2391

[thomo27]

Good Evening ,

I have my 2391 Practical exam on Monday and a few concerns that Im hoping you can help me with

Test 1 - Visual inspection find x amount of faults.. im sure I will be OK with this one
Test 2 - 2 x Insulation Resistance tests... we are to do a complete test so am I right in saying it is main switch off but all MCBS switched on ??

The examiner then flicks a switch and puts a fault on the circuit - I guess the logical way to fault find is to knock off an MCB at a time and retest until by process of elimination you find the faulty circuit (however Im told it can be a N-E fault too) is this how you would approach this test ?

Test 3- Earth Fault loop Impedance Im Ok with this part of the test



Then its onto the full test which I aim to tackle in the following steps
1.Safe Isolation
2.Continuity of bonding and protective conductors
3.Polarity
4.Continuity of Ring Final Circuit Conductors
5.IR ( am I right in saying this will be main switch off and all MCB's off as im sure we have to test each circuit individually )

Im confident up to this point but from here I could do with some clarification so please correct me if im wrong but I think this is the order they want

6.Check supply polarity

If all OK is it time to power up at this stage before your phase rotation ?

If so is it then
7.phase rotation
8.ZE
9.PEFC&PSCC
10.ZS
11.RCD
12.Functional Testing

Im confident enough in the tests but would like some clarification on the order so if you have recently taken the 2391 or even if you havent can you confirm what order you would look to do the tests

Cheers

Stephen

 

[ban-all-sheds]

Can't help you much re 2391, never having done it, but you do come across as either not adequately prepared or for some reason lacking in confidence.

Hopefully a few of the electricians here will be able to help, but you might have left it a bit late - posting at 20:50 on a Friday when your practical is on Monday.

One observation I'd make is that your testing sequence looks wrong - CRIPPLER?

 

[dingbat]

I guess the logical way to fault find is to knock off an MCB at a time and retest until by process of elimination you find the faulty circuit...

This is the illogical way to do it. You either batch test or test individually.

Then its onto the full test which I aim to tackle in the following steps...

It's a Periodic Inspection. The order of tests is expected to be the same as stated in BS 7671, Chapter 61, but you should not be failed for any sequence that's safe and effective.

 

[thomo27]

Can't help you much re 2391, never having done it, but you do come across as either not adequately prepared or for some reason lacking in confidence.

Hopefully a few of the electricians here will be able to help, but you might have left it a bit late - posting at 20:50 on a Friday when your practical is on Monday.

One observation I'd make is that your testing sequence looks wrong - CRIPPLER?

Maybe a bit of both BAS

Yeah Ive heard of CRIPPLER , the tutor advises we test Polarity (dead) after Continuity so its more CPRIPLER , his reason for this is due to how fast the time goes in the test

 

[thomo27]

I guess the logical way to fault find is to knock off an MCB at a time and retest until by process of elimination you find the faulty circuit...

This is the illogical way to do it. You either batch test or test individually.

I have 20 minutes for the 2 IR tests where a fault is added on each so maybe they advise to flick the MCBS on and off to try and find the fault quicker , however if its a N-E Fault then testing individually would be better

Then its onto the full test which I aim to tackle in the following steps...

It's a Periodic Inspection. The order of tests is expected to be the same as stated in BS 7671, Chapter 61, but you should not be failed for any sequence that's safe and effective.

 

[dingbat]

I guess the logical way to fault find is to knock off an MCB at a time and retest until by process of elimination you find the faulty circuit...

This is the illogical way to do it. You either batch-test or test individually.

I have 20 minutes for the 2 IR tests where a fault is added on each so maybe they advise to flick the MCBS on and off to try and find the fault quicker...

No. You either batch-test or test individually. (All off, then test one at a time)

If you start trying to see which individual circuit breaker removes the fault you will get confused in a situation where multiple faults are present.

however if its a N-E Fault then testing individually would be better

It's exactly the same... except you will need a screwdriver.