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APPENDIX A
RESIDUAL CURRENT DEV
ICES (RCD’S)
Also known as Earth Leakage Protection systems an RCD is a protective device
that automatically disconnects the live conductors of a circuit when an earth
leakage current reaches a predetermined value.
Australian and International Standards detail when and where RCD’s are to be
used in electrical installations, but common practice in many countries is to use a
30mA RCD in general commercial applications. This is typically done because
30mA RCD’s are readily available and are used in domestic installations.
For Commercial installations, and for socket-outlets providing power to commercial
heating equipment (Toasters, Bains Marie, Grillers), 30mA RCD’s are typically
unsuitable unless they are protecting only one device. Higher rated RCD’s should
be considered if protecting multiple socket-outlets, giving appropriate consideration
to the type of equipment being protected.
AS/NZS3000 2.5.2 gives the following warnings that should have been taken into
consideration when an RCD circuit was installed.
To avoid unwanted tripping due to leakage currents and transient
disturbances, care should be taken to ensure that the sum of the leakage
currents of electrical equipment on the load side of an RCD is less than
1/3 of its rated residual current
.
To avoid excessive leakage current causing unwanted tripping where
socket-outlets are protected by one RCD having a rated residual current
not greater than 30mA, consideration should be given to the number of
socket-outlets protected and the nature of electrical equipment likely to
be connected to the socket-outlets.
Tubular elements (such as those used in this unit) reaching temperatures greater
than 110°C are subject to moisture absorption and therefore earth leakage current
generation. Should the installation and use of this unit trip an RCD the unit will
need to be run on a circuit without an RCD for approximately 30-60 minutes, after
which time the elements should have dried out and the machine should function
normally. If you are unable to locate a circuit without an RCD please contact your
supplier or contact Roband
®
or our Agent for alternative suggestions.
