2391 question, SPD"s

[sparkysam]

Hi there all, got my 2391 theory in a couple of weeks and ran through some questions with the tutor, but 2 tutors giving different answers, what is the definitive answer , A test of IR is to be carried out on a 230v circuit that contains a surge protective device which cannot be disconnected , state the ...

A) test voltage to be applied

B)conductors between which the test is to be conducted between

I answered 250v dc and tested between live conductors to earth , , it's not definitive in the GN3 either

The tutor says test at 250v between all conductors as it doesn't state in the GN3 if you reduce the voltage to also test between live conductors to earth , then the other tutor said the same as me, WTF!!

 

[Sidewinder]

You can't use over 250V.

If the SPD is at the origin, is the N still connected to the supply?

i.e. single pole isolated?

If so then on a TN system you will get almost a dead short N-E

It won't say much in GN3 as the "new green" GN3 is not yet out.

 

[sparkysam]

It's a question on the current GN3 out atm, the question doesn't state whether it's at the origin, that's city and guilds at its best

 

[Sidewinder]

I have not taught 2391 since the 1st Jan, so I have not seen any of the new sample Q's.

IIRC SPD are not covered in the "red gn3".

Do they mean disconnected or isolated?...

Don't you just LOVE C&G Q's!

MI's could also have something to say.

Thing is as it's a written exam you have to opportunity to show the examiner that you have the underpinning knowledge to fundamentally assess the problem and derive a solution from this.

 

[m4tty]

I'd go with 250v between live conductors (l&n) connected together to earth

 

[sparkysam]

It has a few silly questions in all there papers, it's more of a task just to get at what they want from the answer , really badly worded questions , Thought the same as you m4tty

 

[m4tty]

I always stick 250v down it first to see if the lines clear then do 500v. Prob why my Megger eats do many batteries lol

 

[SPECIAL LOCATION]

Hi there all, got my 2391 theory in a couple of weeks and ran through some questions with the tutor, but 2 tutors giving different answers, what is the definitive answer , A test of IR is to be carried out on a 230v circuit that contains a surge protective device which cannot be disconnected , state the ...A) test voltage to be applied

B)conductors between which the test is to be conducted between

I answered 250v dc and tested between live conductors to earth , , it's not definitive in the GN3 either

The tutor says test at 250v between all conductors as it doesn't state in the GN3 if you reduce the voltage to also test between live conductors to earth , then the other tutor said the same as me, WTF!!

1/ Look again at the question.....

2/ Look again at guidance note 3 pages 37 thro 40 of guidance which clearly describes test methods and table 2.2. on page 38 which describes the voltages...

3/ Now look at the little blue number in the margin of GN3 it says Table 61...

4/ Go and check table 61 on page 191 of BS7671...

5/ The paragraph under table 61 starts with the wording..

"Where surge protective devices (SPDs) ..... blah... blah... blah.."

Read the rest of that paragraph...

Learn it..

Write it down as your answer...

Its all there in the books recommended for use in the 2191 IMHO!



They are trying to get you to learn to navigate all of the relevant publications..

there are enough clues in the question to find the clearly defined answers..

i.e

test voltage.. between where... expected min valule..