Grommets or conduit in metal back boxes?

[gembrain]

I've seen a few comments on failed installs because of lack of grommets - although apparently not a specific requirement as such.

Is oval conduit plastered into chase and fed a little into the back box OK or does one HAVE to cut it just short of the the box and fit a grommet?

Granted it's a sharp edge but where the cable comes in at the top of the conduit is the same.

Thanks

 

[telectrix]

i generally stop the oval tube about 1/4" above the box and fit a grommit. however, once plastered in, it's unlikely that the cable will chafe on the boc, so grommets are not an absolute necessity.

 

[KAS1]

Why bother at all lol

i generally stop the oval tube about 1/4" above the box and fit a grommit. however, once plastered in, it's unlikely that the cable will chafe on the boc, so grommets are not an absolute necessity.

 

[Octopus]

I always fit grommets to metal boxes.

 

[MDJ]

I always fit grommets to metal boxes.

Likewise here too

 

[stitch]

Same Here

 

[Engineer54]

Never really liked oval conduit, and on the rare occasions in the past when i've sunk a conduits into walls, i've used the what would have been circular standard 3/4'' (20mm) and took the conduit straight into the back box, chopping it off to size when ready for wiring. Other than that, always have, used grommets in any stud walling metal socket/switch back boxes and the like...

 

[stuartcourt]

whats a grommet ?

 

[markythesparky]

Wallace's friend!

 

[gembrain]

... in the past when i've sunk a conduits into walls, i've used the what would have been circular standard 3/4'' (20mm) and took the conduit straight into the back box, chopping it off to size when ready for wiring.......

So if I use the heavy duty round conduit (not exactly thin enough to have any sort of sharp edge) then I should be OK?

 

[markythesparky]

if you are using circular conduit, you should buy the male or female adapters for the end of it and it will fix to the back box!

 

[Engineer54]

As i stated, i just used the standard PVC conduit that you would use for surface work. As far as i remember, i used a sharp knife edge type paint scrapper to cut the conduit ends within the back boxes but you can use anything you like really. All worked out fine for me...

 

[Engineer54]

if you are using circular conduit, you should buy the male or female adapters for the end of it and it will fix to the back box!

Could do, but i would imagine that by including conduit fittings your going to reduce the internal diameter of the conduit at the ends. That will also introduce a snagging element when pushing T&E cables down the conduit!!

 

[markythesparky]

Could do, but i would imagine that by including conduit fittings your going to reduce the internal diameter of the conduit at the ends. That will also introduce a snagging element when pushing T&E cables down the conduit!!

Yes but it would be the proper way to do it and would constitute good working practice.

 

[Engineer54]

Yes but it would be the proper way to do it and would constitute good working practice.

If we were talking about a surface installation i would obviously agree with you. But as far as relatively short embedded conduit drops are concerned, i consider nothing wrong at all with my solution. Totally fit for purpose, as they say!! lol!!

 

[valleybilly]

As long as the wire has its double insulation intact & going into the metal back box no grommits are needed .

 

[markythesparky]

As long as the wire has its double insulation intact & going into the metal back box no grommits are needed .

Why do manufacturers make them then?

 

[MDJ]

As long as the wire has its double insulation intact & going into the metal back box no grommits are needed .

I disagree

 

[Andy78]

Why do manufacturers make them then?

Same reason you use condoms. You don't need to sheath your cable in a rubber device, but it can be safer if you do.

 

[Hants-Spark]

As long as the wire has its double insulation intact & going into the metal back box no grommits are needed .

Still not sure how I missed it but on a Part P assessment about 3 years ago the assessor went to a socket and found there was no grommit on the entry, he checked a few others to be sure it wasn't a bad habit I had got in to and then gave me a non compliance which I had to rectify, wouldn't let me do it there and then either, had to fix at a later date and send photo's.

 

[valleybilly]

Why do manufacturers make them then?

For Single insulated wire types

 

[MDJ]

For Single insulated wire types

Again I disagree, where's your spurs lol

 

[valleybilly]

Still not sure how I missed it but on a Part P assessment about 3 years ago the assessor went to a socket and found there was no grommit on the entry, he checked a few others to be sure it wasn't a bad habit I had got in to and then gave me a non compliance which I had to rectify, wouldn't let me do it there and then either, had to fix at a later date and send photo's.

This answer i was given was by ELECSA on my assesment 3weeks ago (ie no grommits needed), O Yer ! i fitted the grommits B4 assesment LOL

 

[valleybilly]

Again I disagree, where's your spurs lol

Where ever i like ! lol

 

[Hants-Spark]

This answer i was given was by ELECSA on my assesment 3weeks ago (ie no grommits needed), O Yer ! i fitted the grommits B4 assesment LOL

Not really sure what your trying to say but I'm with Elecsa and it was them during my assessment that picked me up on it.

 

[MDJ]

This answer i was given was by ELECSA on my assesment 3weeks ago (ie no grommits needed), O Yer ! i fitted the grommits B4 assesment LOL

I'm struggling to think of one type of installation where a metal knockout box designed for domestic installations can be used without a rubber grommet with single pvc cables going into it, if using single pvc cables then conduit would be used to connect to the box and therefore the cables would be protected from the metal hole by a coupler, interested to hear where a single cable entering a metal box could be used without any protection??

 

[valleybilly]

If you striped the outer insulation b4 the metal box its a fail , if its presant after where you fit the gommit then pass !

 

[Redvanman]

Niceic inspectors jump up and down about grommets not being used.
i always use them, good practice and all that, but if you take the conduit into the box I can't see a problem apart from the half wit plasterer pulling the conduit out

 

[markythesparky]

Why do manufacturers make them then?

For Single insulated wire types

But singles would be in conduit and you wouldn't need the grommet as the conduit would be fixed to the box.

 

[MDJ]

but you said for single insulated wires?

 

[valleybilly]

I'm struggling to think of one type of installation where a metal knockout box designed for domestic installations can be used without a rubber grommet with single pvc cables going into it, if using single pvc cables then conduit would be used to connect to the box and therefore the cables would be protected from the metal hole by a coupler, interested to hear where a single cable entering a metal box could be used without any protection??

Thats due to you replying to a completly different answer

- - - Updated - - -

not always

 

[MDJ]

Thats due to you replying to a completly different answer

umm, no, you said single cables entering, I said I can't think of one installation method which would allow that, and even if the cable is PVC/PVC a grommet is the proper way, come on now you know were right, give it up lol

 

[Hants-Spark]

Thats due to you replying to a completly different answer

- - - Updated - - -

not always

Just out of curiosity what question was MDJ answering then if it wasn't the one you posed, I've re-read the thread and it all flows through to the same thing, cables entering a box either via a grommit as has been said or your way which says otherwise??

 

[markythesparky]

MDJ, i think he's on the ropes! ;-)

 

[valleybilly]

Dependant with whom you are reg'd with im sure your answer will be differant ,


If you don't use em the part p police will take you away , NOT ! lol.

 

[MDJ]

Dependant with whom you are reg'd with im sure your answer will be differant ,


If you don't use em the part p police will take you away , NOT ! lol.

None of the scams will recommend running single cables without protection into metal knockout boxes direct without any protection, it just cannot happen, against all regs, single cables are usually run in plastic or metal conduit, sometimes if they are double insulated they can be run otherwise but protection into a metal enclosure would be expected by any professional.

 

[Hants-Spark]

Dependant with whom you are reg'd with im sure your answer will be differant ,


If you don't use em the part p police will take you away , NOT ! lol.

Didn't mention being taken away, although my wife would no dount be a happier women it was given as a non-compliance and needed rectifying before I was passed

 

[pennywise]

I use 20mm PVC conduit and couplers with male bushes, no need for grommets and easy to pull additional switch lines down if customer changes there mind.

 

[valleybilly]

Just out of curiosity what question was MDJ answering then if it wasn't the one you posed, I've re-read the thread and it all flows through to the same thing, cables entering a box either via a grommit as has been said or your way which says otherwise??

As long as the wire has its double insulation intact & going into the metal back box no grommits are needed .

Singles (which dont have double insulation ) then grommits or other methods may be used .

 

[Hants-Spark]

As long as the wire has its double insulation intact & going into the metal back box no grommits are needed .
And this is what your Elecsa assessor said to you? Because mine gave me a non-compliance and said I need to rectify before passing.

Singles (which dont have double insulation ) then grommits or other methods may be used .

I beleive MDJ was asking for an example when you would use singles within a domestic installation not installed within conduit and just entering a metal box without a metal bush etc? MDJ can correct me if I'm wrong