Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 82 replies
  • Subscribers 32 subscribers
  • Views 9441 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Can Zs at DB ever be less than the Zs of the feeding circuit?

Former Community Member
Former Community Member
I am reviewing an EICR recently issued for a building with several Distribution Boards feeding sub-Distribution Boards.

I have noted that in some instances, the figure recorded for 'Zs at this board' is significantly less than the Maximum Measured Zs for the circuit recorded on the feeding DB.

e.g. DB FF4 is recorded as being fed from DB FF1.  The feeding circuit to DB FF4 is recorded as having a Maximum measured Zs of 0.4 Ohm, but the 'Zs at this board' for FF4 is recorded as 0.05 Ohm - which is less than the 'Zs at this board' recorded for FF1 (0.08 Ohm) - and which, is in fact, in turn itself less than the 'Maximum measured Zs' for the circuit feeding it.  Can this be true or are there errors in the report?  I thought that cascaded Zs can only get larger due to the added impedance of the feeding circuits? This is not my primary area of expertise, but I am concerned that the EICR is being used to justify the upgrade of several circuits which have passed previous inspections with no problem (hope the resolution of the extracts from the EICR below are sufficient resolution to read)...

248ee514524cf5398885518b2007a96a-huge-image.png


b952bae4d3b1f32d959d675c6ede9a16-huge-image.png
05733e3016557d58306811936bac5e50-huge-image.png


Many thanks if anyone is able to confirm my concerns or otherwise put me straight...
Parents
  • Former Community Member
    0 Former Community Member
    Peter S3:


    "I assume it’s the rubbish software used for this forum, both reports have disappeared.


    No, sorry, I removed the attachments as I realised that the redacting was not 100%.  Since it is looking like the trustees will need to be seeking resolution on this, I need to be careful.

    I may re-post once I have double-checked the redaction.


    Which raises the question: what would folks advise should be my next step?  The trustees have no confidence to invite the original contractor to repeat/correct the report, and it does not appear that he is NICEIC approved (I was not involved in his initial selection).  I am considering to ask whether he wishes to retract his report or allow us to submit it for independent review - with potential resulting claim through legal channels.



     


    Hi Peter, fair point thanks for letting us know. It is not an easy position to be in. Do you know if there have been any alterations between the previous and current EICR? 


    Would some anonymous pics of similar DBs and the C2 areas be available? 


Reply
  • Former Community Member
    0 Former Community Member
    Peter S3:


    "I assume it’s the rubbish software used for this forum, both reports have disappeared.


    No, sorry, I removed the attachments as I realised that the redacting was not 100%.  Since it is looking like the trustees will need to be seeking resolution on this, I need to be careful.

    I may re-post once I have double-checked the redaction.


    Which raises the question: what would folks advise should be my next step?  The trustees have no confidence to invite the original contractor to repeat/correct the report, and it does not appear that he is NICEIC approved (I was not involved in his initial selection).  I am considering to ask whether he wishes to retract his report or allow us to submit it for independent review - with potential resulting claim through legal channels.



     


    Hi Peter, fair point thanks for letting us know. It is not an easy position to be in. Do you know if there have been any alterations between the previous and current EICR? 


    Would some anonymous pics of similar DBs and the C2 areas be available? 


Children
No Data

Community Rules & Guidelines