AM2 Questions Testing

[jaydub]

Got my AM2 coming up on Monday, when conducting an R1 + R2 test on the s-plan heating system, would you connect the line and cpc in the DB, switch the FCU on then test between L&CPC at every point on the heating system and then note down your highest reading?

Secondly, how would you go about ins-res testing the s-plan? Do you test it in two parts, DB to the FCU and then secondly the switched side of the FCU to all parts of the heating system?

If someone could clarify that it would be a dream come true.

 

[Dobes_88]

From what I can recall when I did my AM2 (few years ago) you only test up until the spur - could be very wrong though! Did you do the pre-AM2 day which they normally advise you on what to do as procedures at test centres can vary?

 

[jaydub]

Yes I did attend the AM2 refresher day but there was so much content to take in and I must admit that it didn't really occur to me at the time!

 

[Zdb]

You only test up to the spur as Jamie said.

 

[westward10]

I would isolate the cpc at one end to eliminate parallel paths which will then give a true reading.

 

[jaydub]

Thanks for the replies, yes I will take the CPC out of the earth bar for the test, I had just read so many differing opinions across various forums about the s-plan testing procedure.

Secondly, when conducting an Ins-Res test on the 3 phase motor circuit, would you disconnect the cables from both sides of the starter and join in terminal blocks to bypass it? Am i right in thinking that the starter is a sensitive piece of equipment? Plus the contactor would be open anyway...

 

[westward10]

If it is a standard DOL starter with no electronics it wouldn't be, in my opinion sensitive to IR tests. You could bypass it or hold it closed by some means but my ways may not be the ways of the AM2 eyes. But yes with no power the contactor will not be energised to fully test the circuit.

 

[Pete999]

You will be testing the fixed wiring up to the spur imo.

 

[Jay Sparks]

Also remember to do the (R1 + Rn) tests on the ring final and write the result either at the top of the Schedule of test results sheet, or in the comments section on the end. Apprentices have failed for not doing this. With regards to the DOL and IR test, some centers will require you to test up to the contatcor, then from the other side to the motor. Some may provide links that will bypass it.

Jay

 

[westward10]

So the starter is not IR tested?

 

[jaydub]

Thanks jay sparks

 

[Jay Sparks]

So the starter is not IR tested?

Only going by what apprentices have told me but they IR test to the supply side of the DOL then IR from the load side. And some centres expect them to link out the contactor so they can test the lot in one go.

Jay

 

[jaydub]

I GN3 it says to power up the system once dead testing has been done, then carry out the earth fault loop testing including Ze and Zs tests.

Now, in my mind it would make more sense to perform the Ze test before switching the power on, as you will need the main earth disconnected from the board and I'd personally like to know for a fact that the installation has a good earth fault path before energising it, am I wrong here? For the purposes of the AM2 the supply is TNCS.

 

[Richard Burns]

External earth fault loop impedance (Ze)should be confirmed before power is applied to the final circuits. However it is necessary to have power to the incoming side of the main switch in order to be able to perform the test.
The test rig in exam situations often has a secondary power connection (plug and socket) before the main switch; with the main switch OFF (open) this connection should be powered up in order to test Ze.
It would be dangerous (and a fail) to test Ze and disconnect the incoming earth if the final circuits were powered, though it would be possible to test with all circuit breakers off and the main switch closed, but it is not recommended.

 

[jaydub]

Thanks Richard

Sb8389 what do you disagree with?