A couple of AM2 questions.

[51ddo]

Hi all,

I'm new to this forum and its due to the fact that I have my AM2 exam this coming Monday.

I just have a few questions.

- Do I need to earth bond the cable tray?

- I know that the External Loop Impedance Test is on the incoming side of the installation, and that when testing i need to disconnect the main earth from the earth bar to test. The board is a 3 phase and so do I need to test between L1-N-E L2-N-E and L3-N-E or do I just take a reading between each phase and earth then obviously record the highest reading?

- For the insulation resistance testing am I right in thinking that;

- I need to disconnect the RCBO and the fly leads completely from the CU?

- Disconnect the Lighting circuit and remove the lamps so that i can test the circuit when operating the switches?

- Disconnect the incoming supply for the CU to my motor contactor and place in push in terminals so that I dont damage the contactor?

- Disconnect the load from the unswitched fused spur for the co2 detector?

Then do a global test for the rest of the circuits at the main switch? i.e L1-L2 L1-L3 L3-L1 L1-E L2-E L3-E? Or go across each circuit individually at the cu?

Anyway thats enough so far that I can think of. Any help would be fantastic!

Cheers,

Tom.

 

[Mmmbluenose]

No you do not need to bond the tray on the test.

For your Ze reading your main earth should be removed, but the test is between L1 + E, l2 + E and l3 + E and then you record the highest reading.

For your IR test I removed the sw at the light and put it on a connector, also I removed the CO2 detector not at the spur, I put cables in connectors and took the co2 down. Also I made sure the spur for the hearing system was off. The rcbo should be removed and replaced with a normal 32a mcb for this test. With all this done I tested the whole installation at the top of the main sw (with the main sw of) between phases, phases to earth, phases to neutral and then neutral to earth (10 tests).

This was how I was shown on my refresher and was how I did it last week and I passed. It may vary from other test centres but I doubt it

 

[retiredsparky]

Live testing: Test mains polarity and phase sequence. Test Ze: remove main earth test between L1 N +E, L2 N+E, L3 N +E record highest value as Ze.

Re connect main earth and test for PEFC and note the three readings then test for PSCC and note three readings. take the highest reading and double and record as the PFC. The IR test most of the equipment that needs to be removed should have male and female plugs with the RCBO you will need to disconnect the curly neutral and the functional earth. But remember to switch off the spur box on the ring as the switch as a neon, switch on the 25amp isolator, switch on the spur box for the heating, put all of the sliders across except the RCBO all mcbs on. Ten tests at load side of main switch don't for get lighting ring circuit and sy cable.