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.

 

[telectrix]

it does on my castline certs.

 

[Electricalserv]

If the resistance between L/N are o.k and also between L/E you can edge your bets N/E will be aswell!

 

[ezzzekiel]

most certs also

 

[Octopus]

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.

If you've got any doubt that there may be stuff still plugged in I'd recommend that you test at 250v before moving on to 500v

 

[telectrix]

If the resistance between L/N are o.k and also between L/E you can edge your bets N/E will be aswell!

you hope. if no loads connected, L/N will read good. L/E will also read good even if you short N/E

 

[topquark]

If the resistance between L/N are o.k and also between L/E you can edge your bets N/E will be aswell!

Cobblers, well known for making shoes.

 

[Electricalserv]

Cobblers, well known for making shoes.

Thanks mate :49:hahaha. pardon my french that comment was rubbish. If anything its more likely going to be a fault between either L/E & N/E

 

[telectrix]

earth leakage faults are always between L/E or N/E.

 

[topquark]

Thanks mate :49:hahaha. pardon my french that comment was rubbish. If anything its more likely going to be a fault between either L/E & N/E

Quit digging the hole

 

[telectrix]

well, there i was , diggin that hole , hole in the ground, so big and round and deep it was. it's not there now, the ground's all flat, and beneath it is the bloke in the bowler hat. ( good place for LABC )

 

[olsonn]

Well I took the advice offered and disconnected both ends of the ring at the board. Put the L N and CPC from one end in to seperate choc blocks and tested using the other end. Tested between N and CPC and got 9.06, then tested between L and CPC and got 9.06 not great but a pass. Problem is I tested between L and N and got 0.00.


What am I doing wrong, or am I doing right and the circuit is wrong??

 

[telectrix]

are you sure that there are no loads connected, FCUs with neons, someting plugged in?????

 

[topquark]

Well I took the advice offered and disconnected both ends of the ring at the board. Put the L N and CPC from one end in to seperate choc blocks and tested using the other end. Tested between N and CPC and got 9.06, then tested between L and CPC and got 9.06 not great but a pass. Problem is I tested between L and N and got 0.00.


What am I doing wrong, or am I doing right and the circuit is wrong??

9.06 What? Megohms?

 

[olsonn]

Yes Megohms

 

[Benn]

This is what I do......

First make sure all appliances are unplugged, any fuse spurs turned off (this would give you a 0.26ish result, from reading between the neon)

One crocodile clip on both live conductors, the other on the Neutral conductors. Test. Hopefully >99.9

Repeat test for Live/Earth and Neutral/Earth.

Done. Although you could save time, by doing as what someone said above, using the screw in the MCB, and the busbars. If your really special you can IR test the whole installation at once. Making extra sure, you disconnect any equipment suspect to high voltages.