2391 Exam Questions !

[Zenn]

Zenn you have approached this forum in the correct manner. Well done sir.

When you post up these questions please have a go at answering them and let us correct you when your wrong. We are happy to help but we are not here to do your homework.

Zenn you've got our attention so don't waist it.

I am really happy to hear this man, I'm off from work next week for 10 days just for this exam lol. Ill try to answer them tomorrow when i got back from my work.

 

[sam80]

I'm doing the test the same day mate. Why did you say it your last time ??
Thanks Sam

 

[Zenn]

because they changed it to 2394 and 2395 and also I have failed twice before. do you want to go through the exam paper that I have posted and check our answers ? I can post section A as well on here.

 

[Zenn]

December 2011

Section (A)

1. The inspection of an electrical installation is being undertaken as part of the initial verification. state three conditions which must be verified, as far as is reasonably practical, during this inspection.

Answer :From Chapter 61 (Red Book)
611.2 The inspection shall be made to verify that the installed electrical equipment is:
i) in compliance with Section 511 (this may be ascertained by mark or by certification furnished by the installer or by the manufacturer), and
ii) correctly selected and erected in accordance with the regulations, and
iii) not visibly damaged or defective so as to impair safety.
_________________________________________________________________________________________________
2) State:

a) one statutory document
b) two non-statutory publications
to which the inspector may refer whilst carrying out an inspection and test of an electrical installation.

Answer:
a) Three main Statutory documents are:
The Health and safety at Work Act 1974 (HASWA)
The Electricity at Work Regulations 1989 (EAWR)
The Building Regulations Part P 2000

b) BS 7671:2008 Requirements for Electrical Installations
Guidance Note GS38 on Test Equipment
On-Site-Guide
Guidance Note 1-7
Code of Practice for in-Service testing of portable appliances.
_____________________________________________________________________________________________
3. State
a) two supply parameters which can only be obtained by enquiry to the Distribution Network Operator(DNO)
b) one supply parameter which may be obtained from either the DNO or measured by the inspector.

Answer:
a) any of this below:
The maximum Prospective short-circuit current at the supply terminals
The maximum earth loop impedance of the earth fault path outside the installation (Ze)
The type and rating of the distributors protective device or devices nearest to the supply terminals
The type of earthing system applicable to the connection
The number of phases of the supply
The frequency of the supply and the extent of the permitted variations
The voltage of the supply and the extent of the permitted variations.

b) I'm thinking of : The Earth fault loop impedance or The prospective short-circuit current.
________________________________________________________________________________________________
4. State the purpose of an initial verification process as identified in guidance note 3.

Answer :
To ensure equipment and accessories are to relevant BS or BSEN standards.
To prove compliance with BS 7671.
To ensure that the installation is not damaged so as to impair safety.
________________________________________________________________________________________________
5. State the three considerations which must be made when work is to be undertaken on or near live electrical equipment.

Answer: Correct me on this one
from EWR :
No person shall be engaged in any work activity on or so near a live conductor(other than one suitable covered with an insulating material so as to prevent danger) that danger may arise unless:
a) it is unreasonable in all circumstances for the system to be dead,
b) it is reasonable in all circumstances for the person to be at work on or near it whiles it is live; and
c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.

for live working to take place, each of the terms listed above must be complied with. In effect, a clear risk assessment must be made regarding the safety of any live working.
_______________________________________________________________________________________________________________
6. State for each of the following which instrument will have been used when the measured result is
a: 28 (ms)
b) 2.5 (kA)
c) 120 (ohm)Answer:
a) RCD tester
b) Prospective fault current tester
c)Earth electrode resistance tester
______________________________________________________________________________________________________________
7. List, in the correct sequence, the first three tests to be carried out on a newly installed ring final circuit.

Answer:
i) Continuity of ring final circuit conductors
ii) insulation resistance
iii) Polarity
______________________________________________________________________________________________________________
8. The resistance of a length of single conductor is 0.8 (ohm). Calculate the resistance of this conductor in ohm when the
a) length is doubled
b) length and csa are both halved
c) csa is doubled

Answer:
a) Double
b) same
c) half
_____________________________________________________________________________________________________________

 

[cossie400]

6
C- low resistance ohm meter?

7
I- continuity of cpc
ii- continuity of ring final circuit conductors
iii- insulation resistance

8
the question asks for the answer in ohms.....

 

[lauriehurman]

Beware!
I'm not an expert and I only have 2392 but I can spot a trap when I see one

The resistance figure you are given is for 20degs. You need to convert this to 70degs to take account of the 10amps.

Laurie




Easy marks this one! work out voltage drop Vd= IxLxOhms/1000 (remember resistance is in milli ohms)

Check this as a percentage of the supply voltage power 5% lights 3 % if under that no problem .

Read more: http://www.electriciansforums.net/i.../64856-2391-exam-questions.html#ixzz28C8O33Mp[/QUOTE]

 

[Zorro]

In reality you should read the OSG page 89-107, GN3 and BS7671 part 6 and appendix 6 for the model forms also the IET 2391 exam success book all the answers are within these books.

 

[loop3]

Zenn, I don't want to put you down mate, you're obviously an intelligent guy who wants change and opportunities like most of us. A word of advice, a good mate makes a good spark, a good spark makes a good tester/ designer, a... makes a good engineer. If you jump the gun, you'll have holes in your knowledge and experience. Make sure you cover it on site as well as reading the regs. There's no quick fix. Gifted you may be, but money can't buy experience. Good luck!

 

[Zorro]

Definition of competent in BS7671 A person who possesses sufficient technical knowledge, relevant practical skills and experience for the nature of the electrical work undertaken no mention of qualifications at all. I agree with loop3 totally start off as a mate/improver and get all of the above.

 

[Zenn]

Zenn, I don't want to put you down mate, you're obviously an intelligent guy who wants change and opportunities like most of us. A word of advice, a good mate makes a good spark, a good spark makes a good tester/ designer, a... makes a good engineer. If you jump the gun, you'll have holes in your knowledge and experience. Make sure you cover it on site as well as reading the regs. There's no quick fix. Gifted you may be, but money can't buy experience. Good luck!

so what is your suggestion mate? how can I find a job as an electrician?

 

[loop3]

Zenn, more on the matter, I was there once. Had all qualifications but no exp., mate, get out there! ASAP! Small companies like experience, big companies want to see qualifications. If you're out there with a big company, make sure you know you stuff, because its competitive! Especially at 2391 level. If small , pull your weight! I can't say more . Pm me for advice mate, I'd like to See you make something from your investment.

 

[loop3]

Theres lots of stuff the regs don't teach, it's not a best practice guide. It just says what should be done and what should not. Not a how to. Get on with the old olds and they'll show you. Hopefully the right way. I've helped many sparks pass the 2391 but, they worked with me. I don't think advice over messages will have the same impact. Start on doms, or coms, as a mate. Installing. Then do some maintenance to bring up your fault finding skills, the rest is your choice. Many directions after that- depends on you

 

[Zorro]

Zenn look for Electrician mates jobs, join agencies. Do you have you JIB ECS health & safety card? you will still need a good CV and references, even to get a job as an electricians mates.

 

[Zenn]

I've tried to pm you but it seem your pm inbox is full and you cant receive my pm.

 

[loop3]

Don't know if this will be blocked, [email protected]

 

[Zenn]

I do have cscs card and I registered with some agencies but because I didn't do any electrical job in the past and couldn't provide them any reference, they refused to introduce me to any contractors.

 

[Zenn]

all I need is someone who could give me a job and I will make sure to do my best and improve my skills while I work for them

 

[loop3]

Stop spending your money on advance courses. Get a mates job and start building your experience. Build your cv, make your contacts. Like I said, there no quick fix! Trust me. You'd av to be lucky. Experience. I don't want to throw basic install questions at you, because I know you won't know. Because they don't reach it in books. Believe me , get out there bro ! You're a mate . There's lots of peeps out there who will help! Meet them! Meet us! Were good people honest!!

 

[Zenn]

Thank you so much for your advice, I will revise hard to pass this and same time I apply for jobs, it is a hard time situation at the moment but it will never break me muwhahhaa.
Ill keep posting the exam questions and looking forward to see you guys correcting my answers, I have exactly one week to go!

 

[Zenn]

this is a paper that I took in July but I couldn't take a picture from all the questions.
it would be nice to have a look and figure it out what was the questions lol

2391 July 2012

Section (B)

A single story extension has been added to a hotel complex to create a fitness suite. A distribution circuit, rated at 63 (A), is installed between the existing intake position and a single-phase distribution board located in the reception of the fitness suite using steel wire armoured, 70 C thermoplastic cable with copper conductors. The fitness suite includes changing facilities with showers located behind the reception area. All exercise machines are connected to the fixed wiring of the new installation using switched fuse connection units. lighting is provided by modular high frequency fluorescent luminaires installed within a suspended ceiling. The new electrical installation is complete and is to be inspected/and tested.

The existing electrical installation forms part of a 400 V three-phase TN-S system with a Ze of 0.3(ohm) and a single-phase prospective fault current(pfc) of 2.3 (kA). There is sufficient capacity and spare way in the existing three-phase distribution board, which incorporates BS EN 60898 type B circuit breakers, to supply the new installation.
Testing will be carried out in an ambient tempreture of 20C.
Figure 1 below contains details of conductor resistance per metre at 20 C.
_________________________________________
CSA mm2 | Resistance m(ohm)/m at 20C
_________________________________________
1.0 ---------------- 18.1
1.5 ---------------- 12.1
2.5 ---------------- 7.41
4.0 ---------------- 4.61
6.0 ---------------- 3.08
_________________________________________

Q: A general purpose ring final circuit has been installed in the fitness suite for cleaning and display purposes.

a) State the maximum rating of the BS EN 61009 RCBO which could be installed to provide additional protection.

b) List the electrical tests to be carried out on the RCBO in a) above during initial verification stating the test current in (mA) and the maximum operating time for each test.
________________________________________________________________________________________________



Q. State why Zs - Ze cannot be used to accurately determine the value of ........