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Hello all,

I’m now overthinking the - Prospective fault current test for the 2391 practical, the exam boards will be a 3 phase and a single phase board.

Do I test the three phase board and double the highest and use that for both DB’s or do I do one for 3 phase db1 and sep one for single phase db2
 
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H

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Arms
The three phase board will be the origin, for the office just remember to record the Zdb and ipf information, top left on the schedule of test results
 

Strima

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Arms
Esteemed
Test as close to the source as possible with parallel paths in place.

Test all three phases to earth then all three to neutral.

If your test meter is capable then test across all phases, L1 to L2, L2 to L3 then L2 to L3.

If you can’t test phase to phase then double the highest single phase measurement.

Do you know the difference between PSSC & PEFC?
 
  • Thread Starter Thread Starter
  • #8
Test as close to the source as possible with parallel paths in place.

Test all three phases to earth then all three to neutral.

If your test meter is capable then test across all phases, L1 to L2, L2 to L3 then L2 to L3.

If you can’t test phase to phase then double the highest single phase measurement.

Do you know the difference between PSSC & PEFC?
Yes I’m ok with that, Thank you
 

Richard Burns

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Mentor
Arms
Esteemed
Prospective fault current at origin is the highest current, further into the installation the current will drop due to circuit resistances.
If the protective devices in the next DB are able to withstand the fault current at origin there is no need to measure again at the next DB because you already know they are OK.
 

H

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Arms
Of course...

1) High reading on Main protective bonding conductor.

2) Low insulation resistance on the sub board / office board between neutral and earth.

3) No cpc continuity on the switch wire on one of the lights on a lighting circuit.

Also had a couple of high Zs readings due to poor connections and contact resistances.
 
D

Deleted member 26818

Looking at that test rig, there are 10 possible faults.
 
  • Thread Starter Thread Starter
  • #16
Of course...

1) High reading on Main protective bonding conductor.

2) Low insulation resistance on the sub board / office board between neutral and earth.

3) No cpc continuity on the switch wire on one of the lights on a lighting circuit.

Also had a couple of high Zs readings due to poor connections and contact resistances.

Thank you,

Wish me luck my test is tomorrow
 

Baddegg

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Arms
Supporter
Esteemed
Good luck mate,take ya time think it through it’s not as hard as you are thinking, you’ll look back in a years time with test experience under ya belt and wonder what you were stressing about....
 
T

The Ghost

We had a potential of 35 fault injections and the cards were numbered and each candidate was given several random fault numbers which they injected. There is no way to know what faults you will be given. Except that there are only so many faults possible like short, no continuity, high resistance, low resistance and wrong polarity and maybe a few others all of which will be within your meters ability to spot so long as your brain is ok. Thing is to keep calm and work methodically with all fault finding.
 
  • Thread Starter Thread Starter
  • #28
What faults did you have?
A massively high continuity cpc reading on a final ring circuit,
Missing L1 connection at the socket of my 3phase motor circuit (think that’s done to make sure you test all 3 phases from the switch to the socket,
Bonding conductors not labelled.
 
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