Prospective Fault Current

[babyshanks]

Hi guys. I just got the results back for my AM2 and I passed everything except the PFC. I now need to go back and do the whole testing proceedure again which I am gutted about.

When I tested the PFC, I don't think I had three leads from my tester, I seem to remember only seeing two leads and using them on the earth and P1, P2 and P3. Is the neutral lead mandatory for a PFC test?

And if I remember correctly, I got 771kA, in hindsight, this seems too large to be correct, am I right? I don't know what was going through my head at the time of taking the test, I guess I didn't think a mistake on the PFC would be enough to fail the whole exam.

Any help is greatly appreciated.

 

[ezzzekiel]

depends on the tester being used wether 2 leads or 3 but generally
take pscc between l/n
take pefc between l/e
record the highest as the pfc

 

[WayneL]

Hi mate,

Between all three phases and earth (3 tests) - PEFC - note highest reading

Between all three phases and neutral (3 tests) - PSCC - note highest reading

Between phases (if they, and your meter, allow you to) (3 tests) - note highest reading.

On a three phase installation the PFC will be the highest of the phase to phase readings.

If you can't measure phase to phase, take the highest reading out of your PEFC & PSCC and double it - this is then your PFC.

My Megger is a two lead tester - depends what you're using.

 

[brucelee]

Hi guys. I just got the results back for my AM2 and I passed everything except the PFC. I now need to go back and do the whole testing proceedure again which I am gutted about.

When I tested the PFC, I don't think I had three leads from my tester, I seem to remember only seeing two leads and using them on the earth and P1, P2 and P3. Is the neutral lead mandatory for a PFC test?

And if I remember correctly, I got 771kA, in hindsight, this seems too large to be correct, am I right? I don't know what was going through my head at the time of taking the test, I guess I didn't think a mistake on the PFC would be enough to fail the whole exam.

Any help is greatly appreciated.

hi mate
did you only measure pefc i.e between L1-E, L2-E ,L3-E , what about pscc L1-N, L2-N,L3-N
A three lead tester i.e a fluke multifunction needs the neutral lead to power the meter
where as a megger 1552 only uses two leads
and the highest L-N (pscc) value is multiplied by 2 and this is then recorded as the £ phase PFC as the highest will always be between the lines but you cant measure L1-L2 with certain meters so this is why you multiply by 2 as this figure is a rule of thumb figure and errs on the side of safety

 

[wacko]

Hey babyshanks,

PSCC - as a picture paints a 1000 words,
Practical Guide to Inspection, Testing and Certification of Electrical Installations: Conforms to IEE Wiring Regulations / BS 7671 / Part P of Building Regulations: Amazon.co.uk: Christopher James Kitcher: Books

PEFC - same as Ze test, L and N and E, but with main earth connected

Regards

 

[Des 56]

And if I remember correctly, I got 771kA, in hindsight, this seems too large to be correct, am I right?
Any help is greatly appreciated.

Thats a monster of a fault current
Gold conductors perhaps

The test as advised, and make sure what you are stating "771KA" that you are not meaning 771 amps and that if it was a single phase reading that you doubled it also as advised previously

 

[WayneL]

Hey babyshanks,

PSCC - as a picture paints a 1000 words,
Practical Guide to Inspection, Testing and Certification of Electrical Installations: Conforms to IEE Wiring Regulations / BS 7671 / Part P of Building Regulations: Amazon.co.uk: Christopher James Kitcher: Books

PEFC - same as Ze test, L and N and E, but with main earth connected

Regards

Except that it wouldn't look like that because he's working on a three phase board

 

[wacko]

Hi Wayne,

I didn't read the OP properly. Usual Sunday hangover!

 

[babyshanks]

Turns out it wasn't the PFC I failed on, but it was not doing the functional on the RCD, d'oh! Thanks anyway!

 

[fog]

Hi
As i understand it
all three phases and earth (3 tests) - PEFC - note highest reading --------do not double these readings
all three phases and neutral (3 tests) - PSCC - note highest reading ------only double these readings
On the AM2 the only reason with a meggar 1552 to use the third test lead was their supply to test rig was via an RCD!
the highest reading is what is recorded as PFC.