AM2 a few revision questions

[Elliott96]

Im taking my AM2 on Monday and have a few questions just to get my testing on point. Firstly when testing continuity of cpc would a the assessor expect each cpc to be connected to the line conductor in a connector block for example (separately from the earth bar to eliminate parallel paths)? Or would a link from the earth bar to the load side of the circuit breaker for each circuit be acceptable?

Also when testing polarity do you think that the assessor would be happy for this to take place while testing Continuity of Cpc or would he/she expect it to be done after insulation resistance (as the sequence of tests is written)?

Also when testing PSCC on a 3phase install GN3 says if the meter being used can test between for example two phases (L1+L2) then the highest reading should be divided by 0.87 am i reading this correctly? As i have always only been told to double the highest reading when using a meter than cannot test between two phases.

With safe isolation (dont want to fall at the first hurdle) should the main distribution board be safely isolated and locked off before removing the cover? Because either way it will have to be reenergised (with the lid off) when testing PFC anyway or am i wrong?

Thanks

 

[MJPD29]

The first test you described there is r1+r2 not continuity of cpc

 

[SparkyChick]

The preferred method of testing continuity is R1+R2 (Method 1 in guidance note 3 - the reason will become apparent in a mo). Since you are testing a new installation, you should know whether there are parallel paths present. I took the CPC out the block and linked it to the line using an assessment centre provided Wago.

Polarity... Guidance Note 3 (familiarise yourself with it so if asked you can point the assessor to it) states you can prove polarity through a combination of visual inspection and R1+R2 testing.

What you're interested in is the Prospective Fault Current. It is acceptable to measure this from Line-Earth for each phase, take the highest value and double it. In reality you would, if your meter is capable, test between phases but in the AM2 it's acceptable to measure Line-Earth and double up the highest.

Just as you'll probably be advised to calculate Zs. In reality I like the security of measuring it but for the AM2 where time is short, you calculate it using the highest Ze value, but remember to add a remark to each line of the cert saying "Zs by calculation".

You will do two sections of safe isolation. I found it wasn't possible to remove the board cover with the lockout device on, so for the first stage (which is effectively proving your bay is safe for you to work on - this is done with the risk assessment section) I turned the board off (don't forget to ask if this is OK), took the cover off, locked it off, proved dead. The board cover then did not go back on my install bay until I had finished the testing that required access to it. For the other section (which in my case preceded the fault finding) there are three scenarios where you have to do safe isolation... two are isolating circuits in preparation for working on them... do not take the cover off the board for these.

 

[Elliott96]

The preferred method of testing continuity is R1+R2 (Method 1 in guidance note 3 - the reason will become apparent in a mo). Since you are testing a new installation, you should know whether there are parallel paths present. I took the CPC out the block and linked it to the line using an assessment centre provided Wago.

Polarity... Guidance Note 3 (familiarise yourself with it so if asked you can point the assessor to it) states you can prove polarity through a combination of visual inspection and R1+R2 testing.

What you're interested in is the Prospective Fault Current. It is acceptable to measure this from Line-Earth for each phase, take the highest value and double it. In reality you would, if your meter is capable, test between phases but in the AM2 it's acceptable to measure Line-Earth and double up the highest.

Just as you'll probably be advised to calculate Zs. In reality I like the security of measuring it but for the AM2 where time is short, you calculate it using the highest Ze value, but remember to add a remark to each line of the cert saying "Zs by calculation".

You will do two sections of safe isolation. I found it wasn't possible to remove the board cover with the lockout device on, so for the first stage (which is effectively proving your bay is safe for you to work on - this is done with the risk assessment section) I turned the board off (don't forget to ask if this is OK), took the cover off, locked it off, proved dead. The board cover then did not go back on my install bay until I had finished the testing that required access to it. For the other section (which in my case preceded the fault finding) there are three scenarios where you have to do safe isolation... two are isolating circuits in preparation for working on them... do not take the cover off the board for these.

Thanks alot mate!!

 

[buzzlightyear]

Thanks alot mate

the lady has been called a lot of things but not mate .

 

[AndyL]

What you're interested in is the Prospective Fault Current. It is acceptable to measure this from Line-Earth for each phase, take the highest value and double it. In reality you would, if your meter is capable, test between phases but in the AM2 it's acceptable to measure Line-Earth and double up the highes

You must also measure each line to neutral, double the highest of the readings