3 Pole ELCB

[kousikpatra]

I want to use an ELCB in a thre phase three wire system.
As only two or four pole ELCB's are available here, can I use a 4P ELCB with any one pole unwired? Will it trip in case of earth fault?

 

[Skogsgurra]

ELCB = Earth Leakage Circuit Breaker? Aka RCD.

As long as the current through the sense coil is balanced, it won't trip. If the leakage current does not return through the sense coil (and exceeds trip limit), it trips. RCDs with three phases and N (four pole) are used in TN-S installations, but should be possible to use in TN-C systems (mustn't return PE through RCD, though). Where in the World are you? What does local code say?

Gunnar Englund

http://www.gke.org

 

[panelman]

As Skogs says they will work fine with only the three phases connected but the test function normally works by bleeding some mA from one phase to neutral so without the neatral connection the test function will not work. When we install them we connect an earth to the 4th pole to give the test mA somewhere to go.