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

L

lynj

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

anyone else take it?
 
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brucelee said:
yeah would be good if someone had forgot to hand a copy in then we could all see the questions as they were written as with C&G the exam is in the wording
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Yes, I've asked 2 or 3 times in this thread-the problem is that a seemingly minor detail missing from the question can result in an entirely different answer!

Not that you need to worry Bruce, sitting with the certificate that took 6 months to arrive!
 
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Unfortunately I was sitting at the back of the room too close to the examiner to take a photo and no chance of accidentally picking a copy up. Wish I did now after the confusion on this thread about what wording is correct for the questions.

Oh well I've got the practical exam in the morning. At least wires and cables don't misinterpretate the truth.
 
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Good luck, and remember don't stop looking when you've found the required number of faults. Half of them will probably be accidental.
 
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safely isolate, lock off, label and retain key in pocket not tool box or fail as a result and check for dead with approved GS38 voltage indicator then check tester on proving unit or known supply to prove working at time of test then re - check for dead
 
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paul.m said:
Unfortunately I was sitting at the back of the room too close to the examiner to take a photo and no chance of accidentally picking a copy up. Wish I did now after the confusion on this thread about what wording is correct for the questions.

Oh well I've got the practical exam in the morning. At least wires and cables don't misinterpretate the truth.
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GOOD LUCK paul
with the practical dont rush to much just think about what you doing its not as bad as you think but the waiting to do it is the worst work methodically
 
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Cheers guys, the only thing I'm concerned about is testing the 3 phase commando plug that is on one of the rigs. I know its on there because I've seen it and I have a "photographic" memory ;);).

Testing is not that difficult but when you've got an examiner sitting on your shoulder makes you think if you've missed a step. As you've said, take a methodical approach and everything will be fine.

Practical tomorrow, cscs exam Saturday and starting a new job Monday, happy days. One week trial/depending on work load but its better than sat at home waiting for the phone to ring, and its a good firm.
 
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the three phase command is easy mate i had never tested one before
just link L1 and cpc at DB then find the correct terminals at the socket by pushing probes in the end dont need gs 38 4mm tips for dead tests of socket or the rear connections of the socket easy mate then record the highest as thats the worst case scenario
eg
L1 - cpc = 0.2ohm
L2 - cpc = 0.3
L3 - cpc = 0.2

L2 - cpc is the R1 + R2 you need to record on your schedule of test results
on the relevent line
 
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for the 3 phase commando it covers 3 lines of the schedule complete middle line and use brackets for all three lines
when you test the zs for the distribution circuit from the 3 phase db this is also your Ze or ZDB for the single phase board and calculate Zs all circuits except sockets mate even calc the zs for 3 phase commando and then right calc ZS in the remarks column at side of the relevent circuit

on radial circuit with fused spur check R1+RN also to prove continuity
on two way switches operate individually whilst conducting further tests
for continuity proves polarity when measuring R1 + R2 and for IR it ensures all circuit tested
do
all dead tests dont forget to do the main protective bonding and disconnect 1 end to remove parallel paths start on 3 phase dead tests put things back as you go then single ccu then polarity live then Ze pfc on three phase put covers on switch on make sure everything reconnected first do Zs and then rcd tests and PRESS the test button then rest of functional tests finish cert etc
before you start complete as much of cert info as you can like client details etc records of previous certs etc last test date and so on so so you have as much of the main pir done before you start the actual testing
DONT FORGET SAFE ISOLATION AND RETAIN THE KEY IN POCKET
 
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PAUL dont worry mate the examiner keeps his distance just watches from afar apart from at key moments especially the safe isolation then he basically leaves you to it and if you ask him he will tell you when you have 30 mins left out the 90mins ask his permission to isolate and lock off check meter ok leads and functioning
 
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Ok I've managed to get a quick look at the paper. And question 26 asks about the rating of the RCD needed to provide fault protection on the newly installed lighting circuit.

Tab 41.5 on p50 of BS7671 gives max Zs values for ratings of RCDs used for fault protection on TT installations. And where a 500mA RCD is used max Zs is stated as 100 ohms.

The Scenario states that the earth electrode resistance is 100 ohms so therefore the Zs for the lighting circuit is going to be 100 ohms plus the R1 + R2. So it would be a a 300mA RCD not 500ma as most replies on this thread have stated.

But then again you might get it marked correct as I'm doubtful that C & G have thought it through properly.
 
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IQ Electrical said:
Yes, 500mA is my opinion too, where is the requirement to size a front end RCD on a TT system from anything else other than Ra?
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Tab 41.5 on p50 of BS7671 gives max Zs values for ratings of RCDs used for fault protection on TT installations. The Zs by definition must surely include R1 + R2 ?
 
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RA doesnt include R1 i dont think mate its just R2 thats included
and if C&G just gave 100ohms as the Ra then i agree with 500mA protection
its just easier to measure R1 + R2 then add this to Ze but really the R2 should be measured with method 2 R2 with use of long wander lead and then added to the Ze
but Ra as far as i am aware doesnt include R1 just got me looking at the regs now lol
 
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Read note 1 under the table. it will tell you how to arrive at the Zs. Ra x IdN same or below 50v.

So 50/100 = 0.5 or 500mA.

Ra is the sum of the earth electrode and the earth conductor (Reg 411.5.3). as the earth conductor will be negligible possiblly 0.05ohms then your only concern in the question is the 100ohm of the electrode
 
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yes mate it does say where ra not known it may be replaced by Zs note 2
and used where the device is a overcurrent protective device the following shall be satisfied
Zs X Ia less than or equal to Uo
for TT system where RCd is used for earth fault protection
Ra X I delta n is less than or equal to 50v

be good to see this paper after all comments about did no one find a copy in there bag lol
 
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brucelee said:
Ra is the sum of resistances of the earth electrode and the protective conductor connecting it to the exposed conductive part
Click to expand...

Yes this is true. But believe me, I have checked the wording and it does NOT say RA is 100 ohms. What it does say is "TT system with earth electrode resistance of 100 ohms."

Q26 then asks you to determine the the max permissible operating current for the BSEN 61008-1 RCD protecting the lighting circuit. This has to include the R1 + R2 of the lighting circuit??? Think about it... if you get an earth fault at the extremity of the circuit then the fault current is determined by the value in ohms at that point.

Hope I'm not confusing things just shows the confussion, deliberately or not, caused by the wording in C & G exams.
 
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Thanks but my iterpretation is it is giving you the RA in the question.

"""What it does say is "TT system with earth electrode resistance of 100 ohms."

I must say I bet alot of people are now more up to date with TT systems and RCD protection.
 
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it is not my question but that of city and guilds in march 10th 2391 exam, but i now what you mean because i thought the same thing when i read the question in the paper. I cant quite remember the wording of the qustion exactly though.
 
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Not knowing the exact wording of the question all the statatory documents you are use to apply but I am guessing that the answer may be that the in the UK ESQCR 2002 prohibit the use of TN-C-S system for the supply to boat or similar construction

Open to other opinions
 
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Nice one Stu, I was looking for this thread but couldn't find it earlier. The results are out, how did you do?
 
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I spoke to Scottish Power and because of the wording of the questions City and Guilds have remarked a pile of test papers. We have been told to expect exam results about 18th June. I was forwarded a letter from C&G to Scottish Power explaining this.

I am only presuming that if you flat out failed you have been told, if you aced it you have been told and if you are borderline because of the scenario questions you are being marked again - only my opinion of course. C&G gave no explanation in the letter as to why the papers were being marked again apart from it was to give a fair mark.

Here is the text from the letter -

"Dear Examination Officer,
Subject: Examination 2391-301 held on 10 March 2011

As you may be aware, results for the above examination were due to be published on 3 May 2011. In order to ensure the validity of all marks, City and Guilds is implementing an additional quality check on the marking for this examination, which includes a number of scripts completed at your centre, This will consequently delay receipt of results. The latest date results will now be available on Walled Garden is Friday 18 June2011.

I hope you understand the importance of checking that all candidates receive a fair mark. We apologise for any inconvenience this may cause you or your candidates affected by this. For future examinations, we are taking measures to ensure such quality assessments are carried out within the publicised result release date.

We will waive the late entry fee for any candidate whose result is not released in time to enter for a July or August 2011 re-sit. Should you need to make such an entry for July or August please contact.

Yours Sincerely,

Joel Bild
Lead Assessment Manager
Learning &Assessment Developement
City & Guilds "

Cheers Chris
 
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Cannot believe that I have passed !!!
They must have been very lenient with a couple of the second part questions as I thought that I had made a right grumbling of it. Congrats to all others who passed and best of luck for the next one to those who did not - it must be more straight forward after all the problems that this one caused.
 
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Well done Newby, feels good doesn't it. I thought the same as you, thought I'd fluffed the scenario questions by giving some real pants answers, mine must have been a real scrape but a pass is a pass Woo hoo!! I wonder what the national pass rate was on this one.
 
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well done guys they like keeping you guessing the chief examinors report of C&G website will tell ya pass rate but dont know if its out yet plus it lets you know the areas candidates struggled with

Anyway CONGRATULATIONS TO ALL
 
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Previous papers are available but if I was you I would study GN3 and get hold of a copy of

City andGuilds Exam Success: Inspection and Testing (IEE Wiring Regulations)

This will show you would C&G are looking for
 
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I have a copy of Exam Success and have been reading the GN3, but just want some papers to go over the scenarios in section B
 
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