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.