MK Grid Plus back boxes

[JohnW2]

Having just installed one, I'm reminded of something I've often wondered ...

... is there some rational reason (that I'm 'missing') why the back boxes (both 'flush' and 'surface') for MK Grid Plus switches/modules have (20mm) knockouts on top, bottom and both sides, but not on the back. In my recent install, I needed 'back entry', so had to make a hole for myself.

Kind Regards, John

 

[sparkwright]

I don't think there's a 'rational' reason as such.
But then again, metal clad sockets and switches don't have knock-outs in the back of their surface boxes either.

 

[JohnW2]

I don't think there's a 'rational' reason as such.

As I wrote, I certainly can't think of any!

But then again, metal clad sockets and switches don't have knock-outs in the back of their surface boxes either.

Yes, I should have mentioned that. I wrote only of the grid boxes since that what I've recently installed - but, as you say, exactly the same is true of metalclad surface boxes - again for no rational reason I can think of. In contrast, almost all other types of back boxes do have rear knockouts.

I guess it's not intended to be rational, logical or necessarily sensible

Kind Regards, John

 

[sparkwright]

I must admit, it's rare when I need to make a hole in the back of a metal clad switch/socket, OR a grid switch.
Come to think of it, a standard 25mm double knock-out box tends to only have four knock-outs in the back, when there is potentially room for eight.

 

[JohnW2]

I must admit, it's rare when I need to make a hole in the back of a metal clad switch/socket, OR a grid switch.

Same here - but the need does occasionally arise, as it did for me last weekend - and I can think of no reason why they couldn't/shouldn't put knockouts on the back. Nor can I really think of why one would be less likely to want rear entry into a 'grid box' than the into the back box for any switch or socket, can you?

Come to think of it, a standard 25mm double knock-out box tends to only have four knock-outs in the back, when there is potentially room for eight.

Indeed, but at least they have some! Even just one would be better than nothing (although I suppose it would never be 'where one wanted it to be'!)

 

[Harry Bloomfield]

Same here - but the need does occasionally arise, as it did for me last weekend - and I can think of no reason why they couldn't/shouldn't put knockouts on the back. Nor can I really think of why one would be less likely to want rear entry into a 'grid box' than the into the back box for any switch or socket, can you?

It takes a little longer, but with no KO's, you can make the rear entry, exactly where you want it, rather than being confined to having to use them where the manufacturer decides they shoud be.

 

[JohnW2]

It takes a little longer, but with no KO's, you can make the rear entry, exactly where you want it, rather than being confined to having to use them where the manufacturer decides they shoud be.

That's true - but, particularly if there are several, there will usually be one in a place one can use. I don't recall ever having had any major problems with the position of knockouts on standard steel boxes.

In any event, this doesn't answer the question as to why grid boxes and surface metalclad ones differ from all the others in this respect!

 

[Harry Bloomfield]

I don't recall ever having had any major problems with the position of knockouts on standard steel boxes.

Maybe our experience differ then, because I do remember such problems.

 

[JohnW2]

Maybe our experience differ then, because I do remember such problems.

Individual experiences obviously do vary - otherwise they would not be individual experiences

However, I suspect that our experiences of this issue are pretty limited. Mine certainly are, and I suspect the same is very probably true for you (and, indeed, probably most people) since it is pretty rare that one wants cables to enter the back of a metal back box.

 

[333rocky333]

What boxes do you mean, im pretty sure they do have one knockout in the back centre and four fixing slots, the lack of knockouts i assume because they have prioritised the fixing slots.
To me the standard flush boxes with the four rear knockouts often hinder where you want the fixings to go

 

[JohnW2]

What boxes do you mean, im pretty sure they do have one knockout in the back centre and four fixing slots, the lack of knockouts i assume because they have prioritised the fixing slots.

I have a fair selection on my shelves - MK grid boxes (surface and flush, single and double) and surface metalclad boxes (various makes and ages, both single and double) - and I can assure you that none of them have any knockouts on the back (although all have knockouts on all four sides. Some of the metalclad ones have one or two 'fixing slots', as well as round fixing holes, but the grid boxes only have round fixing holes.

I could take photos to prove the above statements (and will, if you really want me to!), but I would hope that you can trust me to be telling the truth!

To me the standard flush boxes with the four rear knockouts often hinder where you want the fixings to go

That can very occasionally be an issue, but is usually fairly easily got around. Mind you, as I recently wrote, I doubt that any of us require rear cable entry all that often, so the absence of knockouts is not a major issue - more something I've just been curious about

 

[plugwash]

Hmm, when I look at the metalclad plus grid boxes, they do seem to have rear knockouts.

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[JohnW2]

Hmm, when I look at the metalclad plus grid boxes, they do seem to have rear knockouts.

Interesting.

I find that I partially lied. Although I have some on my shelf, I have very rarely used surface grid boxes, and the one I recently used (which reminded me of this issue) was certainly a 'flush' one. Having now looked more carefully, the surface ones (lower pair in pic below) are, indeed, as per the pics in your link - with one central knockout in the rear and fixing 'slots' (rather than circular 'holes')

However, in the case of the 'flush' ones (upper pair in pic below), there are definitely no rear knockouts in mine, and there are circular fixing holes (rather than slots). So, either things have changed (it may be quite some time since I bought these) or the ones I have (marked "MK") are (imperfect!) 'fakes')!

 

[ebee]

I can imagine cost might be an issue (hunders of thousands of farthings add up , or some manufacturers act as if tgey do) so if it is deemed very unlikely that the metalclad type boxes had much use for a rear hole or three in comparison to the more usual humble metal back box used for fush sockets and switches might just save tge compsny a few pennies each year.
Any one actually needing a rear hole would make their own where needed.
Well i can not think of another reason but most plastic patresses have a rear knockout or three though!

 

[JohnW2]

I can imagine cost might be an issue (hunders of thousands of farthings add up , or some manufacturers act as if tgey do) so if it is deemed very unlikely that the metalclad type boxes had much use for a rear hole or three in comparison to the more usual humble metal back box used for fush sockets and switches might just save tge compsny a few pennies each year.

Who knows - but what you suggest couldn't explain there being rear knockouts in the surface boxes but not the corresponding flush ones, would it ?