June 2011 2391 exam

[Richard]

Did any of you sit it? I didn't think it was TOO bad, couple of questions I was a little unsure of but overall ok. How did you guys find it? I can never think of the bloddy questions afterwards!

 

[joe_berks]

appendix 12 of 7671 for the 8% figure.

 

[joe_berks]

oh no it was 5% ! starting to really doubt myself now thought i had it in the bag .

 

[luke]

Just sat the exam myself, found it ok really, first time so fingers crossed. The question on the rcd is 1/2 x test 50mA and 1 x test 100mA 300ms. The only rcd you test at 5x test current is a 30mA rcd otherwise you put to much current into the installation. Is the pass rate 60 % ?

 

[dean7828]

im sure 5x test applies to a 30ma rcd for additional protection and must operate within 40ms

 

[dean7828]

i well got some right got some wrong just hope its enough! not the end of the world if not good luck chaps

 

[joe_berks]

can anyone else remember more questions from the exam ? i left with quite a bit of time to spare feeling confident but have already found out i got a couple wrong !

 

[Jurasic Spark]

Just sat the exam myself, found it ok really, first time so fingers crossed. The question on the rcd is 1/2 x test 50mA and 1 x test 100mA 300ms. The only rcd you test at 5x test current is a 30mA rcd otherwise you put to much current into the installation.

Correct... but not the right reason.

415.1 x5 only where RCD is used for Additional protection. By definition this is an RCD not exceeding 30mA but could be one lower such as a 10mA RCD.

 

[honda127]

Where do you get the 8% voltage drop for three phase figure from? I'm stuggling to find that one

im sure its 5% FOR POWER AND 3% FOR LIGHTING

 

[honda127]

Dnt be worrying too much lads it will do your head in , i was so sure i failed i paid to sit this exam but got my results from march one and i passed.Really i felt i made a total bullocks of it

 

[sharpy1983]

The tests for a 100mA RCD are still 1x and 5x. and the maximum disconnection for this type of RCD is 300ms, Glad this come up as we were discussing it only yesterday!!!

I thought it was ok. some questions I guessed but most I was pretty confident on. plus questions 21-26 didnt seem as bad as some others Ive seen on past test papers.

 

[sharpy1983]

I thought the voltage drop question was 3% for lighting and 5 for power too

 

[sparks_114]

I too just sat the exam, question no 19 (the one after the 100mA RCD question) is the one that threw me with the short circuit capacity of an circuit breaker. I had no idea of the difference between Icn at 6KA and Ics at 10KA and the question being what would happen if a fault current (PSCC I believe) of 8 KA were to exist? I asked a good few others after and likewise no one seen to know. Overall I did think it easy (ish) for a 2391er but only the hard results will tell. All the best to you fellas.

 

[brucelee]

good luck to all now the wait begins

dont worry if there are only 1 or 2 questions that your not sure off then you have probably done enough

 

[luke12345]

I too just sat the exam, question no 19 (the one after the 100mA RCD question) is the one that threw me with the short circuit capacity of an circuit breaker. I had no idea of the difference between Icn at 6KA and Ics at 10KA and the question being what would happen if a fault current (PSCC I believe) of 8 KA were to exist? I asked a good few others after and likewise no one seen to know. Overall I did think it easy (ish) for a 2391er but only the hard results will tell. All the best to you fellas.

Icn is the max PFC that the be interrupted safely but the breaker will no longer work
Ics is the max PFC that can interrupt safely without loss of performance

think you've mixed them up in the question, so basically 8KA would knacker the circuit breaker

 

[NEV]

Sat the exam had a complete brain meltdown, the paper was a lot easier than other ones i read however i just couldn't think. Hopefully i did enough? 9 weeks to wait