IR test and Loop impedance test

[Elitepm]

Evening all

I need some answers (and quick please!).

1. I have a lighting circuit with 4 X low voltage down lighters.
Q- Do I have to remove trannys from the circuit as well as lamps? I've taken readings for N- CPC and P-CPC which are acceptable but P-N is completely diffent!? Help!

2. In the same room I have installed a new ceiling. I have connected to the old ceiling rose and daisy-chained off with 1.5T&E to each fitting. The CPC is connected all the way through back to the rose but is not connected to the trannys.
Question - How do I perform an Earth Loop Impedance test on this circuit?

3. In the bathroom all the pipework is plastic including heating. I have 4 LV down lighters and one 1 shaver socket. There is also a metal bath and a plumbed towel warmer. i have wired it to a 6amp MCB and connected it to the RCD side of the CU. Q - Do I still need supplementary bonding.

I'm using this job as one of my assessment jobs for the NICEIC Domestic Installer Scheme.

Thanks guys in anticipation

Brian

 

[oharaf]

Yep, get the trannys out the circuit.

Loop Impedance from the ceiling rose I think!!! BAS? RF?

 

[Elitepm]

The ceiling rose is now buried in the new false ceiling! But I have extended the CPC to each fitting withouit connecting it.
Sorry I don't understand BAS? RF?

 

[GaryMo]

IR testing should have been performed before connecting transformers.
Measure R1+R2 values at each point, switches included and record the highest value. This will also confirm polarity.
You can, if you choose to, measure earth fault loop impedance at the point where R1+R2 was the highest. Another method would be to calculate it Zs=Ze+(R1+R2). Never back calculate R1+R2 though and make sure Ze is measured with the installation isolated and all outgoing earthing and bonding conductors removed.

 

[Elitepm]

Cheers for that chaps
But do I need any bonding in this bathroom?

 

[GaryMo]

Cheers for that chaps
But do I need any bonding in this bathroom?

You'll need to install supplementary bonding conductors between each circuit within Zones 1 to 3.

 

[Elitepm]

Even though I've got plastic pipework and RCD protection?

 

[GaryMo]

Yes, it's a requirement of the (current) 16th edition.

 

[Elitepm]

Oh yea, I forgot that the 17th edition dosen't start til July
Do you think that my assessor will ask me to bond everything? Or is the installation compliant with 17th?

 

[GaryMo]

Oh yea, I forgot that the 17th edition dosen't start til July
Do you think that my assessor will ask me to bond everything? Or is the installation compliant with 17th?

Is it compliant with the current regulations?

 

[Elitepm]

ok i understand

 

[sm1thson]

Oh yea, I forgot that the 17th edition dosen't start til July

Is it compliant with the current regulations?

i thought as of the start of the year 16th and 17th were both current? and that come next month 16 is old and 17th is current, or is it an overnight change?

 

[Spark123]

All installations designed after 1st July need to be designed to the 17th edition.

Yep, get the trannys out the circuit.

Loop Impedance from the ceiling rose I think!!! BAS? RF?

EFLI at the furthest part of the circuit, probably at the transformers but could be at a switch. Or has been mentioned, use Zs=Ze+(R1+R2) method. Record the max value as your measured value.

The ceiling rose is now buried in the new false ceiling! But I have extended the CPC to each fitting withouit connecting it.
Sorry I don't understand BAS? RF?

All non permanent connections should be accessable for inspection and testing.
BAS and RF are 2 members here.

Cheers for that chaps
But do I need any bonding in this bathroom?

You'll need to install supplementary bonding conductors between each circuit within Zones 1 to 3.

Apart from the lighting circuit, are there any other circuits in the zones of the locations? SELV lights do not need to be bonded. Is the bath in contact with a building metal structure?

 

[ban-all-sheds]

The ceiling rose is now buried in the new false ceiling!

Your NICEIC assessor won't like that.

As for 16th/17th, right now you can work to either, but you can't cherry-pick bits of each. If you go for the 17th then the supplementary equipotential bonding requirements are relaxed provided:
i)All the final circuits within of the location meet the requirements for automatic disconnection.
ii)All the final circuits of the location are RCD protected.
iii)All extraneous conductive parts of the location are effectively connected to the protective equipotential bonding.

I think that's it. Don't have a copy of the 17th - still not sure if I might not just declare UDI in relation to it...

 

[DIYANIMAL]

inaccessable joints....big no no