Maintenance Free vs Maintained Junction Boxes?

[sergeantash]

The phrase 'Maintenance Free' junction box came up during another thread and so I'm now curious as to what defines/differentiates the two, and the circumstances where you'd use one over the other?

I assume maintenance free is if installing into a location that you may theoretically never gain access to again without destroying things to get there?

Would is almost be best practice to always use a Maintenance Free junction box for peace of mind, as I assume it provides more robust connections?

I'd appreciate your feedback?

 

[sparkwright]

If the maintenance free junction claims to be compliant in inaccessible places then it would seem reasonable to fit them in such places.

I suppose by that token it may be sensible to fit these in places which may become inaccessible in the future.

Whether these things are any good, it's possibly too early to say.

Screw terminals are not supposed to be inaccessible. They are supposed to work loose. I'm not certain they do.

Cue the opening of the can of worms.

 

[studentspark]

The twist on connectors have appeared in my local CEF. They seem popular in america.
Would be interested in what people think of these.
Found some old porcelain ones under floor boards the other day.

I like the wago leaver connectors

 

[AndyPRK]

Would is almost be best practice to always use a Maintenance Free junction box for peace of mind, as I assume it provides more robust connections?

No.

 

[sergeantash]

Would is almost be best practice to always use a Maintenance Free junction box for peace of mind, as I assume it provides more robust connections?

No.

Interesting responses everyone, Andy could you expand on your answer as to why?

 

[riveralt]

Would is almost be best practice to always use a Maintenance Free junction box for peace of mind, as I assume it provides more robust connections?

No.

Interesting responses everyone, Andy could you expand on your answer as to why?

What is there to explain - what you are talking about it not best practice. Design your circuits so you don't have to use inaccessible junction boxes and if you cannot then consider alternatives such as crimping or accessible junction boxes.
Every time you create additional links in the circuit you are creating a potential problem.
But since you seem to use jb's in inaccessible places, don't bother with building control or test your circuits before energising - you carry on mate.

 

[JohnW2]

But since you seem to use jb's in inaccessible places ....

Whilst I agree with the spirit of the rest of what you say, where did that comment come from? - the OP merely asked what maintenance-free JBs were, and where they should be used (and wondering whether it would be better to use them, even in accessible locations), and I didn't see any reference to what (s)he does (or does not do) as regards JBs?

... and, yes, I'm still here, albeit to a reduced extent!

Kind Regards, John.

 

[seasickstevie]

...don't have to use inaccessible junction boxes and if you cannot then consider alternatives such as crimping or accessible junction boxes.

The way I read it, I don't think the OP is necessarily intending to put JBs in inaccessible places. On the contrary, he seems to be asking, when a JB is used (and in the real world they are!), should it be "best practice to use MF ones?"
Seems like a good question to me.

But then some seem to think JBs should be outlawed.

(Nice to see you're still around John)

 

[AndyPRK]

Would is almost be best practice to always use a Maintenance Free junction box for peace of mind, as I assume it provides more robust connections?

No.

Interesting responses everyone, Andy could you expand on your answer as to why?

Normal junction boxes with screws have been used for decades and are proven over that time.

Maintenance free JB are just a loop hole to get around the regulations, and I assume are little more than cheap bits of springy metal. They haven't been proven over time, they maybe better but it is a little early to know.

 

[17thman]

of course junction boxes should not be "outlawed". they are a legitimate way of joining conductors in circumstances where they are useful.

I consider, that under floor boards, even with markings on the boards is still inaccesible as you would need to be lucky or psycic to lift the correct carpet.

What is wrong with crimps and a good enclosure?

 

[ericmark]

I first came across the spring clip maintenance free connector strips in German equipment and they were a real pain to wire without using pin crimps but I could see the point as often when the maintenance program required the screw terminals to be checked on a regular basis like with batching plants which due to vibration were plagued with terminals coming lose the cables would often end up being cut by the screw and failing anyway.

However in a house there is unlikely to be a maintenance program and one would be lucky if the terminals were even checked on the 10 yearly electrical condition report.

My daughters house we assume had the consumer unit moved when the garage was turned into a room and we will guess somewhere there is a large junction box joining all the cables buried in a wall some where. The problem is we don't know where it is. This is the main problem with most houses there was very little paperwork raised when alterations were done and even when it was done finding it is another problem.

It does not really matter what type of joint is made there is a chance something will one day go wrong so does not matter if it's a cable buried under the ground or in a wall one wants some record of where the joint is so if it does go wrong one can find it.

Clearly we hope a crimped joint in shrink sleeve or epoxy resin under the ground will not fail but from time to time they do. So yes I would if cost not too high replace whole cable rather than join it. Some times however there is no option. Main reason for joining is cable damage so to use crimps often one has to use two joints and add a short lenght of cable. The JB will often give one just enough extra lenght so one can use a single joint. But room is also an issue. Although the epoxy resin joint is better in many ways to the epoxy coated shrink sleeve the latter is slimmer and so in some cases one has to use the shrink sleeve type. The repair in a wall may also require a slim repair and again one has to select the most appropriate method.

So the maintenance free spring clip connector does have it's place. And they have been used for many years now. Around 1992 I started to see them coming in so I expect at least 20 years and I have to agree in large panels as used with batching plants they did work well. The only problem was removing wires as I have seen a few damaged where people have tried to remove the cables. They have been used with ballasts in florescent lights for even longer around 40 years.

With large machines crushing plants, batching plants and the like I have often found lose connections with screw terminals where the steel structure has vibrated. But I can't say I have had the same experience in domestic premises in the main where terminals have been lose it's more likely due to a screw binding possible due to stray strand rather than becoming lose after. I have never seen pin crimps used in house wiring and so where any flex is used there is always a chance of a screw binding.

So yes I would use the spring clip connector block not because I think the screws will come lose in other type but because less chance of them not being tight in the first place.

As to the twist connectors used them in many years ago but not impressed. Working with Dutch systems we had little grey 4 wire connectors back in 1980 working in Algeria with spring clip retention these were used a lot in junction boxes and did not see many fail. However there was no release hole so like those used with florescent fittings it was a pain to try and re-use.

But the spring connector has stood the test of time so can't see how we can argue against them.

 

[mikhailfaradayski]

Would is almost be best practice to always use a Maintenance Free junction box for peace of mind, as I assume it provides more robust connections?

No.

Interesting responses everyone, Andy could you expand on your answer as to why?

Normal junction boxes with screws have been used for decades and are proven over that time.

Sorry Andy, but i have to disagree with that. I have found problems with screw connections, either loose and causing flickering or random faults and even where the installer has gone too hard with the screwdriver and the (usually 1mm) cable has necked off adjacent to the terminal.

Maintenance free JB are just a loop hole to get around the regulations, and I assume are little more than cheap bits of springy metal. They haven't been proven over time, they maybe better but it is a little early to know.

Sorry to disagree again, but as others have already mentioned, spring terminals have been around in one form or another for a few years (perhaps more notably on machinery, subject to movement/vibration) and seem to be the product of choice for a number of machine manufacturers.

 

[JohnW2]

Sorry to disagree again, but as others have already mentioned, spring terminals have been around in one form or another for a few years (perhaps more notably on machinery, subject to movement/vibration) and seem to be the product of choice for a number of machine manufacturers.

I don't think anyone has ever disagreed (and I doubt many would disagree) that spring terminals offer a distinct advantage over screwed ones in high vibration environments.

Kind Regards, John.

 

[mikhailfaradayski]

Sorry to disagree again, but as others have already mentioned, spring terminals have been around in one form or another for a few years (perhaps more notably on machinery, subject to movement/vibration) and seem to be the product of choice for a number of machine manufacturers.

I don't think anyone has ever disagreed (and I doubt many would disagree) that spring terminals offer a distinct advantage over screwed ones in high vibration environments.

Kind Regards, John.

Hi John,

Not sure why you quoted me here, but just to clarify, is you comment in support of my comment or a disagreement with it?

 

[JohnW2]

Not sure why you quoted me here, but just to clarify, is you comment in support of my comment or a disagreement with it?

I quoted you because you were the one who wrote it! As stated, it's supporting the use spring terminals in high vibration environments but was meant to suggest that this special situation doesn't necessarily translate to superiority in other situations.

Kind Regards, John.