Should outer shield of T&E enter back box?

[Risteard]

Protection against what - earthquakes? What other than earthquakes would result in repetitive relative movement between cable and box?
Whether or not it represents 'crap installation practice' presumably depends whether it was done because an installer who believed that it should be done simply didn't bother or because it was the considered opinion of the installer that it was not necessary.

Kind Regards, John

Often with multiple cables entering the box you find that the cables are permanently being pressed against the sharp edges of the hole in the box. Believe me it's not uncommon. And completely unforgiveable given how easy (and cheap) it is to have done it correctly in the first place.

 

[JohnW2]

Often with multiple cables entering the box you find that the cables are permanently being pressed against the sharp edges of the hole in the box.

True - but you have introduced a new goalpost. You were talking about "abrasion", and that's not abrasion.

Don't get me wrong, I do use grommets - but, like so many 'precautionary' things I do, I am not convinced that they are necessarily addressing a particularly significant 'risk'.

Kind Regards, John

 

[Risteard]

or because it was the considered opinion of the installer that it was not necessary.

No Apprentice-trained Electrician would ever come to that conclusion though.

 

[Risteard]

I am not convinced that they are necessarily addressing a particularly significant 'risk'.

I never suggested that in all cases the risk is significant - I simply pointed out that it is required and is proof of absolutely crap installation if they are not present. It is wholly inexcusable in every respect.

 

[JohnW2]

No Apprentice-trained Electrician would ever come to that conclusion though.

Are you talking specifically about 'Apprentice-trained" electricians because you feel that they are likely to be indoctrinated with "... because that's the way we've always done it" practices?

Kind Regards, John

 

[JohnW2]

I never suggested that in all cases the risk is significant - I simply pointed out that it is required ...

As this whole discussion started, 'required' by what or whom? As has been said, as far as I am aware, BS7671 only requires that cables have adequate protection against mechanical damage - without, as far as I am aware, any specific mention of grommets.

... and is proof of absolutely crap installation if they are not present. It is wholly inexcusable in every respect.

As I've implied, that is really a matter of opinion and judgement in a particular situation, not an general and absolute truth.

Kind Regards, John

 

[ban-all-sheds]

It may be unlikely, but the fact remains that it hasn't been protected against.

So is abrasion the only thing that BS 7671 requires cables to be protected against?

I thought it also required them to be protected from things like heat, corrosion, damage from animals etc. How would you advise installing T/E into back boxes to guard against that sort of damage?

 

[ban-all-sheds]

Are you talking specifically about 'Apprentice-trained" electricians because you feel that they are likely to be indoctrinated with "... because that's the way we've always done it" practices?

Or because they are trained to not think for themselves?

 

[ban-all-sheds]

BS7671 requires that the cable be protected against abrasion.

What is the wording of the actual requirement?

 

[JohnW2]

Being "indoctrinated with '... because that's the way we've always done it' practices" is, indeed, probably part of the training not to think for themselves, since it's a type of training which, essentially by definition, is usually given by people who, in turn, have not thought for themselves.

 

[JohnW2]

Indeed (and protected against all sorts of other environmental influences).

 

[rsgaz]

Surely grommets are just there to protect the cable while you pull it into the box? Or a horizontal cable run through those awful steel stud walls (for a more 'worse case scenario' for damaging the sheath).

If there were any vibration against a sharp edge, it will just cut through the grommet first, and then the PVC anyway. Therefore you haven't 'protected the cable', just extended how long it will take before it gets damaged.

 

[John D v2.0]

To be honest I always thought grommets were to protect cables against slight movement in the back box when things were plugged into and out of sockets. Also switches that matswitched forter.
If it's solidly all in plaster then it's probably ok, but a loose back box is common enough.

 

[ban-all-sheds]

matswitched forter.

Nope.

Can't postulate a strange auto-uncorrect or voice-unrecognition which I could reverse to find out what you meant to say there....

 

[bernardgreen]

reverse to find out what you meant to say there....

Heavy handed operation of a switch ?