2391 exam questions

[brucelee]

please can someone advise, couple of questions thats mixing me up

1. state the purpose of initial verification of a newly installed lighting circuit
exam success says
. to confirm the circuit complies with designers intentions
. the circuit has been designed, installed and tested with the requirmements of bs7671
. it is not damaged so as to impair safety or otherwise defective
the booklet college gave us says
. materials of the correct type to comply with BS
. Erected and selected properly
. no damage or defects are present
what do you reckon guys

2. state the purpose of a periodic inspection and test of an electrical installation as defined in bs7671
exam success says
. To establish wether the installation is in a safe condition for continued service
the booklet from college says
. safety of persons and livestock
. protection against fire
. no damage
. identify defects and non-compliances
which do you reckon is right to answer
last one

3.a) state in the correct sequence, the first three tests to be carried out on a new ring final circuit
exam success says
. continuity of protective conductors
. continuity of ring final circuits
. insulation resistance
or alternative
b). contniuity of ring final circuit conductors conductors
. insulation resistance
. earth fault loop impedence
but when tutor gave us sample tests same as exam success he wrote CE report says
c).continuity of ring final circuit conductors
. insulation resistance
. live polarity

 

[pushrod]

please can someone advise, couple of questions thats mixing me up

1. state the purpose of initial verification of a newly installed lighting circuit
exam success says
. to confirm the circuit complies with designers intentions
. the circuit has been designed, installed and tested with the requirmements of bs7671
. it is not damaged so as to impair safety or otherwise defective
the booklet college gave us says
. materials of the correct type to comply with BS
. Erected and selected properly
. no damage or defects are present
what do you reckon guys

2. state the purpose of a periodic inspection and test of an electrical installation as defined in bs7671
exam success says
. To establish wether the installation is in a safe condition for continued service
the booklet from college says
. safety of persons and livestock
. protection against fire
. no damage
. identify defects and non-compliances
which do you reckon is right to answer
last one

3.a) state in the correct sequence, the first three tests to be carried out on a new ring final circuit
exam success says
. continuity of protective conductors
. continuity of ring final circuits
. insulation resistance
or alternative
b). contniuity of ring final circuit conductors conductors
. insulation resistance
. earth fault loop impedence
but when tutor gave us sample tests same as exam success he wrote CE report says
c).continuity of ring final circuit conductors
. insulation resistance
. live polarity

With 1) i don't see a great deal of difference - maybe first answer college success just shading it

With 2) more detail in the college booklet - certainly bs 7671 alwaays bangs on about safety of persons and livestock so i would go with that one

With 3) answer c is definitely not right . A is is good, often written as1. continuity of conductors (to include i)protective conductors inc main and supplementary bonding and ii)ring final conductors 2.insulation resistance 3.polarity. Don't think B is good either- EFLI is definitely not in first three.

 

[Risteard]

With 3) answer c is definitely not right

Why not? Dead polarity has already been confirmed through continuity of ring final circuit conductors.

 

[Risteard]

Actually, I prefer Exam Success' answer on the basis that live polarity is not carried out on the circuit but the incoming supply.

 

[iceman]

for initial varification ya answer should be
no part of the fix installation is not damaged or otherwise defective
all parts of the fixed installation is correctly selected and erected
all installed electrical equiptment and marial is of the correct type and complies with british standards

ring final continuity should be

continuity of ring final circuits conductors
insulation resistence
polarity but this has already been confirmed wile doin continuity but there looking for this answer

 

[brucelee]

for initial varification ya answer should be
no part of the fix installation is not damaged or otherwise defective
all parts of the fixed installation is correctly selected and erected
all installed electrical equiptment and marial is of the correct type and complies with british standards

ring final continuity should be

continuity of ring final circuits conductors
insulation resistence
polarity but this has already been confirmed wile doin continuity but there looking for this answer

in exam success it says
1. continuity of protective conductors
continuity of ring final circuits
insulation resistance
or
2.continuity of ring final circuit conductors
insulation resistance
earth fault loop impedence
and then says this is acceptable because this cofirms continuity of protective conductors and polarity is carried out by the test
then our tutor at college gave us copies of the two tests with answers and for this he says the second of the above is wrong according to Cheif examinors report and he has wrote polarity in e.g.
. continuity of ring final circuits
. insulation resistance
. polarity
but he didnt say if the first of the above is ok i have emailed him as the course is finished but i do my written exam on the 10th of june and practical assessment on the 15th gettig nervous now i have afew more that are contrdictory like above
as follows
1.State two methods of carrying out a polarity test on a radial socket outlet circuit before energising
Exam success says
. using the R1+R2 test
. The use of a long lead
our tutor at college says
what about line cpc reversal
but again gave us no alternatives he says he will respond to my email tomorrow when he has more time but if anybody else knows i would be grateful dont need all this extra confusion as my test is approaching
state the difference in the earth electrode resistances for electrodes used to provide an earth for
i) supply transformers
ii) a TT installation protected by an rcd
answer according to Exam success
i) should not exceed 20ohms
ii) recommended below 200ohms
i)in On site guide it says 21ohms at supply and this is what the tutor says
So considering i paid £20 for a book i thought had correct questions and answers similar to what i would be expecting in the exam there are a lot of errors so if anyone can set the record straight please

 

[pushrod]

Why not? Dead polarity has already been confirmed through continuity of ring final circuit conductors.

just about to explain why when i realised that it does actually say a "a new ring final circuit" in the question - i had initially read it as just " new circuits" and so was about to say no mention of continuity of protective conductors - apolgies

I took my 2380 exam tonight - at least i was paying a bit more attention there . Scored 57 out of 60

 

[pushrod]

1.State two methods of carrying out a polarity test on a radial socket outlet circuit before energising
Exam success says
. using the R1+R2 test
. The use of a long lead
our tutor at college says
what about line cpc reversal
but again gave us no alternatives he says he will respond to my email tomorrow when he has more time but if anybody else knows i would be grateful dont need all this extra confusion as my test is approaching

1) wandering lead

2) join R1 and N at Consumer unit test continuity at sockets with adaptor (leads in bottom two positions)- this confirms L and N in two bottom positions at each socket but not that they are in the correct position.
However if you then join R1 and cpc (R2) at CU and test with adaptor again at each socket and you again get continuity (with leads in top and right position) this proves polarity as the line must have been in the correct position to get continuity the 2nd time. You can't have a line - cpc reversal because you wouldn't have got continuity the first time.(you proved that Line and neutral were in the bottom two positions - the cpc must have been correct!

 

[Risteard]

just about to explain why when i realised that it does actually say a "a new ring final circuit" in the question - i had initially read it as just " new circuits" and so was about to say no mention of continuity of protective conductors - apolgies

I took my 2380 exam tonight - at least i was paying a bit more attention there . Scored 57 out of 60

No probs. It's easy to miss things when reading them.

I've been trying to read books for 2391-20 and keep skipping over important information. I think my brain's turned to mush!

 

[brucelee]

Thanks to you all for the help could you have a look at the following

for surge protective devices is it the usual tests of between lives (L-N), then between lives and earth (L-E and N-E) at 250v d.c. min bs7671 value 1.0Mohm

For selv to lv is it
between lives of selv connected together and lives of the LV circuit connected together at 500v d.c. 1.0Mohm min

between lives of selv connected together and the protective conductor of the LV circuit and any exposed conductive parts in the same area as the selv at 500v d.c. 1.0mohm min

For selv is it between L-N of the selv at 250v d.c 0.5Mohm and
lives of selv and any exposed conductive parts at 250v 0.5 Mohm min value
cheers for help

 

[pushrod]

Thanks to you all for the help could you have a look at the following

for surge protective devices is it the usual tests of between lives (L-N), then between lives and earth (L-E and N-E) at 250v d.c. min bs7671 value 1.0Mohm Yes although it is commonn to disconnect surge protection devices if it is easy to do so and test at 500v, but as you have said above if you leave them in.

For selv to lv is it
between lives of selv connected together and lives of the LV circuit connected together at 500v d.c. 1.0Mohm min yes

between lives of selv connected together and the protective conductor of the LV circuit and any exposed conductive parts in the same area as the selv at 500v d.c. 1.0mohm min
TBH i didn't even know you do that i know you do between lives of selv( or pelv) and live parts of other circuits at 500V


For selv is it between L-N of the selv at 250v d.c 0.5Mohm yes and
lives of selv and any exposed conductive parts at 250v 0.5 Mohm min value don't know -thought there wouldn't even be any exposed conductive parts on a selv circuit??
cheers for help

There are bits about IR testing for selv and pelv in the OSG pages 83,84 and 85 if you haven't already seen them. Did you understand the second method of testing polarity above - wasn't sure how clearly i explained it.

 

[brucelee]

There are bits about IR testing for selv and pelv in the OSG pages 83,84 and 85 if you haven't already seen them. Did you understand the second method of testing polarity above - wasn't sure how clearly i explained it.

Two methods to do a polarity test on a radial socket outlet
1). Is it by continuity method 1 first link L-CPC test at each socket between L and Cpc. then repeat but with Line and Neutral linked at db and test between L-N at each socket
2). or use wander lead and method 2 as for ie R2 testing line in correct position and then N and then CPC
is that right is this how i would word it for exam
My tutor has just replied so i will see if we was right
thanks for your help
I am just practicing writing test procedures and trying to work out when to include using a approved voltage indicator
Will the question state wether or not this is required

we are right for the surge protective devices as above
and for the selv in same area enclosure this is also right