2391 exam question

[WayneL]

Widdler

Where's your 'thanks' gone???

 

[Sparky Ninja]

Widdler

Where's your 'thanks' gone???

I'm using my iPad and have fat fingers. But if it upsets you I will put it back.

 

[breakerman]

Wow..........Where did that come from???

just got goin on 2391...

 

[WayneL]

Breakerman - do you mean you've been on your first lesson/lecture?

 

[WayneL]

Got yah

Posted the same time as you, then.

 

[breakerman]

Breakerman - do you mean you've been on your first lesson/lecture?

yep, just earlier

 

[WayneL]

on 2391; got to look at IP codes, also 4 practical assesments (1) installation inspection-12 faults to find (2) insulation resistance 6 faults (3) earth fault loop-impedance test (4) three phase+sigle phase testing TPN dist board-feeds sib mains consumer unit+ DOS...phew' lots of stuff, any input on this would be fab... cheers

Number (4) is the 'biggy', the others are fairly straight forward.

Whatever you do, don't leave it all to the 3 hours in the lesson. Do loads of reading up at home and try anticipate what you will be covering in your next lesson - so that you can have any questions ready.
Obviously, if you can, try get some practical practise - because you don't always get a lot of practical time on these courses.

 

[trebor]

Read the question, it states individual circuits can be isolated, this would include rfc tests. This is a C&G question not real life, they are after the 3 tests stated in GN3 to be carried out with the installation isolated, it says you can for an hour , you dont have to take an hour

 

[breakerman]

Number (4) is the 'biggy', the others are fairly straight forward.

Whatever you do, don't leave it all to the 3 hours in the lesson. Do loads of reading up at home and try anticipate what you will be covering in your next lesson - so that you can have any questions ready.
Obviously, if you can, try get some practical practise - because you don't always get a lot of practical time on these courses.

oh gr8, thanks

 

[WayneL]

Read the question, it states individual circuits can be isolated, this would include rfc tests. This is a C&G question not real life, they are after the 3 tests stated in GN3 to be carried out with the installation isolated, it says you can for an hour , you dont have to take an hour

What page?

 

[trebor]

Page 74 3.10.3
Top of page 50 referring to 610.1

 

[Baal]

I keep going back to the 1-hour proviso-this is an industrial unit, not a simple domestic installation!

There could be 50-100 circuits, maybe 15 ring finals, 60 minutes!!!

The City & Guilds answer is:

Continuity of main protective bonding conductors

External earth fault loop impedance

Prospective fault current

 

[Sparky Ninja]

I keep going back to the 1-hour proviso-this is an industrial unit, not a simple domestic installation!

There could be 50-100 circuits, maybe 15 ring finals, 60 minutes!!!

The City & Guilds answer is:

Continuity of main protective bonding conductors

External earth fault loop impedance

Prospective fault current

A bit like that guy said on post #3.

 

[Baal]

Yes, that guy knows his stuff!

 

[WayneL]

I keep going back to the 1-hour proviso-this is an industrial unit, not a simple domestic installation!

There could be 50-100 circuits, maybe 15 ring finals, 60 minutes!!!

The City & Guilds answer is:

Continuity of main protective bonding conductors

External earth fault loop impedance

Prospective fault current

Sorry, but I can't accept that one.

612.11 ...........at the origin and other relevant points of the installation.

If you have your main DB and 6 sub-DBs, how are you measuring PFC at the 6 sub-DBs (relevant points) of the installation with the supply off??

A bit like that guy said in post #55 - "Can't understand why people think Prospective Fault Current needs to be tested with the installation isolated"......

....and I agree.

As for 'Continuity of main protective bonding conductors' - they don't necessarily have to be disconnected.

As GN3 states on PG 74 - The use of an 'Earth Fault Loop Impedance Tester' is often the most convenient way of continuity testing.

So, I'll give you Ze - only kidding, if it's isolated you might as well do Protective Bonding Conductors......but I can't accept PFC.

The only thing I can find for definite in GN3 is two statements saying "Switch off the supply before disconnecting the earth" - so Ze and Earth electrode resistance.....and PBC.
(I don't know the scenario earthing system)


As an additional thought, I'd go for:

External Earth Fault Loop Impedance

Main Protective Bonding Conductors

Supplementary Bonding Conductors