Zs reading in workshop

[PHS]

The last problem I have to finish the paperwork is that I have a Zs @DB reading from the house CU of 0.31ohms with a Ipf @ DB of 0.74 ka.
On the test result sheet for the workshop, which has a 40amp rcd, 2 x 20amp socket radials and a 6amp lighting curcuit, what figures do I use to add to the R1/R2 readings to get me the Zs figures needed?
and what figures go into the Zs and Ipf @ DB box on the sheet for the workshop.
If what I have writen doesn't make sence please say and I will try to explain better.

I am thinking its the same figures as the house
Cheers guys

 

[trev]

Ze +((R1+R2) for the feed to the workshop) = Zdb at the workshop
Zdb at the workshop + ((R1+R2) for the workshop circuits) = Zs for the circuits
Assuming the above Zs cannot be measured, also assuming that I'm reading your question correctly.

 

[PHS]

The workshop is fed from a 40amp non protected breaker in the house and I got an (R1+R2) reading of 0.15 from the feed into the workshop (if it was just feeding a socket for instance as a radial)
but it is feeding a new cu in the workshop.
Do I add the 0.15 to the 0.31 to get the figure needed to add to the R1+R2 readings of the radials and lighting circuit is what I'm getting at really or am I missing the point altogether?

 

[trev]

I'm at a loss to understand what bit of #2 you don't get mate, let me know and I'll try to explain it a bit more clearly.

 

[telectrix]

The workshop is fed from a 40amp non protected breaker in the house and I got an (R1+R2) reading of 0.15 from the feed into the workshop (if it was just feeding a socket for instance as a radial)
but it is feeding a new cu in the workshop.
Do I add the 0.15 to the 0.31 to get the figure needed .


yes, just as trev said.

 

[trev]

Measuring it would be far easier.

 

[PHS]

All done cheers

 

[trev]

So, by measurement or by calculation?
Either way it's not that hard is it? It sometimes seems that way when you've been looking at it and disappearing up your own backside though

 

[PHS]

So, by measurement or by calculation?
Either way it's not that hard is it? It sometimes seems that way when you've been looking at it and disappearing up your own backside though

Measurement in the end. Was just not thinking straight, to many things in my head!!

 

[trev]

Measurement in the end. Was just not thinking straight, to many things in my head!!

Sometimes you can look at something for too long and because your head is up your backside you just go round and round in circles mate. We've all been there and done that.

 

[Engineer54]

Measurement in the end. Was just not thinking straight, to many things in my head!!

I'm at a loss as to why you would even contemplate using calculation over measurement?? So come on tell us what was your final measured Zdb (Zs) value, compared to you're calculated 0.46 value??

 

[PHS]

The measurement came in at 0.38