Completing Zs box on schedule of test results

[Nicebloke]

When unable to carry out a Zs test on a lighting circuit (large/heavy chandelier type lighting), then the R1+R2 + Ze measurements are instead used and this is noted, but is it the norm to still write this value in the Zs box on the schedule of test results or just in the notes. I ask because technically a Zs test hasn't been conducted, and the R1+R2 + Ze calculated isn't necessarily going to be the same as an actual Zs test?

 

[Octopus]

If you've done a R1 + R2 why can't you do a Zs?

 

[ImpededLoop]

If you've done a R1 + R2 why can't you do a Zs?

Perhaps the chandelier was installed before there was a power supply to the building, so only dead tests were possible at that time.

 

[Leesparkykent]

yes you would still record the calculated result for Zs in the appropriate box as calculation is deemed an acceptable method.

 

[Octopus]

Perhaps the chandelier was installed before there was a power supply to the building, so only dead tests were possible at that time.

I did think this may be the case but most of those light fittings are class 1 and then your Kewtech adaptors do come in handy in such situations.........

 

[Des 56]

R1+R2 added to Ze is a worst case,a direct Zs may include parallel earth paths and would tend to make it lower,if the R1+R2 calculation is within limits,the true Zs will almost certainly make it better in the real world

 

[The Ghost]

So what's wrong with doing it at DB?

 

[Octopus]

So what's wrong with doing it at DB?

??????

 

[The Ghost]

Zs on the lighting cct at DB

 

[Octopus]

You lost me

 

[The Ghost]

Don't know what to say to help you there!

You lost me

 

[Octopus]

Just how you would do a Zs at the extremity of the lighting circuit at the DB?

 

[The Ghost]

Yep ok its got to be done at the furthes point, point taken, silly me.

 

[telectrix]

Just how you would do a Zs at the extremity of the lighting circuit at the DB?

you link L and E art the fitting, then measure the Zs at the DB as below:

View attachment 35542

 

[buzzlightyear]

is this for eicr or eic cert .

 

[Dave OCD]

You could also do it at the furthest switch from the DB ?

 

[Deleted member 26818]

Always find it wrong for a schedule of 'test' results to include calculated values.
To my mind, if a test is not conducted, then no value should be inserted into the box.

 

[LeeH]

When unable to carry out a Zs test on a lighting circuit (large/heavy chandelier type lighting), then the R1+R2 + Ze measurements are instead used and this is noted, but is it the norm to still write this value in the Zs box on the schedule of test results or just in the notes. I ask because technically a Zs test hasn't been conducted, and the R1+R2 + Ze calculated isn't necessarily going to be the same as an actual Zs test?

It has been tested, you have tested the external and internal loop. And added them together.

Maybe not ideal and to everybody's taste, but a test all the same.

 

[Deleted member 26818]

To be honest, I struggle to understand why anyone would bother to do such a thing.
Why would anyone want to calculate a value, knowing full well that it is very likely to be inaccurate, then record it as if a test had been conducted?
What is the point, what purpose does it serve?

 

[Dave the spark]

To be honest, I struggle to understand why anyone would bother to do such a thing.
Why would anyone want to calculate a value, knowing full well that it is very likely to be inaccurate, then record it as if a test had been conducted?
What is the point, what purpose does it serve?

Surely you just have to prove compliance with the permitted maximum values? By calculating it you're giving a worst case scenario, if it complies then all well and good. You're going to meet disconnection times regardless of noting the measured value or the calculated value.

It's not something I tend to do personally but I can see why people do it.