UK AM2 Fault Finding

[Georgemidnight]

Hi guys,

got my AM2 fault finding Resit on Monday and have a question.
How would I check for reverse polarity? If I test say from the board L N or E to say a switched spur if I put one probe on the board side L then the other probe on the spur N and I get a reading, surely that means the fault would be a short circuit not reverse polarity? As You can’t physically see any faults how can I check for reverse polarity?

 

[SparkyChick]

The same way as you would check for polarity at the incomers... 3 measurements... L-N - 230v, L-E - 230v, N-E - 0v = Correct. L-N - 230v, L-E - 0v, N-E - 230v = Reversed polarity.

Check it at the board on the outgoing MCB terminal, neutral/earth bars and then check it at the supply terminals of the FCU.

 

[Georgemidnight]

The same way as you would check for polarity at the incomers... 3 measurements... L-N - 230v, L-E - 230v, N-E - 0v = Correct. L-N - 230v, L-E - 0v, N-E - 230v = Reversed polarity.

Check it at the board on the outgoing MCB terminal, neutral/earth bars and then check it at the supply terminals of the FCU.

Sorry should of mentioned. Everything will be dead

 

[westward10]

Bit out of scope with college requirements these days but you do it by way of continuity. Link the line and cpc at the board and you should have continuity if correct polarity. You can also use your method of a wander lead. If something does not seem correct as in your suggestion then it isn't. To dismiss a short circuit you need to prove continuity of all conductors, end to end and between.

 

[SparkyChick]

Sorry should of mentioned. Everything will be dead

And I'm sorry, I should have remembered that

 

[ipf]

You say you're doing a RESIT tomorrow. It's basic stuff.
Are you saying you've already failed it once? If so, how long since and when did you do the course?

 

[Sparky5473]

I would carry out R1+R2 testing, this should identify reversed polarity

 

[Georgemidnight]

You say you're doing a RESIT tomorrow. It's basic stuff.
Are you saying you've already failed it once? If so, how long since and when did you do the course?

Yes I failed fault finding. Completed everything else. I’m currently in my 3rd year of my apprenticeship once I complete this Resit I’ll be qualified. I don’t have the opportunity to practice fault finding while house bashing
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I would carry out R1+R2 testing, this should identify reversed polarity

As I can reach from end to end surely I could just do the long lead method on continuity setting?

 

[ipf]

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As I can reach from end to end surely I could just do the long lead method on continuity setting?

You may be able to on an exam test rig but virtually no chance on a job....and that's what they're looking for (R1+R2 and polarity).
Dead testing, link cables at one end and test at the other for continuity and polarity, separate the lot for insulation resistance...and read up so you can do all tests in the correct order....it's an exam.

 

[Georgemidnight]

You may be able to on an exam test rig but virtually no chance on a job....and that's what they're looking for (R1+R2 and polarity).
Dead testing, link cables at one end and test at the other for continuity and polarity, separate the lot for insulation resistance...and read up so you can do all tests in the correct order....it's an exam.

They don’t mind how you find it as long as you find it and write down correctly. I’m on about fault finding by the way, I passed The testing part

 

[ipf]

They don’t mind how you find it as long as you find it and write down correctly. I’m on about fault finding by the way, I passed The testing part

When you’re saying it’s a short circuit, it’s the reverse polarity that’s causing the short. Still just link L and E at source and check at each point for continuity, proving polarity.