Surface socket box for square conduit/trunking.

[dishman]

I am replacing some surface mounted sockets in the garage which have have some rectangular conduit/trunking poorly fitted into it (not even properly attached).

I cannot tell if the sockets had pop outs for square conduit or someone diy bodged it and cut holes.It looks to be the latter.

https://www.tlc-direct.co.uk/Main_Index/Boxes_and_Enclosures_Index/Boxes_Surface_1/index.html

I assume this is the correct item to use, I am just surprised there seems to be such a small range. The order code suggests they are MK. Correct? Is it best to use MK fronts/sockets with these or will any brand fit?

Does every manufacturer have surface boxes with pop-outs designed foe rectangular conduit? Or only a few?

Do metal sockets only come with round pop-outs?

 

[Echo the husky]

There are other brands, Mita, Marshall Tufflex etc. Models of different depths, round corners, square corners and so on. I've only ever seen metal boxes with round holes, though some manufacturers make an adaptor to go from square mini trunking to a round hole.

 

[JohnW2]

... and, for some reason I've never really understood, they all seem to be made of PVC, rather than the urea-formaldehyde resin used for virtually all other 'white' electrical accessories.

Kind Regards, John

 

[dishman]

So does that mean they have less rigidity? Maybe that is the type of plastic required for the snap-out to break of cleanly and easily?

Do standard wall boxes have generic snap-outs (or weak areas to cut out)? It looks like who ever fitted the current ones just drilled entrance holes in the top. Although it looks like it was designed to be weaker in that area for that purpose, not sure.

Basically, is there a preferred brand to have a rectangular conduit (I understand I have to match it to my conduit dimensions) securely attach to a 32mm surface mounted box? Or is there another method I am not seeing.

If not, the ones in the link look decent enough I think.

Many thanks for the replies.

 

[JohnW2]

So does that mean they have less rigidity?

Yes. They are much softer, and just slightly bendable, as compared with the usual treacherously brittle boxes!

Maybe that is the type of plastic required for the snap-out to break of cleanly and easily?

Possibly - although, unlike the "treacherous" ones, they can be easily cut, drilled, filed or machined without shattering.

Do standard wall boxes have generic snap-outs (or weak areas to cut out)?

They usually have weak (thin) places to cut - but, even then, one has to be aware of the cracking/shattering risk.

Basically, is there a preferred brand to have a rectangular conduit (I understand I have to match it to my conduit dimensions) securely attach to a 32mm surface mounted box?

My experience of different makes is limited, but I don't think there is much to choose between them.

Or is there another method I am not seeing.

As has been suggested, you could probably use rectangular-to-round adapters, and then attach to round holes in a box (although it's usually only metal boxes that even have round knockouts).

Kind Regards, John

 

[Chri5]

Nothing a hole cutter won't sort (when you want round bush) even on a brittle b/bock (just go gently).

Boxes for mt1 and mt2 trunking have the rectangle knockouts that then allow the adapter to clip in. The trunking sits inside the adapter.

The boxes are standardised, since there isnt a size varience on mt1 or 2

 

[333rocky333]

... and, for some reason I've never really understood, they all seem to be made of PVC, rather than the urea-formaldehyde resin used for virtually all other 'white' electrical accessories.

Kind Regards, John

Is that not because they are designed to take a clip in trunking adapter, that people rarely use

 

[JohnW2]

Is that not because they are designed to take a clip in trunking adapter, that people rarely use

I don't really see why that means that they have to be made out of a material different from that which is almost universally used for all other 'white' electrical accessories.

Kind Regards, John

 

[rsgaz]

why that means that they have to be made out of a material different

Isn't it because urea formaldehyde is too brittle to be drilled easily and the dust is hazardous? Also, with PVC having a bit of flex, it will take up any irregularity in the wall, albeit sometimes making the faceplate look a bit crooked.

Gaz

 

[JohnW2]

Isn't it because urea formaldehyde is too brittle to be drilled easily and the dust is hazardous?

Maybe, but one could propose a similar argument in relation to any surface-mounting box, couldn't one? - they never come with ready-made cable entries.

Also, with PVC having a bit of flex, it will take up any irregularity in the wall, albeit sometimes making the faceplate look a bit crooked.

Again, I would think that could be said of any surface-mounted box.

Kind Regards, John

 

[rsgaz]

Maybe, but one could propose a similar argument in relation to any surface-mounting box, couldn't one?

Sorry John, I don't quite get the gist of what you mean there? I'm saying that PVC is really easy to drill and is not brittle or hazardous, ergo making it the ideal plastic for the boxes and trunking etc. Therefore you couldn't propose a similar argument for PVC boxes (not having a go BTW, just trying to explain). I was slightly answering your earlier comment at the same time; this one...

for some reason I've never really understood, they all seem to be made of PVC

Gaz

 

[JohnW2]

Sorry John, I don't quite get the gist of what you mean there? I'm saying that PVC is really easy to drill and is not brittle or hazardous, ergo making it the ideal plastic for the boxes and trunking etc.

I agree.

In fact, as I have already implied, I agree that, from the point-of-view of the ease of drilling, cutting, machining, trimming etc., PVC would be be preferable material for any surface mounted box (not just those intended for trunking). The problem with PVC is that is has inferior in-service properties to those of urea-formaldehyde, particularly in the presence of heat or fire (take a blowlamp to a PVC and a U-F one, and you'll soon see the difference ). That is presumably why nearly all white electrical accessories are made out of urea-formaldehyde resins?

Therefore you couldn't propose a similar argument for PVC boxes (not having a go BTW, just trying to explain).

I don't really understand what you are saying here - have I perhaps at least partially answered it above?

Kind Regards, John

 

[rsgaz]

I don't really understand what you are saying here - have I perhaps at least partially answered it above?

Yes, I see now. But earlier when we had....

Isn't it because urea formaldehyde is too brittle to be drilled easily and the dust is hazardous?

Maybe, but one could propose a similar argument in relation to any surface-mounting box, couldn't one? - they never come with ready-made cable entries.

...I thought that you were saying that one could argue that PVC was also too brittle to be drilled easily, as if you were implying that urea formaldehyde and PVC had similar mechanical properties, which you weren't.

Gaz



edit: ban-all-sheds was right you know, trying to put a 'quote in a quote' and realising you have to do it manually is a pain in the rear end!!!

 

[JohnW2]

...I thought that you were saying that one could argue that PVC was also too brittle to be drilled easily, as if you were implying that urea formaldehyde and PVC had similar mechanical properties, which you weren't.

Indeed. As I think you now realise, I was saying (I though clearly, but perhaps not clearly enough!!) that the argument (with which I certainly agree) that PVC was easier to work with (drill, cut, machine etc.) could equally be applied to ANY surface-mounted box (not just those intended for use with mini-trunking) - yet those other than the 'trunking' versions were invariably made out of urea-formaldehyde.

Kind Regards, John

 

[Iggifer]

I'm saying that PVC is really easy to drill and is not brittle or hazardous

Although some formulations smell like a certain 'erb when drilled. No idea why, think it may have been discussed on here before.