Exceeding max adjusted Zs on a board change.

[polo1]

Testing during a board change, a RFC on a 32A 60898, with rcd protection, you find that the max Zs is exceeded by 0.1 ohms using the no trip setting on your mf tester
On the EIC do you -
A) simply record the actual measured value
B) record the actual measured value and note the position under comments on the installation
C) retest, bypassing the rcd, on the Hi setting of the tester and record the revised value
D) change the ocpd to a lower value to achieve compliance with max Zs
E) do something different?

There's a round of drinks riding on this, so think carefully!

 

[Pete999]

C

 

[Leesparkykent]

C

 

[Wilko]

Easy one - go straight to the round of drinks isn't it ?

 

[Toneyz]

What is Ze and R1 + R2 added together

 

[Toneyz]

what type curve mcb ?

 

[The Ghost]

F. Tighten up some terminations. Switch the socket on and off a few times. Put the plug in and out a few times. Retest.

 

[Octopus]

G. massage the results (tin hat on)

 

[bigspark17]

A. Its on rcd so has additional protction max zs would be 1667 for 30mA rcd. No voltage drop or CCC issues then no problem.

 

[westward10]

It is a board change so not much you can do about the Zs so use the rcd for fault protection.

 

[polo1]

what type curve mcb ?

Sorry, B.

 

[Dave OCD]

It would have to be a very long RFC to have a non compliant Zs on a B32 Mcb, I suspect a high resistance connection lurking somewhere.

 

[westward10]

What is the Ze.

 

[polo1]

What is the Ze.

Ze 0.12; r1 0.54, rn 0.57, r2 0.89
R1+R2 0.67

 

[westward10]

Don't understand why the Zs is so high with those readings, ditch the rcd and test on high.

 

[Dave OCD]

The R1 & R2 must have been obtained at a spur on the RFC ? Regardless you have a Zs of 0.79 which is well under the max value for a 32a B type OCPD ?

 

[sparksburnout]

Ze 0.12; r1 0.54, rn 0.57, r2 0.89
R1+R2 0.67

RCD is messing up the meter readings.Just use the "by calculation" value, you don't have to measure it.

 

[Toneyz]

The R1 & R2 must have been obtained at a spur on the RFC ? Regardless you have a Zs of 0.79 which is well under the max value for a 32a B type OCPD ?

This is what I worked out to max to bs7671 on ocpd is 1.37 O.P. said +0.1 that gives 1.47 ????????? even at 80% I make it 1.09 + 0.1 =1.19

 

[DPG]

Test a few more times and take the best reading. Tin hat on and suitably bonded to the nearest window frame/radiator
Daz

 

[Octopus]

Ze 0.12; r1 0.54, rn 0.57, r2 0.89
R1+R2 0.67

Are you 100% sure about this?