2394 questions

[philp]

I have been trying to pass the written 2394 for a while now. The course that I am on is sadly lacking. I passed the 2395, but am having terrible trouble with the 2394. I have loads of questions, but not sure where to go for the answers...I've given up on my course. The following questions are just some of the many questions that I have. I would appreciate any help.

1) General Question :- I would love to get hold of pass papers with answers so that I can study them. After spending thousands on my course I am trying to find a source for as little cost as possible. It annoys me that C&G do not publish past papers (preferably with answers). Any recommended books? I feel fairly happy on single phase, but have trouble with three phase. I only intend to do occasional domestic, so three phase and industrial does not interest me. But I need to study them for the exam.

2) Initial Verification is for a new installation. Does that mean that you do not need to do safe and secure isolation since the distributor is not connected yet? So for continuity, IR, Polarity you do not need to do Secure isolation. I believe that you do need to do an insulation resistance test between Line and earth after the distributor is connected (because the main earth is only present when distributor connected for TN). Not sure about TT? GN3 tells you that you must connect the cpc to the earthing arrangement in order to do the test, hence this must be done after the distributor is connected!!??!! Should these tests now be done after the distributor is connected in which case you would need to do safe ans secure isolation?

3) Order of tests. I have read the following:-

For example, it is of great importance that the continuity, and hence the effectiveness, of protective conductors is confirmed before the insulation resistance test is carried out. The high voltage used for insulation testing could appear on all extraneous metalwork associated with the installation in the event of an open-circuit protective conductor if insulation resistance is very low.

I am having difficulty understanding the full meaning of this statement. Is it a no-no to connect the +500 volts red lead to the cpc...should the red lead always be connected to the live conductors? Basically it would mean that all extraneous metalwork would have the high voltage straight away without the low insulation resistance. Also, even though 500 volts have been put across the tester terminals...only if you touch a live conductor and the extraneous part will current flow...the fact that an extraneous part has 500 volts on it does not mean that current will flow through you if you touch it? Its got to go back through the tester!!! What about the exposed parts? Why is it now a requirement that the cpc is earthed/grounded through the distributor?
My answer to the insulation resistance after continuity would be that your not testing insulation resistance on the whole circuit...I'm a little confused about the statement above....Please put me out of my misery

Sorry for all the questions....

Thanks

 

[andyelectric]

I think you sound dangerous mate, and in so many ways I fear you will not be getting any help here but merely a ribbing. Suggest you find out exactly what a new installation is, and revisit safe isolation is all I will say.

 

[Pete999]

I have been trying to pass the written 2394 for a while now. The course that I am on is sadly lacking. I passed the 2395, but am having terrible trouble with the 2394. I have loads of questions, but not sure where to go for the answers...I've given up on my course. The following questions are just some of the many questions that I have. I would appreciate any help.

1) General Question :- I would love to get hold of pass papers with answers so that I can study them. After spending thousands on my course I am trying to find a source for as little cost as possible. It annoys me that C&G do not publish past papers (preferably with answers). Any recommended books? I feel fairly happy on single phase, but have trouble with three phase. I only intend to do occasional domestic, so three phase and industrial does not interest me. But I need to study them for the exam.

2) Initial Verification is for a new installation. Does that mean that you do not need to do safe and secure isolation since the distributor is not connected yet? So for continuity, IR, Polarity you do not need to do Secure isolation. I believe that you do need to do an insulation resistance test between Line and earth after the distributor is connected (because the main earth is only present when distributor connected for TN). Not sure about TT? GN3 tells you that you must connect the cpc to the earthing arrangement in order to do the test, hence this must be done after the distributor is connected!!??!! Should these tests now be done after the distributor is connected in which case you would need to do safe ans secure isolation?

3) Order of tests. I have read the following:-



I am having difficulty understanding the full meaning of this statement. Is it a no-no to connect the +500 volts red lead to the cpc...should the red lead always be connected to the live conductors? Basically it would mean that all extraneous metalwork would have the high voltage straight away without the low insulation resistance. Also, even though 500 volts have been put across the tester terminals...only if you touch a live conductor and the extraneous part will current flow...the fact that an extraneous part has 500 volts on it does not mean that current will flow through you if you touch it? Its got to go back through the tester!!! What about the exposed parts? Why is it now a requirement that the cpc is earthed/grounded through the distributor?
My answer to the insulation resistance after continuity would be that your not testing insulation resistance on the whole circuit...I'm a little confused about the statement above....Please put me out of my misery

Sorry for all the questions....

Thanks

Are you a trainee Philp? might be best if you are to get access to the trainee forum, otherwise you will get no end of grief coming up with questions like yours, if on the other hand you are a chancer you will probably all you deserve, sorry mate just saying like it is, or will be.

 

[trev]

A new installation is not necessarily a new build, it could be a new circuit or a rewire and in both cases the service head will be there and the installation will be live.
Now, what was that about safe isolation again?
If you do not perform the safe isolation procedure you are putting yourself at risk of grabbing a handful of juice which isn't going to be a fun day out.
The exams do not and cannot differentiate between those who work on all types of installation and those who only work on domestic or single phase (still cannot get used to calling them lines) supplies so you'll have to get interested in 3 phase if you want to pass.
Now have a good think about the order of the tests on an IV and why they are carried out in the order they are. The continuity of protective conductors is testing what and why?
These exams are not easy mate, they exist to sort the wheat from the chaff.

 

[brin the snail]

And the point of learning, training and exams are?
Sounds like another who wants to shake hands with the Grim Reaper?

 

[brin the snail]

Seriously Philp. The other questions I would ask you are:
Where are you taking this course if you think its sadly lacking?
Is it a recognised training establishment, are the instructors qualified?
What qualifications do you already hold?
Did you pass the 2395 with ease or?
If it’s costing you an arm and a leg and you feel you not getting value for money have you said anything to the instructors?
Please, whatever you do don’t try and just bluff your way through this. You could end up seriously hurting yourself or god forbid someone else.

 

[andyelectric]

Echoing Trev, I also suggest you discard your disinterest in 3 phase. Large houses, flats, garage workshops all examples of where you might find 3 phase domestically.

 

[trev]

Brin if it's anything like 2391 the practicals are closely supervised and if the candidate does anything dangerous the exam is stopped immediately and it's an automatic fail. As you say though, failure to carry out safe isolation on the job can mean an appointment you'll never know about with a funeral director.
@Philp I've worked in a good few houses over the years that have had a 3 phase supply so you need to know this stuff.

 

[Plonker 3]

Op I suggest before you go any futher you go to college and do the relevant C&G course over 2 or 3 years to get conversant with 3 phase systems before progressing any futher with any type of electrical work or courses.