funny reading mtf 1502/2

[leekemp85]

I have my elecsa assessment tommrrow the job I am showing is a loft extension and shower room.
on the shower circuit I have a Zs reading of 0.52 but the Ze is 0.06 and R1+R2 is 0.13
I though my tester was faulty so I had it calibrated and went back today to get the same readings

Is something that I could fail on???

 

[Darkwood]

Its a common question and get alot of new people confused you have parallel paths on your earth so its using more than one earth path in this case the water pipe to your shower is probably the parallel path which is bonded pretty good judging by the results, try withdrawing the shower cable from the terminals to test if you want a realistic result or when showing the elecsa guy simple explain why the result is so low, If he sees your understanding of this it usuallly goes in your favour.
As the earth in your cable is the one your testing its probably best to remove cable for the test then replace do this when the elecsa inspector is there and explain why you did it like this.

 

[Bulmer]

Wouldn't parallel paths give you alower Zs result?

 

[leekemp85]

that is what I thought Ze + R1+R2 =Zs so my reading should be 0.19. Not 0.52 but the reading is still ok with the regs, so I am hoping it will be ok.

 

[acvc]

Leekemp. The tables would suggest that if your shower circuit is in 6mm+2.5mm, then its length will be about 12m. If you've used 6mm+4mm then the length should be 16m. If, as is most likely you've used 10mm+4mm cable, then the tables say your circuit should be about 20m long. Does this correspond with what you've got?

 

[sparkswillfly]

what earthing have you got tncs tns and did you remove main bonding when taking your ze

 

[leekemp85]

I used 10mm +4mm it is around 20 m running through some insulation but its only a 8.5Kw shower

 

[acvc]

OK so at least you can rule out the R1R2 as the source of the problem. That's a good thing! The issue is with how you're testing. If you're testing with the shower cable connected to the shower, then you're higher result might be explained by the components of the shower itself becoming included in the test. It could be the same as doing a Zs at a socket with stuff plugged in on the socket circuit. I wouldn't worry about it for your assessment. As Darkwood wisely states, if you show the guy that you know how to test, how to check your results are reasonable, and that you know when there is an problematic reading, then you'll be fine.

 

[Darkwood]

Wouldn't parallel paths give you alower Zs result?

Yes you would i miss read il stand corrected on this one but if the Zs is higher is likely to be a termination slightly loose although it may not be loose enough to concern also the test probe may be been used on the termination screw and in showers amongst other fixtures the can have an anti-corrosion coating which is slightly resistive.

 

[sparkswillfly]

can you confirm correct ze test and resaults

 

[sivoodoo]

Hi leekemp85,

Did you pass? How did the assessment go?

 

[leekemp85]

It went very well, passed with an A. but I think I will buy a new tester before the next assessment (the funny readings gave me sleepless night's )

 

[sivoodoo]

Well done!! I have mine next week and I'm krapping myself!, what questions did the assessor ask you? What tests did he ask you to perform?