C
Crosswire
...anything wrong with using an RCD to meet disconnection times?
why does this circuit not meet the correct Zs value ?
poor design ? undersized earthing ? too long a cable run ?
i'm already frothing at the mouth in fury.
;-)
Could be any or all of the above..But purely hypothetically speaking, doesn't providing an RCD on the circuit make the max Zs requirements redundant?
NO, it doesn't make ADS requirements redundant!! RCD's are classified as Additional protection, NOT the ONLY protection!!!
well (and i hate to say it).....but yes it does......Could be any or all of the above..But purely hypothetically speaking, doesn't providing an RCD on the circuit make the max Zs requirements redundant?
If you take this argument to its logical conclusion then we should be able to disregard all max Zs calculations in 7671 and assume that all circuits have a max Zs of 1667 Ohms if protected by an RCD
Max Zs is there to ensure that the resistance to earth is low enough to allow the circuit breaker to operate and disconnect the circuit accordingly (and high enough so it doesnt knacker the MCB) As stated above an RCD is there as additional protection. Dont mix up disconnection times (MCB) and tripping times(RCD), they are different