I've been mulling over how to connect a largish number of pumps/motorised valves/thermostats etc (many with manufactured with a short length of flex) to fixed wiring, where I don't have a lot of wall space for adapable boxes/flex outlets - and briefly considered using a length of 50x50 PVC trunking, stuffing glands and push-terminals inside.

I initially rejected that as the connections would be accessible without the 'use of a tool or key' (as the lid of the trunking can be prised off with fingernails), but then got to thinking about a lot of the new plastic JB boxes which have 'snap-on' lids (e.g. http://www.tlc-direct.co.uk/Products/WK108G.html ). Presumably these count as being openable without the use of a tool or key? (I'm sure I've been able to prise a few different makes open with just fingers, although some certainly need a bit of persuasion with a blade of some sort.) Does anyone know what the official status is of these boxes - openable without a tool/key or not?

I then had a read of 412.2.2.3 and realised that that removing the cover without a tool wasn't a problem provided the innards were IP2X (or IPXXB) and that protection wasn't removable without the use of a key/tool. Modern, plastic housed terminal strips (choc block terminals) probably are IP2X, so is that the get-out for the clip-on lid boxes?

But that then begs the question about push-terminals. Normally the wire can be removed without a tool (either by squeezing the terminal in the case of the flex-connection types, opening a lever, or pulling and twisting the wire) - so live conductor end could me made accessible (worse than IP2X) without using a tool or key. So effectively, is there a ban on using push-terminal in boxes (or PVC trunking) with clip-on lids?

- Andy.

I have been accustomed to providing plugs/sockets in these situations. Where SCADA etc. is employed, it's easier to fault find by swapping out or even shorting out.

Regards

Effectively, yes Andy - although without doubt, this is an area where new technology and practice has fallen foul of long standing regulations.

I'm not sure how many terminals you are trying to deal with but a rectangular box with din rail terminal blocks can accomodate quite a few - I've also used a number of dual boxes with blank plates and wagos to achieve what you want to do in the trunking.

If you do use trunking - a top hat section over the trunking and screwed to the wall defats anyone popping the lid off ?

Regards

OMS

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Failure is always an option

Well this is it, ive yet to use one, but if you can put junctions into a junction box with a snaptop lid what can you put in there?

It depends on the terminal or connector you use - wagos for example would allow direct access to live terminals without a key or tool - a bog standard chock block may well actually meet the IP rating of IP2X - din rail equipment would probably meet the same or better IP rating - you could also have an inner shroud that needs a key or tool to remove.

Any electrical enclosure containing terminations with a "snap on" lid has to be suspect anyway doesn't it ?

Regards

OMS

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Failure is always an option

Thanks lads!


That's a good & interesting thought. What sort of plugs/sockets do you usually use? (I'm thinking of the motorized values with 4 or 5 poles +PE)


Off the top of my head, 4 pumps, 5 thermostats, 4 motorised valves, a flow switch and around 8 zone actuators. The awkward bit is that they're scattered around a thermal store, so that there's no one point where all the various flexes will reach to (or even close) - and courtesy of some post-initial-planning changes, not a lot of accessible wall space for lots of wall boxes - hence the idea of one length trunking running floor-to-ceiling - one very long thin adaptable box being the idea.


Now why didn't I think of that?!

I did consider using steel trunking, so getting screw fixing for the cover that way, but I'm sure I'll end up wanting to alter something or other in the years to come, so have to cut extra holes - and the idea of swarf dropping down the vertical run unnoticed into a terminal didn't appeal.


I think typical screw terminal blocks are OK - the question was with the "tool-less" push-wire ones (wagos etc), as technically the conductor can be exposed without using a tool or key.

cheers

- Andy.

OK Andy - vertical 50 x 50 trunking (PVC) or a spare bit of 50 x 100 dado, bag of wago's, bag of stuffing glands and a bit of all round band to secure the lid and away you go. I guess as space is at a premium, can you get all those multiploe plug and sockets to fit

And given it's for the energy centre at Maison Jewsbury, is it credible that someone will pull off the lid and fiddle - I guess not, so dispense with the all round band.

I wouldn't use metal trunking personally.

Regards

OMS

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Failure is always an option

Have you tried opening a populated, closed
Wago box with hands only? (I have not got a vested interest).

Regards

If you did want to use wiska boxes they do the type with a screw lid as well.

http://www.tlc-direct.co.uk/Im...ucts/size_3/WK308B.JPG

Thanks OMS.


I've not tried the wago box, but some others I have opened by hand, others have needed prising with a pocket knife blade - hence the question about their official status. Thinking about it, it's probably better phrased as a 'clip off lid' rather than 'clip on lid' question.


Cheers - yes, they're the ones I usually use. It was just the comparison with PVC trunking that led me down that path.

- Andy.

Andy,

You could change all the stats & actuators to wireless "en ocean" 32 cores gone

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Regards

Martyn.

Only a mediocre person is always at their best



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