Consumer units - Contactum in particular

I'm looking for a consumer unit to use for the 12 volt DC switchboard in our boat. While I'm pretty sure *any* MCBs will actually work at 12 volts I'm aiming to use a make which actually specifies that 12 volts is OK.
The available makes I have found so far which say 12 volts is OK are:- Contactum Square-D Hager MEM Proteus
The Electrium family (Wylex, Crabtree, Volex and a lot of wholesaler own-brands) only say down to 24 volts. MK doesn't specify DC at all.
So my front runners at the moment are Contactum (very good prices from TLC at the moment) and Square-D (from Toolstation probably). At the moment I'm leaning towards a Contactum metal consumer unit.
Does anyone have any recommendations (or otherwise) for any of these brands?
--
Chris Green


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On 20/07/2010 12:32, snipped-for-privacy@isbd.co.uk wrote:

I have used quite a bit of the contactum stuff - although more often the plastic rather than metal clad enclosures. On the plus side, its cheap, has plenty of space and is easy to work on. The plastic is quite soft - which is not a bad thing - it cuts easily enough without shattering. The unused way blanking plugs are just caps that plug into the gap rather than the more elaborate dummy MCB type approach used by hager and MK etc. The range of devices they produce is not as wide as hager or MK (although the latter will usually fit the contactum boxes!)
Of the others Hager are pretty good all round IME, MK also but pricey. MEM tend to be more focused on the commercial sector and their stuff can tend to be a little less "standard", but the quality is usually very good.
Proteus seem to be gaining popularity and acting as OEMs for a number of other brands, but I have had some rather unpleasant experiences with some of their kit (notably MCBs that only electrically turn on one time in three when you mechanically turn them "on" - that can make fault finding harder than it ought to be!)
--
Cheers,

John.

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OK, thanks, gap plugs are relatively unimportant at 12 volts. Also I agree about the smaller range of accessories but I don't think I need any and, as you say, other makes will fit.

MK are ruled out by not saying they work at 12 volts in their specification, they probably do work but with MCBs that are specified to work at 12 volts I have some comeback if things don't work as they should.

OK, so probably won't choose Proteus then, I can't find a reasonably priced supplier anyway!
--
Chris Green


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On 20/07/2010 15:00, snipped-for-privacy@isbd.co.uk wrote:

I have used three contactum CUs on my place (all plastic - we are TT here), and generally I quite like them. I needed to fit MK type S RCDs, and a Hager HRC fuse carrier. The only slight annoyance is they subtly changed their design recently and the old an new MCB are not quite a perfect interchange (you can force wm because the box is soft enough!) However if buying now that is unlikely to be a problem for you.
--
Cheers,

John.

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On 2010-07-20 14:42:05 +0100, John Rumm said:

I have also had problems with Proteus MCBs.
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This is 12V, so you need reliable disconnection.
Schneider used to make Merlin-Gerin, Square-D & MK brands. MEM are well regarded.
So I would go with whichever is cheapest.
Might be worth calling their tech helplines to see if any "application notes" re 12V operation.
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On Tue, 20 Jul 2010 12:32:59 +0100, tinnews wrote:

They specify down to 24 volts because of the contact material. It is designed for mains switching and there may be insufficient voltage below 24v to break through the thin film of oxide that can form on the contacts while open for any extended period of time. Note that if the contacts are closed the oxide film isn't a problem and you can go down to lower voltages. That would normally be the case for a consumer unit.
Also, as I mentioned in a previous post, sometimes DC ratings on switchgear are only given *below* 30vDC or 48vDC because the contacts don't open far enough to break a DC arc from an inductive load at much above that! Makes it fun choosing DC switchgear...
GE Power Controls do a "proper" range of DC mcbs. EP100UC These are rated down to 12v.
ABB S200M are also rated down to 12vAC/DC.
There are some mcbs here: http://www.techna.biz/en/electrical/circuit_protection.htm that, although they don't give minimum voltage ratings, do show all sorts of information. This includes temperature compensation etc. Not often you find all the curves. I've not used their mcbs on jobs of any size, but they seem to be ok and were reasonably priced IIRC.
--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
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