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Thanks did not know that, sounds crazy to me but those standards writers must know that they're doing!The insulation resistance for the entire installation in parallel must meet the minimum requirements of BS7671
Discuss Help needed with understanding IR in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
Thanks did not know that, sounds crazy to me but those standards writers must know that they're doing!The insulation resistance for the entire installation in parallel must meet the minimum requirements of BS7671
No problem. Strangely it seems to be a commonly misunderstood part of the Regulations although the same or similar Regulations have persisted through the various Editions.Thanks did not know that, sounds crazy to me but those standards writers must know that they're doing!
Yes indeed there isn't a minimum value defined for periodic inspection and testing.The 1Mohm requirement is actually for initial verification but stands to reason that it maybe, can used as a guide figure for carrying out an EICR
No problem. Strangely it seems to be a commonly misunderstood part of the Regulations although the same or similar Regulations have persisted through the various Editions.
I either record it against an entry for meter tails or for the relevant distribution circuit, or simply list the figure alongside every box.Unless I'm missing something is it because there is nowhere to record this value on the standard forms?
Unless you had a good feel for the results, and was concerned, why would you calculate it other than to put it in a result box on the form.
Really hoping there isn't a box I've been missing.
Thank goodness somebody commented!Firstly I presume you meant one Megohm (one million Ohms) as opposed to one Ohm.
Secondly the minimum values in the Regulations are for the entire installation (i.e. after you have done your calculation if you don't measure the whole installation in one go). (For a larger installation it can be subdivided.)
You wrote 1mohm which is 0.001 ohm not 1 M ohm! Yes we all know what you meant, but it is important to get units correct. In this case your unit was 1000,000,000 times smaller that the 1M ohm.As above you can't accept a lower value than 1mohm on any part of the installation whether combined or not. If you measure 20 circuits and get 0.1mohm combined that could be a fault on one circuit.
However if you break it down and they are all 1.5mohm then that's classed as ok.
Really? I did not realise that. And then they recommend expensive Arc detection!Yes indeed there isn't a minimum value defined for periodic inspection and testing.
Reply to Help needed with understanding IR in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
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