MF connectors

[ban-all-sheds]

I've been thinking. (Often a dangerous thing.)

A forthcoming makeover of the bathroom in BAS Towers will bring about some wiring changes which will result in the retirement of my method of a contactor-switched fan, triggered by the operation of a clunky great shower isolator, and needing clunky great conductors for the contactor coil connection, and the introduction of a contactor switched shower, triggered by a normal switch and 1/1.5mm² conductors. (Yes there will be an isolator as well for the shower supply).

So I'm going to end up with an enclosure for the contactor, and figured I might as well use DIN rail terminal blocks for joining/distributing light and fan connections.

Now - I actually need more such terminals like I need to take a holesaw to my head, but I thought I'd have a go with the Wago push and/or lever connectors (773- / 222- series), with the DIN rail mount accessories.

Which is what got me thinking. I don't need MF connections, as the contactor has screwed ones, so the whole thing will need to be accessible. But even if I used only MF joints in it the enclosure would not be marked MF, and so the whole would not be.

Anybody have any idea why the mark on the enclosure is regarded as vital?

 

[333rocky333]

only a quess but could it be the fact that to get MF aproval the enclosure has to have cable restraint adequate to allow it to be classed as MF.
I know the hagar has screw down bar type clamp and the wago has a sort of push in wedge type clamp and im sure I once saw a round J/b that had push in terminals and screw down bar type clamps but they seem to have vanished off the market

 

[PrenticeBoyofDerry]

I once spoke to a leading engineer who was involved in the design of the Wago boxes, If I recall correctly, he said that the Wago boxes complied to the MF standard only if the box lid was secured by using a cable tie. Obviously you would require MF connectors inside. I forget the guys name but I have scribbled down somewhere!

 

[ban-all-sheds]

Well, as you know, I have a problem with those boxes, because they look the same on the outside whether inside they have the Wago connectors or not. They are going to say "maintenance free" on them even if they contain choc-blocks, wirenuts, or just wires twisted and taped. And I remain certain that one day someone will open one and find one of those things going on.

Opening them is a very relevant action. The labelling of the enclosures is not done to provide surface texture enrichment for mice, it's to tell people something of value, to give them useful information which they can process in a meaningful way. If the box is known about, and is not concealed, or has not been given drug-smuggler grade concealment, it will be easy or fairly easy for you to come across that information. But in those circumstances it doesn't need to be MF in the first place - it's accessible for inspection and maintenance. I wonder how likely it is that someone who is inspecting and checking the installation will think "I have no need to look inside that box, as it is MF, and therefore there cannot be anything in there which is wrong"? Not very, IMO.

Consider one which has been fiendishly hidden - maybe it is only discovered after you've spent weeks tearing floors up and hair out trying to find a fault. Again - is the MF label going to make you say "Well that's an MF junction box - the problem can't be in there, I'd better keep looking"? No, IMO.

So when you think about it, the MF label does not guarantee that the joints inside have been properly made, it does not guarantee that the cable restraints have been properly used, and it does not make any difference to what someone unfamiliar with it does when they encounter it. Which seems to make the information valueless, and if it is valueless why make it a mandatory requirement?