NIEIC inspection

[tom-the-sparky]

Hello everybody

Ive got my niceic inspection soon. On my recent fuse board change and test i completed Zs tests for each circuit but only calculated R1 + R2 (apart from the ring mains) IS THIS OK? Also if anyone has had the niceic guy come out, any words of warning?

Thanks

 

[AlanWirral]

If you did the Z's why didn't you do the R1 + R2's at the same time?

 

[Sintra]

You MUST test R1 + R2 or R2 at every point on every circuit. This test can not be calculated.


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[Ponty Massive]

How did you calculate R1+R2, did you measure the Ze then measure the Zs and take one from the other?

 

[tom-the-sparky]

Yep took a direct Zs measurement on each circuit and a Ze at the board and took one away from tother!!

 

[olly w]

You MUST test R1 + R2 or R2 at every point on every circuit. This test can not be calculated.

At every point on every circuit? are you sure it's not just the furthest point on every circuit?

 

[Des 56]

At every point on every circuit? are you sure it's not just the furthest point on every circuit?

If its a board change only
No requirement for Zs throughout the circuits,a reading at the extremity of the circuits is ok
I would also do a loop test at all the sockets if possible as well as continuity of the ring

 

[waynie2010]

i usually calculate R1+R2 on existing circuits too (except on ring circuits) and only measure it if its a new circuit. I also am looking into NICEIC enrolement soon and would like to know the assessors views on this so plz post the outcome,
cheers,
wayne

 

[WayneL]

Yep took a direct Zs measurement on each circuit and a Ze at the board and took one away from tother!!

Why?

Why did you want to know what R1 + R2 was?

 

[WayneL]

i usually calculate R1+R2 on existing circuits too (except on ring circuits) and only measure it if its a new circuit. I also am looking into NICEIC enrolement soon and would like to know the assessors views on this so plz post the outcome,
cheers,
wayne

If he's any good, he'll ask you what possible use a 'calculated' R1 + R2 measurement was to anyone.

 

[IQ Electrical]

Why?

Why did you want to know what R1 + R2 was?

Because he was following the great myth that states "thou shalt have a value for R1+R2 but I'm not sure why"

 

[Spudnik]

Must admit chaps, there is no reason not to measure R1+R2 on a CU change.

This would then go towards ensuring the cpc is continuous throughout the circuit, which a Zs measurement would not.

 

[WayneL]

Must admit chaps, there is no reason not to measure R1+R2 on a CU change.

This would then go towards ensuring the cpc is continuous throughout the circuit, which a Zs measurement would not.

I agree, Jason - measure it. Your cables are already disconnected etc etc. so why not.

A calculated R1 + R2 is as much use as a chocolate teapot - what does it tell you? Nothing.

 

[Guest123]

You mention to your assessor that you calculate R1+R2 from Zs-Ze, and he'll explain why this is no good.....on your re-assessment!!

 

[telectrix]

good post Lenny, but would be ok IMO to measure R1+R2 , and calculate Zs?

 

[Smugley]

It's okay to calculate Zs based on measured Ze and measured R1+R2. But only just okay!

Measuring Zs aswell makes me feel I have completely tested the installation. Remember that Ze is measured before the CU and R1+R2 is measured after it. Measuring Zs directly at the extremities of each radial and at least one point on each ring is the only test that includes any possible poor connections, high resistance joints etc that may lurk within the board.

 

[Guest123]

It's okay to calculate Zs based on measured Ze and measured R1+R2. But only just okay!

Measuring Zs aswell makes me feel I have completely tested the installation. Remember that Ze is measured before the CU and R1+R2 is measured after it. Measuring Zs directly at the extremities of each radial and at least one point on each ring is the only test that includes any possible poor connections, high resistance joints etc that may lurk within the board.

Agreed.

It is the only real test of a full circuit and all it's components.

 

[mark scotia]

Gentlemen

The correct method which is accepted/NIC guidance is to measure your r1 + r2 and from this you would calculate your Zs with the following equation Zs= (r1+r2)x1.2 + Ze, the reason being to verify polarity and most importantly it gives an accurate reading where your direct Zs measurement incorporates parrallel paths.

Hope this clears it.

 

[IQ Electrical]

Gentlemen

The correct method which is accepted/NIC guidance is to measure your r1 + r2 and from this you would calculate your Zs with the following equation Zs= (r1+r2)x1.2 + Ze, the reason being to verify polarity and most importantly it gives an accurate reading where your direct Zs measurement incorporates parrallel paths.

Hope this clears it.

The correct method?

Please post a reference for this 'correct method' I'm intrigued!

 

[Guest123]

Gentlemen

The correct method which is accepted/NIC guidance is to measure your r1 + r2 and from this you would calculate your Zs with the following equation Zs= (r1+r2)x1.2 + Ze, the reason being to verify polarity and most importantly it gives an accurate reading where your direct Zs measurement incorporates parrallel paths.

Hope this clears it.

The correct values are R1+R2 not r1+r2, these are two very different beings.

Also a measured Zs under normal service conditions will be a more accurate reflection of the situation as the parallell paths that exist will be included as they are in normal service conditions anyway. You will also gain a truer reflection of prospective earth fault currents.



This is why for those that do it, you CANNOT calculate R1+R2 from a measured Zs reading.