Another Pair of Eyes would be appreciated

[oharaf]

Hi folks, NAPIT on Friday, have been testing the installation again today to be absolutely certain of a smooth passage.

I would really really appreciate it in anyone would cast their eyes over these test results.

As far as I can see all checks out okay, but another opinion or 7 never goes amiss

Thanks in advance

Untitled

• oharaf
• 24 Sep 2008
• 1

 

[GaryMo]

1.29ohms Ze/Zs at this board, is that correct?

This isn't a board you've installed is it? Existing installation?

Your max Zs figure are wrong - 7.67ohms for a B6 60898 and 1.44ohms for a B32 60898.

 

[Spark123]

High Ze.
Max Zs for a B32 is 1.44 ohms. Max Zs for a B6 is 7.67 ohms, no RCD for utility room and lighting circuits?
Arguably the Zs for a circuit protected by a 30mA RCD can be up to 1667 ohms. Why the differing RCD times?

 

[ricicle]

Why no RCD/RCBO test results for utility room sockets (first line) ?

Are these socket circuits on RCBOs or RCD as the BS numbers will be wrong if they are RCBO.

 

[ricicle]

Too slow

 

[GaryMo]

Why the differing RCD times?

Good point. It needs to be tested in isolation so same figure for each final circuit being protected by it.

 

[Hann]

Not sure if it's required on this form (mine are different) but do you not need to put in R2 values for the main equipotential bonding conductors?

Looks very neat!

Good luck

 

[ericmark]

How do you get a Zs reading less than Ze?
Eric

 

[holmslaw]

..

 

[GaryMo]

r2 value for way 8 upstairs sockets seems high. I would expect around 1.08ohms.
Poor connections at socket outlets?

 

[GaryMo]

Your Li readings do not hang together, have you made a mistake on Ze (board) should it be 0.29 rather than 1.29? Also remember the max Li must be less then 80% (or is it 75%) of the maximum permitted - at the moment your well over for the 32A circuits.

It's 80%
All his values for 32A circuits are much lower, not over. Max Zs 1.44ohms, 80% corrected to 1.15ohms. No 32A circuits have Zs values higher than 1.15ohms.

 

[Spark123]

How do you get a Zs reading less than Ze?
Eric

It is possible to have a lower Zs than Ze as the Zs is taken with the main protective bonding in place. Quite often is the case with TT systems.

 

[holmslaw]

..

 

[GaryMo]

For circuit No 1 he has recorded Ze 1.29 + R1 R2 of 0.27 = 1.56 total earth loop - its well over.

and a measured Zs of 0.28ohms - it's well under!

 

[Spark123]

Yeah, I was puzzling over that too. Probablility is his Ze figure is wrong, or if it isn't then he shouldn't have energized and got the DNO in to sort the Ze figure, assuming a TN system of course.