Am2 safe isolation advice

[Gavin John Hyde]

I have never done the AM2 myself but have worked with guys and one girl who have, it is sometimes a mystery to me how some of them pass it and others do not, as ultimately i think it comes down to dealing with pressure and the clock in the back of their minds. Its normally silly little things that they would never normally do that causes them to fail. I wish you best of luck for doing it though and hopefully you pass.

 

[buzzlightyear]

before you do a am2, the tutors will go through every thing with the students to show them how to apply themselves on testing.

 

[I2C]

With 10 steps, I'm presuming it's a three-phase board? I'll go through the steps I'd take to provide some food for thought:

1. Identify the circuit you will be working on and which corresponding isolator it represents. (In this case however, I'll presume they have asked for the whole board to be isolated).
2. Ask for permission to isolate, mentioning which circuits will be effected (consider elevators, fire-alarms, lighting, etc) and specify how long until everything is turned on again.
3. Make sure that you appropriately off-load the board (the main-switch should be last).
4. Depending on the board, you should either:
   - Lock-off and tag-out, before removing the boards cover (it's preferable but not always possible).
   - Remove the boards cover, then lock-off and tag-out.
5. Take your AVE (Approved Voltage Indicator to GS38) and perform checks to make sure it's fit for use (look and feel to confirm the condition of body, condition of leads, tips & finger guards compliant, no modifications, fused, etc).
6. Prove that your AVE is functional by checking it against a known source, listening for the appropriate sounds and visually observing all indicator lights (ideally use a proving-unit for this task, otherwise a known-supply is acceptable).
7. Complete the 10-step safe-isolation procedure in this order (checks between the safest conductors first and most dangerous conductors last):
   - Earth to Neutral
   - Earth to L1
   - Earth to L2
   - Earth to L3
   - Neutral to L1
   - Neutral to L2
   - Neutral to L3
   - L1 to L2
   - L2 to L3
   - L1 to L3
8. Re-prove that your AVE is still functional by checking it against a known source, listening for the appropriate sounds and visually observing all indicator lights (ideally use a proving-unit for this task, otherwise a known-supply is acceptable).
9. Let everyone know that the board has been safely isolated and work can commence. Also advise everyone that you are responsible for holding the key.

I hope this helps and gives you some food-for-thought.

 

[Deleted member 26818]

Never known it as being 10 step.
Always known it as 12 step.

 

[I2C]

Never known it as being 10 step.
Always known it as 12 step.

I'm intrigued Spinlondon, what does the 12 step involve? I'm always responsive to suggestions which improve health & safety in addition to the standard practices.

This was the way I was personally taught in college, the 10 steps only apply to the combination of the conductors (E-N, E-L1, E-L2, E-L3, N-L1, N-L2, N-L3, L1-L2, L2-L3, L1-L3) but doesn't include the other considerations (such as lock-off & tag out, proving AVI before and after, asking for permission, etc) as previously mentioned.

 

[Pat H]

If they felt you were unsafe they will have stopped you then ant there. If you completed till the end then there should have been no safety issues.

 

[Deleted member 26818]

I'm intrigued Spinlondon, what does the 12 step involve? I'm always responsive to suggestions which improve health & safety in addition to the standard practices.

This was the way I was personally taught in college, the 10 steps only apply to the combination of the conductors (E-N, E-L1, E-L2, E-L3, N-L1, N-L2, N-L3, L1-L2, L2-L3, L1-L3) but doesn't include the other considerations (such as lock-off & tag out, proving AVI before and after, asking for permission, etc) as previously mentioned.

The two checks to prove the voltage tester, before and after.

 

[I2C]

The two checks to prove the voltage tester, before and after.

Completely agree with you Spinlondon! Checking the functionality of the AVE is often forgotten, while extremely important.

The "10 steps" I mentioned only refer to the number of conductor-combinations tested, rather than every step taken during a proper safe-isolation procedure. It's a great method for students (which I used myself during college) to count each combination tested to ensure completeness, providing all other steps have been followed.

Interestingly, I've met many domestic-electricians who don't perform safe-isolation correctly. Most recently, an experienced electrician hilariously told me not to test between line-CPC or neutral-CPC because it will trip the RCD. I re-informed him that the AVI that I was using has an internal-resistance of 200,000 Ohms (as per the datasheet), and basic Ohm's Law calculates the resulting current to be less than 2mA which is incapable of tripping a 30mA RCD.