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Compliance with 411.3.3 RCDs on Socket Outlets

I have a scenario where we have a standard circuit arrangement. 32A Ring Circuit feeding a number of socket outlets.  An RCBO of 32A/30mA is specified at the DB.  However the outlets also have 10mA RCD's at each outlet.    Whilst there may be issues around nuisance tripping. ITs been suggested that we remove the RCBO and use a standard 32A Type B MCB at the DB.

 IMO this means the circuit would not have RCD protection,  and only the outlets ( or appliance plugged into an outlet would be protected).  So the question I have is would a 32A MCB Ring circuit when serving this arrangement be compliant with the regs?

One concern I have with this is that should an outlet ever be changed for a normal 13A SSO, then the circuit again would be non compliant.   And that in the event of an earth fault (depending on the ZS) it may not achieve the necessary disconnection times for a ring circuit. 

 

Thoughts? 

Parents
  • I would favour RCD/RCBO protection at the origin of the circuit AND use of socket outlets with inbuilt RCD protection.

    The 10ma protection gives a greater degree of protection to a person handling a defective appliance.

    Depending on circumstances, then 30ma protection is probably still required for the circuit.

    RCDs do not have a great record of reliability, and two levels of protection give an extra safety factor. There is a chance that both RCDs may trip, but that in my view is a price worth paying.

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  • I would favour RCD/RCBO protection at the origin of the circuit AND use of socket outlets with inbuilt RCD protection.

    The 10ma protection gives a greater degree of protection to a person handling a defective appliance.

    Depending on circumstances, then 30ma protection is probably still required for the circuit.

    RCDs do not have a great record of reliability, and two levels of protection give an extra safety factor. There is a chance that both RCDs may trip, but that in my view is a price worth paying.

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