Help IR Testing on a ring final circuit

[olsonn]

I am trying to do some individual circuit testing ahead of my 2391 practical, but I am having a problem with final ring circuits. Radial circuits aren't a problem, but when you look in all the guidance including GN3 it only deals with lighting circuits. Do you have to join all 4 live ends together? I am obviously doing something wrong as the 3 step continuity of ring final circuits is, spot on as is the R1+R2, but I am getting 0.00 for IR.

 

[Octopus]

If you join all 4 ends together, by which I conclude you mean the ends of the live and neutral there's no wonder you get a 0.00 IR!

 

[telectrix]

yep. for IR testing, you need all the ends separating as you are measuring the integrity of the insulation. if you short the conductors out, you will read 0.

 

[i=p/u]

i asked my tudor about doing 2391 while i was doing level 3 and he steered me away

 

[olsonn]

obviously from the responses so fa,r I am doing it wrong, but what nobody has siad is how I should be doing it

 

[telectrix]

separate all ends. set meter to 500V. clip on L/ N. press test button. repeat for L/E and N/E. make sure nothing is plugged in first or be prepared to fork out for new pc, TV, etc.

 

[i=p/u]

just connect single cables like radial l-n,l-e,n-e its all continuous

 

[Des 56]

obviously from the responses so fa,r I am doing it wrong, but what nobody has siad is how I should be doing it

Would you care to give a step by step account of your procedure, so that comment can be made on your procedure, rather than people saying what should be done

 

[olsonn]

Not a problem Des. I carried out the 3 step continuity test and results were as expected ie: r1 + rn/4 and r1+r2/4. Then to do the IR test I used one end of the ring cable and connected my clips to the Line an Neutral, with the CPC cables unconnected. The other end of the cable was unconnected, with none of the conductors touching. As a precaution I always test at 250v first, a lesson I have learnt from this forum. When I tried to test, I got a reading of 0.00.

 

[telectrix]

it would appear that he's trying to perform an IR test with the conductors linked as for continuity.

 

[Electricalserv]

Simple...


Unplug all appliances and loads. test between the mcb screw terminal & neutral bar. Repeat between mcb screw terminal & earth bar.record results........ Simple your ring I/R test

 

[timo1]

Try youtube and type in insulation resistance there is a good vid on there which will make it easy for you.

 

[telectrix]

Simple...


Unplug all appliances and loads. test between the mcb screw terminal & neutral bar. Repeat between mcb screw terminal & earth bar.record results........ Simple your ring I/R test

and what about N/E ???

 

[Electricalserv]

and what about N/E ???

Plus N/E only reason I didn't say because it doesn't need recording!

 

[SirKit Breaker]

I will try to make it simple.

Disconnect BOTH legs Line/Neutral and earth, of the ring circuit from the Consumer unit.
Keep the legs seperate from each other.
Keep all the individual cores seperate from each other, so all conductors are not in contact with any of the others.
Now connect your meter to L and N on one end of the circuit, test
Repeat L and E
Repeat N and E

Test complete, it is just the same method as for a radial circuit, but you have 2 ends, so watch out that you dont touch the opposite end to the one you are testing on as it will energise with the Insulation resistance test voltage.

Hope this clears the air a bit for you. Buy Guidance note 3 if you haven't already got it, this shows step by step all the required test procedures with full instructions, and pictures, it is the testing bible.

Cheers.........Howard