tonights 2391 exam....(10th march 2011)

[lynj]

one thing to say and that is did c&g forget how to be staightforward? felt like some of the questions were half thought......

anyone else take it?

 

[IQ Electrical]

I cannot see the value of creating scenarios with the intent of causing confusion. It is very easy to word questions in such a way as to direct people to the wrong conclusions, or put doubt in their mind, but who does that benefit. Exam conditions create a great deal of stress in most people so, in my opinion, clear and concise scenarios are far more likely to elicit a true insight into the knowledge of candidates than ones designed to throw you off track. I wonder how many people knew what a kiln actually is.

I don't think having a scenario is the problem-you're faced with a scenario every time you carry out inspection and testing.

The problem seems to be the ambiguity in the description of the scenario.

Again, without a 100% accurate posting of the scenario question, it's difficult to comment on answers and theories!

 

[Steve_Wilson]

I think the Q26 asked you to determine the operating current of the RCD for the circuit. I looked at the calculation but then discounted it as the resistance of the earth electrode was 100 ohm, therefore using the formula, the result was 500mA (for the main RCD). On top of that, you have to take into consideration the resistance of the circuit, therefore, that alters the calculation but as your not given the information to calculate out the resistance, I took it that they were seeing if you had read the senario where they stated the circuit was protected by a 61008/C 16a 30mA. I am probably trying to dig myself out of a hole with a teespoon but the way the whole exam seemed to be worded to me, it probably makes no difference. See you all in 12 weeks for the re-take. It can only get better.

 

[stu2009]

I think the Q26 asked you to determine the operating current of the RCD for the circuit. I looked at the calculation but then discounted it as the resistance of the earth electrode was 100 ohm, therefore using the formula, the result was 500mA (for the main RCD). On top of that, you have to talke into consideration the resistance of the circuit, therefore, that alters the calculation but as your not given the information to calculate out the resistance, I took it that they were seeing if you had read the senario where they stated the circuit was protected by a 61008/C 16a 30mA. I am probably trying to dig myself out of a hole with a teespoon but the way the whole exam seemed to be worded to me, it probably makes no difference. See you all in 12 weeks for the re-take. It can only get better.

You are correct on this. The scenario did state it was protected by a 30mA 61008 RCD. Also I'm sure question 24 asked how to measure earth electrode resistance directly which would require an earth electrode resistance tester(I think). Asked tutor on friday about the questions and he did confirm I was right on this(Very well known teacher and helped write a few books on testing, the doctor will know him). If the pass mark is 90-100 I think Ill pass anymore than that is going to be tight. Think I only dropped 5-10 marks on first section done Ok on the second section. All I can do is wait and hope like everyone else

 

[newby]

I was not objecting to scenarios in general, just those which are designed to muddy the water if you like. It's a trend which a lot of multi choice tests in a variety of subjects follow, and not the way to assess knowledge properly.

 

[stu2009]

Thats all the scenarios are there to do I think.

 

[Steve_Wilson]

Q24 asked for "direct measurement" of the earth electrode resistance so I took it that they wanted the measurement taking in the same way you would gain a Ze, diconnect earthing conductor so on. the more I watch this thread, the more I think everyone has a different take on the questions but like I said, we all know what we're doing in the field, it's just a case of proving it to the assessors. Good luck.

You are correct on this. The scenario did state it was protected by a 30mA 61008 RCD. Also I'm sure question 24 asked how to measure earth electrode resistance directly which would require an earth electrode resistance tester(I think). Asked tutor on friday about the questions and he did confirm I was right on this(Very well known teacher and helped write a few books on testing, the doctor will know him). If the pass mark is 90-100 I think Ill pass anymore than that is going to be tight. Think I only dropped 5-10 marks on first section done Ok on the second section. All I can do is wait and hope like everyone else

 

[BEDFORD ELECTIC]

Pm me for past pappers, and stuff ?
IF YOU CAN REMEMBER A 2391 MARCH 2011 MARINER QUESTION POST IT !

when conducting a insulation resistance test on the lamp post curcit, test between live conductors together and c.p.c.
its not practical to remove the contole gear
the photocell on top of the lamp-post must be coverd up to enable the onward wiring of the curcit to be included in the test.
( THE PHOTO CELL---- ACTS AS A LIGHT SWITCH----- all ways include the strapper wires ect ect )
500v dc


Q) discribe how you would conduct a insulation resistance test on a curcit that has SURGE PROTECTION ?

A) test at 500v dc as normal
(BS7671 443.2) surge protection is basicly a bolt of lightning hitting part of the installation.

Q) name 3 locations witch have zones

A) location containig a bath or shower / sauna / swimming pool / water fountain

Q) how do you test the rcd (8 marks)

A) 50% --- 15ma---no trip
100%---30ma--- within 200ms
500%---150ma within 40ms

Q) when the new circit is connected, what will happen to the insulation resistance value, for the whole installation ?

A) the value will decreass

Q) why can you not do Zs-Ze to get the value for R1+R2

A) Ze may containe parralel paths

Q) why dose BS7671 state the mariner cannot be a T.N.C.S system

A) the dangers of water and electric / lower body resestiverty / contact of the body with earth potential.

Q) visual inspection in the shower block c.c.u, list 4 thing to look for (4 marks)

A) external influances
basic protection
correctly selected and erected
any visibal damage
Q) what in the above are you looking for (4 marks)

A) is there warter / dust ???
can some one touch live parts ???
in acordance with BS7671 ???
damage / ware and tear


Q) name 2 bits of infomation, that can only be obtaind via the supply authority.

A) ????? ????????? ????????? ???????? ????????????? ?????????????? ??????????

Q)name the 2 people who can decide the time for a periodic Inspection Report.

A) the designer / the tester

Q) work out the values for R1+R2 (3 marks)

A)0.96+127
-------- = 188
4
Q) name 3 things that may afect the next PIR date (3marks)

A) external influances
type of installation
maintenace shedual
Q) what is the maximum voltage drop for...
lighting ?
power ?
motor ?
A)3 %
3 %
3 % ( see page 358 in Bs7671)
............................Pm me for past pappers, and stuff ?...............................................

 

[BEDFORD ELECTIC]

Pm me for past pappers, and stuff ?
IF YOU CAN REMEMBER A 2391 MARCH 2011 MARINER QUESTION POST IT !

when conducting a insulation resistance test on the lamp post curcit, test between live conductors together and c.p.c.
its not practical to remove the contole gear
the photocell on top of the lamp-post must be coverd up to enable the onward wiring of the curcit to be included in the test.
( THE PHOTO CELL---- ACTS AS A LIGHT SWITCH----- all ways include the strapper wires ect ect )
500v dc


Q) discribe how you would conduct a insulation resistance test on a curcit that has SURGE PROTECTION ?

A) test at 500v dc as normal
(BS7671 443.2) surge protection is basicly a bolt of lightning hitting part of the installation.

Q) name 3 locations witch have zones

A) location containig a bath or shower / sauna / swimming pool / water fountain

Q) how do you test the rcd (8 marks)

A) 50% --- 15ma---no trip
100%---30ma--- within 200ms
500%---150ma within 40ms

Q) when the new circit is connected, what will happen to the insulation resistance value, for the whole installation ?

A) the value will decreass

Q) why can you not do Zs-Ze to get the value for R1+R2

A) Ze may containe parralel paths

Q) why dose BS7671 state the mariner cannot be a T.N.C.S system

A) the dangers of water and electric / lower body resestiverty / contact of the body with earth potential.

Q) visual inspection in the shower block c.c.u, list 4 thing to look for (4 marks)

A) external influances
basic protection
correctly selected and erected
any visibal damage
Q) what in the above are you looking for (4 marks)

A) is there warter / dust ???
can some one touch live parts ???
in acordance with BS7671 ???
damage / ware and tear


Q) name 2 bits of infomation, that can only be obtaind via the supply authority.

A) ????? ????????? ????????? ???????? ????????????? ?????????????? ??????????

Q)name the 2 people who can decide the time for a periodic Inspection Report.

A) the designer / the tester

Q) work out the values for R1+R2 (3 marks)

A)0.96+127
-------- = 188
4
Q) name 3 things that may afect the next PIR date (3marks)

A) external influances
type of installation
maintenace shedual
Q) what is the maximum voltage drop for...
lighting ?
power ?
motor ?
A)3 %
3 %
3 % ( see page 358 in Bs7671)
............................Pm me for past pappers, and stuff ?...............................................

 

[BEDFORD ELECTIC]

Pm me for past pappers, and stuff ?
IF YOU CAN REMEMBER A 2391 MARCH 2011 MARINER QUESTION POST IT !

when conducting a insulation resistance test on the lamp post curcit, test between live conductors together and c.p.c.
its not practical to remove the contole gear
the photocell on top of the lamp-post must be coverd up to enable the onward wiring of the curcit to be included in the test.
( THE PHOTO CELL---- ACTS AS A LIGHT SWITCH----- all ways include the strapper wires ect ect )
500v dc


Q) discribe how you would conduct a insulation resistance test on a curcit that has SURGE PROTECTION ?

A) test at 500v dc as normal
(BS7671 443.2) surge protection is basicly a bolt of lightning hitting part of the installation.

Q) name 3 locations witch have zones

A) location containig a bath or shower / sauna / swimming pool / water fountain

Q) how do you test the rcd (8 marks)

A) 50% --- 15ma---no trip
100%---30ma--- within 200ms
500%---150ma within 40ms

Q) when the new circit is connected, what will happen to the insulation resistance value, for the whole installation ?

A) the value will decreass

Q) why can you not do Zs-Ze to get the value for R1+R2

A) Ze may containe parralel paths

Q) why dose BS7671 state the mariner cannot be a T.N.C.S system

A) the dangers of water and electric / lower body resestiverty / contact of the body with earth potential.

Q) visual inspection in the shower block c.c.u, list 4 thing to look for (4 marks)

A) external influances
basic protection
correctly selected and erected
any visibal damage
Q) what in the above are you looking for (4 marks)

A) is there warter / dust ???
can some one touch live parts ???
in acordance with BS7671 ???
damage / ware and tear


Q) name 2 bits of infomation, that can only be obtaind via the supply authority.

A) ????? ????????? ????????? ???????? ????????????? ?????????????? ??????????

Q)name the 2 people who can decide the time for a periodic Inspection Report.

A) the designer / the tester

Q) work out the values for R1+R2 (3 marks)

A)0.96+127
-------- = 188
4
Q) name 3 things that may afect the next PIR date (3marks)

A) external influances
type of installation
maintenace shedual
Q) what is the maximum voltage drop for...
lighting ?
power ?
motor ?
A)3 %
3 %
3 % ( see page 358 in Bs7671)
............................Pm me for past pappers, and stuff ?...............................................

 

[Paul.M]

Bedford well done for getting the questions but these are not word for word as per the exam, very close though. I can't believe no one took a quick picture or acidently pick up a copy just to put us out of our misery.

 

[BEDFORD ELECTIC]

it dose not matter about the wording for the questions ???
you know if they want you to list the FREEKING R.C.D times !
im just trying to jog peoples memorys, and work out if iv passed.

 

[BEDFORD ELECTIC]

in the discription of the mariner, it stated the earth electrode to be 1 meater in length ....and 100 ohms in resistance
see gidance note 3 (2.7.12)

 

[Jurasic Spark]

Think you mightn have some of these wrong. Post some more up and I'll check them.

Try the notes under tab 61 BS7671 p158 250vdc[/COLOR]
Q) name 3 locations witch have zones

A) location containig a bath or shower / sauna / swimming pool / water fountain

Q) how do you test the rcd (8 marks)

A) 50% --- 15ma---no trip
100%---30ma--- within 200ms
500%---150ma within 40ms

Q) when the new circit is connected, what will happen to the insulation resistance value, for the whole installation ?

A) the value will decreass

Q) why can you not do Zs-Ze to get the value for R1+R2

A) Ze may containe parralel paths. Thats why you need to disconnect the earthing conductor when measuring Ze. Zs is will contain parallel paths. You cannot get a resistance value by subtracting 2 impedance values.

Q) why dose BS7671 state the mariner cannot be a T.N.C.S system

A) the dangers of water and electric / lower body resestiverty / contact of the body with earth potential. Due to hazzards associated with loss of supply neutral and inpracticalities of maintaining a equipotential zone it is prohibited for certain locations under ESQCR

Q) visual inspection in the shower block c.c.u, list 4 thing to look for (4 marks)

A) external influances
basic protection
correctly selected and erected
any visibal damage
Q) what in the above are you looking for (4 marks)

A) is there warter / dust ???
can some one touch live parts ???
in acordance with BS7671 ???
damage / ware and tear


Q) name 2 bits of infomation, that can only be obtaind via the supply authority.

A) ????? ????????? ????????? ???????? ????????????? ?????????????? ?????????? Type and rating of their fuse. Nominal frequency.

Q)name the 2 people who can decide the time for a periodic Inspection Report.

A) the designer / the tester

Q) work out the values for R1+R2 (3 marks)

A)0.96+127
-------- = 188
4
Q) name 3 things that may afect the next PIR date (3marks)

A) external influances
type of installation
maintenace shedual
Q) what is the maximum voltage drop for...
lighting ? 3%
power ? 5%
motor ? 5%
A)3 %
3 %
3 % ( see page 358 in Bs7671)
[/FONT]............................Pm me for past pappers, and stuff ?...............................................

 

[chrissimm]

Looking at the answers in the above post as well aren't the trip times for a 30mA RCD at 100% within 300mA?

Cheers Chris

 

[Jurasic Spark]

Looking at the answers in the above post as well aren't the trip times for a 30mA RCD at 100% within 300mA?

Cheers Chris

That would depend on whether it was a BS number (200ms) or BSEN (300ms). I haven't seen the paper so don't know.