Wylex RCBO arc when Test pressed (no load)

[AndyPRK]

I got a new style wylex rcbo NHX

It has no load connected to it, only power.

When I press the Test button I can see an arc inside, from the side (dark room).
When in a CU you wouldn't normally see this.

Can anyone explain the reason. (I could understand it if there was a load) but I thought the test button wouldn't cause this.

Thanks.

 

[333rocky333]

Not sure if that range has a functional earth but,
When you pressed the test button you would have most likely put a load across the Line and Neutral.

 

[AndyPRK]

yes it has a functional earth and it was connected.


I thought it would connect a high value resistor across L&N (either side of the rcbo) to create an imballance and allow 15mA to flow.

 

[JohnW2]

yes it has a functional earth and it was connected. I thought it would connect a high value resistor across L&N (either side of the rcbo) to create an imballance and allow 15mA to flow.

As recently discussed, it's probably about 60mA for a 30mA device (3.9kΩ resistor)(just in case there is a nearly 30mA imbalance in the opposite direction/phase when you press the test button) - but, yes, I think that's the principle.

However, another factor is that the device has to generate a voltage to operate the electronics from the L and (N and/or E). If that happens on the load side of the device (I don't know) then operating the device would interupt that. I would have thought the current involved would be far too small to cause any arcing - but if there are (as there will be) capacitors knocking around the power generation circuit, maybe that could just about explain it.

Kind Regards, John.