Difference between "Single pole with switched neutral" AND "Double Pole" ?

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Please clarify:

What event is an example where a '

Agree with Running Piglet. I'm not sure if things have changed but it used to be that an SP+N breaker will break last and make first the neutral and has no overload protection on the neutral pole. A 2-pole breaker obviously both poles feature mag and thermal overload and no particular order to the making and breaking of the poles. I only know for a fact in the old Heinemann MCB's the SP+N version had equally sized contacts on both poles but it wouldn't surprise me if modern versions had a smaller neutral contact in the interest of saving a tenth of a gram of brass.
Yeah, making the N contact smaller and slower doesn't just save brass it saves a lot of the arc blowout space too!
 
Please clarify:

What event is an example where a 'double pole' device and a 'SP+N' device would act differently?
double pole MCB's are mainly used in industrial setting's for two phase supply's and single pole+ N are mainly use in domestic setting's, on a single phase supply they will do the same job, but so would a Three pole one, why would you use one? I don't think they make a 2 pole RCBO's, I am sure they only make only single pole +N ones, so not doing the same job ,i.e.. no earth leakage protection with a double pole MCB,
 
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would a Three pole one, why would you use one? I don't think they make a 2 pole RCBO's, I am sure they only make only single pole +N ones, so not
This one dates from 2001 so they did used to exist …
 

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There are loads of single module RCBO options now switching both poles, including Fusebox RTAM range above, but these are considered SP+N as they don't have overcurrent protection on the neutral.

Ready to stand corrected, but I think the 2 module RCBOs used in many countries do have overcurrent protection on both poles.
 
Actually I see from my photo the diagram on the RCBO shows overcurrent trip only on in the phase line. So I guess that means it would be SP+N - or did you mean you did not know of 2 module width devices ?
yes two pole not two module, I did know of the two module units , at a time that was all you could get, but I am glad that someone is watching me
 
There are loads of single module RCBO options now switching both poles, including Fusebox RTAM range above, but these are considered SP+N as they don't have overcurrent protection on the neutral.

Ready to stand corrected, but I think the 2 module RCBOs used in many countries do have overcurrent protection on both poles.
you could be right this one looks like its got O/L on both poles, I have must have seen them but really looked at them close
 

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you could be right this one looks like its got O/L on both poles, I have must have seen them but really looked at them close
It's not really the sort of thing I ever paid attention to, until I asked myself why RCBOs were being classed as SP+N as opposed to DP. Until then I'd called them all DP.
 
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