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Earth leakage relay protective device

Pyro

Due to a change in earthing arrangement, I need to add overall earth leakage protection to a 400 A LV distribution board. The board has an incoming switch disconnector, with overcurrent protection provided by fuses upstream. I can't work out if it would be acceptable for the earth leakage relay to shunt-trip the switch disconnector, or whether I need to replace it with an MCCB. Earth leakage would not implicitly mean that the protective device was interrupting fault current, requiring the CB, but depending on the fault then it could be... Any advice appreciated, ta!

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  • +1

    Only if the disconnector is rated to open under the  current that may be flowing when at the time - not always clear, as a switch disconnector is generally not rated for breaking against a heavy fault - does it have arc chutes for example ?

    However, if the power will be removed in the case of a short circuit fault by something else, the upstream fuse or a breaker  suitable for the PSSC, then you may argue that the switch disconnector is protected by that, and it is acceptable for the switch disconnector to be sacrificed then, as the back-up device does the ADS.

    Generally, to have the earth fault detection operate a proper breaker is vastly preferred.

    Mike

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  • +1

    Only if the disconnector is rated to open under the  current that may be flowing when at the time - not always clear, as a switch disconnector is generally not rated for breaking against a heavy fault - does it have arc chutes for example ?

    However, if the power will be removed in the case of a short circuit fault by something else, the upstream fuse or a breaker  suitable for the PSSC, then you may argue that the switch disconnector is protected by that, and it is acceptable for the switch disconnector to be sacrificed then, as the back-up device does the ADS.

    Generally, to have the earth fault detection operate a proper breaker is vastly preferred.

    Mike

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