I might well have to take that approach - maybe just re-housing the switch from one like that. Any idea how big the switch in one of those things is (it might be almost as large as the enclosure!)?
Kind Regards, John
Changeover Switch
- Thread starter russellsmiler
- Start date
Kind Regards, John
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It's in an enclosure of that size for a reason - the enclosure size affects the Ith rating, as well as whether or not suitable bables can be terminated.
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Maybe - but I rather suspect that the enclosure of the 32A one is pretty OTT in terms of either Ith or any size of 'bables' likely to be used with a 32A switch. In any event, for the use I'm thinking about, my requirement would be far modest than even 32A, with 2.5 mm² cable at greatest (quite probably 1.5 mm²), so I'm sure that a small switch in a small enclosure would be fine. In fact, I'm tempted to just use a standard 10A DPDT centre-off toggle switch.
Kind Regards, John
Fair enough, but not everyone who reads this thread will be capable of making that judgement.
Sorry, as you've guessed I meant 'cables'. It's been a long day!
What are you trying do do John?
Sooner or later I'll be buying one of those Lewden DIN rail ones - I'll take a photo of the inside of that enormous metal box for y'all.
True. I do, however, wonder about the need for as large enclosure and enclosure as we are talking about (190 x 110 x 100 mm = 2090 cm³), even when used at full rated (32A) capacity. Let's face it, I can buy a (MK) 32A DP switch attached to a single 40mm surface box, rated to take 10 mm² cables in that configuration (86 x 86 x 40 mm = ~296 cm³). I can't see why 'moving up' from that to DPDT (with 2 further cables) should result in the need for a very much (about 7-fold) larger enclosure (and nor do I really see why one would ever want to use 10 mm cable in a circuit which included a 32A switch).
No problem! As must be the apparent, I'm the very last person who is in a position to be critical about typos!
It's currently just some 'embryonic idle thoughts' going around in my mind - re-ignighted by seeing this thread about changeover switches!
Kind Regards, John
Fair enough. However, that's a 125A switch and, in particular, is rated for cables up to 50mm². Doing anything with 50mm² conductors undoubledly does require an 'enormous metal box' in which to work (and skills more associated with plumbers than electricians
). I can but presume that you will be using much more modest cable than that, and therefore could manage with a far smaller enclosure.Kind Regards, John.
One reason might be that the switch can't carry 32 A continuously unless connected to a substantial cable to act as a heat sink.
That surely would be delinquent product design.
You can legitimately have a B32 protecting a 4mm² radial supplying BS 1363 socket outlets. Are you suggesting that there might be other 32A accessories available which would overheat on that circuit?
You can legitimately have a B32 protecting a 4mm² radial supplying BS 1363 socket outlets. Are you suggesting that there might be other 32A accessories available which would overheat on that circuit?
What I'm suggesting (actually more than a suggestion) is that the product standards require that the conductor size connected during testing is stated in the test report, since it has a bearing on the device's ability to carry current.
Yes, reliance on a larger conductor than might be used in practice is delinquent/incompetent/dishonest product design. There's a lot of it about, largely since people tend to buy the lowest cost devices that they think will do the job.
Yes, reliance on a larger conductor than might be used in practice is delinquent/incompetent/dishonest product design. There's a lot of it about, largely since people tend to buy the lowest cost devices that they think will do the job.
I can't work out to what extent your tongue was in you cheek when you wroite this. My comment was, as you know, nothing to do with switch specs/ratings but, rather, a response to the second part of your comment "It's in an enclosure of that size for a reason - the enclosure size affects the Ith rating, as well as whether or not suitable bables can be terminated."
... and I took that second part to be a reference to the fact that very large conductors might need substantial space in which to be 'managed' and terminatied. My point, therefore, was that I could see no real reason why a circuit containing a 32A switch would involve cable even as large as 10mm², let alone larger - hence that large amounts of space to manage that cable would not be required.
I would also suggest that if a fairly modestly-rated switch generates enough heat to require external heat-sinking, that then there is surely something very wrong with that switch. I would certainly hope that there would be no significant temperature rise in a 32A switch carrying 32A, even without any significant external heat-sinking. In any event, as BAS has been pointed out, it would be both ludicrous and irresponsible for anyone to offer for sale a "32A switch" which, if carrying 32A, was only safe if connected to conductors of at least 10mm² CSA!
Kind Regards, John
It often surprises me that people will disparage references to, for example, "32 amp cable" since the cable's current carrying capacity depends on the installation method, but are quite happy to talk about a "32 amp switch" as if it has a rating that does not depend on the duty cycle, installation, or utilisation category.
Given the context (a DIY forum, hence primarily domestic, and certainly not industrial), I'm not at all surprised by that, but I am rather surprised that you're surprised!It often surprises me that people will disparage references to, for example, "32 amp cable" since the cable's current carrying capacity depends on the installation method, but are quite happy to talk about a "32 amp switch" as if it has a rating that does not depend on the duty cycle, installation, or utilisation category.
The situation with cable is clear-cut, in domestic installations the same as anywhere else. All electricians hopefully know, and anyone installing cables should know, that the current carrying capacity of a given cable varies appreciably between a fair range of installation methods which are encountered in domestic installations. Furthermore this topic is covered in considerable detail in regulations, guides, books, on-line resources and training courses.
In contrast, neither instructions/standard documentation associated with accessories designed for domestic use nor any of the usual reference documents or (AFAIK) training make any mention of the need to consider any dependence of accessory current ratings on any factors (usage, installation method etc.) other than, perhaps, extremes of ambient temperature. The assumption (yes, I know! - so perhaps I should say 'implication'!!) is therefore that the stated/marked current ratings of accessories remain applicable in even the 'worst case' usage/installation situations likely to be encountered in a domestic (or many commercial) installation.
Do you really disagree with that? Taking the example of a switch, do you really think that there are (domestic) situations (other than, perhaps, unusually extreme ambient temperatures) in which an electrician should consider the possibility that a switch's current-handling capacity may be less than its "rated/marked" value?
Kind Regards, John.
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