talked about JBs which are 'accessible' through downlight holes.

However, when there is no strain restraint, such JBs are strictly non-compliant (even if common!) for reasons other than non-accessibility (which is "what OP is/was discussing").

Kind Regards, John

 

[JohnW2]

if using a 'standard' JB, by attaching the JB to something solid (e.g. a joist) and clipping the cable to that same joist/whatever.

That is difficult to achieve through a hole in the ceiling.

I wasn't meaning to suggest that it was - I was talking generally about how to achieve cable restraint with JBs!

Having said that, I have no doubt that there are millions of standard JBs out there with unrestrained cables - so draw whatever conclusions you may wish from that.

The conclusion is that they are no longer allowed for the application in mind. Purpose manufactured JBs have been made because of this.

Indeed so. However, the OP was talking about a 'fait accomplis' (JBs without cable restraint which were installed a few years ago), so I'm not sure that 'bringing up to current standards' is actually required, even though they were non-compliant (by virtue of absent cable restraint) even when installed. What would be your view?

Kind Regards, John

 

[EFLImpudence]

I would think that 'an electrician' would be uncomfortable using the existing when fitting new lights.

Contrary to what the OP says, they (J501) are not exactly expensive, depending on where they are bought, of course.

 

[Milleniumaire]

Sorry, I confused things by asking different questions.

Thanks for the feedback from everyone, I've certainly learned a lot about building regs regarding the use of junction boxes and terminating cables and will be scrutinising the work of the electrician when he comes round

 

[JohnW2]

I would think that 'an electrician' would be uncomfortable using the existing when fitting new lights.

That's probably true, but there has been no suggestion that the OP will want those lights replacing any time soon - he was merely mentioning what an electrician (or 'electrician') did 4 years ago.

Contrary to what the OP says, they (J501) are not exactly expensive, depending on where they are bought, of course.

I would personally agree. In fact, I think that they are comparable in price with MK and Ashley 'standard' JBs. However, the OP probably has in mind the fact that they are 2-3 times more expensive than 'cheap standard JBs'. However, even then, the difference in cost is likely to be fairly trivial in relation to the total job of replacing lights (parts plus labour).

Kind Regards, John

 

[PBC_1966]

Let's introduce some pragmatic thought here: In a house of this age which, by the sounds of it, certainly hasn't had a full rewire in a long time, there are probably many other junction boxes under floors and in other places which might not be regarded as accessible today. In an ideal world it might be nice if the other end of that cable could be located and disconnected. There's a chance it might actually just be tapped from some other easily accessible lighting outlet or switch box rather than being from some other hidden junction box, in which case it could be. But if it can't be located and disconnected easily, the solution Milleniumaire has adopted following the advice given here is certainly far better than his original idea about just taping up and burying in the wall, and as Bernard has pointed out, the now-hidden junction box will not be carrying any current anyway since it's a dead-end cable.

Frankly, from what I saw of the so-called "maintenance-free" junction boxes of more recent years in the U.K., I wouldn't trust them to be any more reliable when not accessible than I would a regular screw-terminal type anyway.

A couple of more general points:

In my house ALL cables are "within a wall" or "under floorboards". So does that mean none of them are accessible?

The current rules in BS7671 require that non-maintenance-free junction boxes and other connection points be accessible, but not the cables themselves. If cables had to be accessible throughout their length it would make it practically impossible to ever run them within the fabric of the building rather than on the surface.

So, if 'under floorboards" is not usually regarded as 'accessible' why are "standard" junction boxes used to connect cables?

As mentioned already, there are still places where they would be regarded as accessible, such as in an attic. And by the way, this whole business is a rule within BS7671 (the generally accepted standard for wiring in the U.K.), not within the actual building regulations.

As with some other rules, sometimes people can't agree on a definition of "accessible." I think most people would be in agreement that a junction box hidden inside a stud wall with no access but for cutting a hole in the wall is inaccessible and that a surface mounted one on a wall clearly is accessible, but there's room for a grey area where opinions might differ.

Back in the early 1970's my father completely rewired the 1930's home we moved into when I was young, and ended up using quite a few junction boxes under the floors, including the upstairs. But after pulling up floorboards for the rewire, he was quite meticulous in making sure that at every point where a junction box was located he fitted battens and small, easily removable sections of floorboard which were screwed down rather than nailed and were marked to indicate a junction below. He even did that on the downstairs which had a small crawl space beneath so that they could be accessed from above without the need to crawl under the house again.

Personally, I would say that if done like that today I would regard those junctions as accessible.

 

[JohnW2]

Frankly, from what I saw of the so-called "maintenance-free" junction boxes of more recent years in the U.K., I wouldn't trust them to be any more reliable when not accessible than I would a regular screw-terminal type anyway.

Indeed - I've often voiced that concern. Things will be a bit clearer in a number of years/decades but, until then, we inevitably have to rely on 'accelerated testing' (and 'theory') to give us an indication of how these things will probably behave in long-term real-world service.

Kind Regards, John

 

[PBC_1966]

My bet is that in 20 years or so all those "maintenance free" junctions which are buried away will be giving far more trouble than a "normal" junction box which by that time might have been in use undisturbed for 40 years or more. I guess we'll have to wait to see if we're right!

 

[JohnW2]

My bet is that in 20 years or so all those "maintenance free" junctions which are buried away will be giving far more trouble than a "normal" junction box which by that time might have been in use undisturbed for 40 years or more. I guess we'll have to wait to see if we're right!

I don't know enough to be able to speculate like that but, as you say, there is definitely some uncertainty - so, indeed, we will need to wait a decade or three to actually know.

We've been through all this with optical discs and 'non volatile' semiconductor memory (and many other things). Despite claims (based on some 'accelerated testing' etc.) when such things first appeared on the scene, we really had no clear idea as to how 'reliable' they would be in terms of very long-term storage reliability.

Kind Regards, John

 

[ban-all-sheds]

And by the way, this whole business is a rule within BS7671 (the generally accepted standard for wiring in the U.K.), not within the actual building regulations.

Indeed, but as compliance with BS 7671 is by far and away the only sane, practical way to comply with the Building Regulations, the "non-compulsory" nature of it fast approaches a moot point.

 

[Taylortwocities]

 

[JohnW2]

.... as compliance with BS 7671 is by far and away the only sane, practical way to comply with the Building Regulations....

That's probably more-or-less true in practical terms but, in terms of what the law (the Building Regulations) "actually says", there is no absolute guarantee that compliance with BS7671 automatically means compliance with the Building Regulations.

Kind Regards, John