When I bought mine they were cheaper again. I have been taking advantage of living in Ireland and making use of anticipating ( and buying) what I intend to use later.
will put this here instead of the “today I learned” thread (but mods welcome to move/nuke etc).
the terminology around mcb/breakers etc. can also do with a bit of standardization because
There appears to be 4 types of “MCB” which are only one module wide (about18mm) to which you can connect 2 “incoming” and 2 “outgoing” conductors. To the untrained and semi-educated like me, at first glance they all seem to fit the idea of “2 / double pole”. Other than the RCBO, the differences being basically
- a mcb where the live and neutral can be disconnected but only the Live can cause a trip on over current
- a mcb with two independent over current protected poles (over current in one pole will trip only that pole).
- a mcb with two interconnected poles (over current in either pole will trip both poles).
From a price perspective the 1P+N is about 60% of both 1P+1P/2P, and the latter is almost 50% of a similar RCBO.
Makes me curious, if budget is tight (for us plebs who are not lugging 4 checked bags through customs with “spare parts for my hearing aid” 
) whether there is any reason to take 2P over 1P+N, to achieve @Phil.g00 's suggestion? Also, any reason to avoid the 1P+1P in the same application scenario?
For this application, 1P+N would be perfectly fine, would it not? You still get the overcurrent protection on live, which you’d get with single-pole breakers too, but you additionally get isolation on the neutral to aid in fault finding. The upstream earth leakage ensures that live and neutral carries the same current too, which should also make overcurrent on just one side sufficient.
Edit: I don’t understand the 1P+1P breaker. Never seen one. Does it allow the lines to be switched individually? In that case, regulations say that if neutral is switched, it may not be single-pole, which would rule that one out.
is my thinking too, but don’t know whether there is that one special fault with Mars in retrograde during a bluemoon, where an “unprotected” neutral can burn down the house (not sure if a high resistance, i.e. loose connection on the MCB could be an issue - but proper work from the start and periodic checking should avoid that).
yes, and agree.
Something else I came across is that apparently on the 1P+N, the neutral contact breaks last and makes first, which might also make chasing faults interesting but for the application as mentioned it seems like the best option if needing to trim the budget.
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I have never come across a 1P+1P either. I assume there isn’t an electrical justification; it is just two single MCBs but with one footprint. So, it is just a space-saving feature, which may have its place in the market.
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My thoughts exactly. Could come in useful as well! How many of us had to redo DBs because we ran out of space?
On the other hand, crowded DBs are no fun either.