Earth Fault at 240V Single Phase System

[solzinal]

Hi... I am Shamsul from Malaysia

I have a question regarding to earth fault current if occur inside 240V single phase customer house/building

1.May explain how the earth fault current flow route
2.If got local earthing was connected from ground to 11kV 3phase DEAD line, is it the fault current possible flow in to the customer earth point and flow out from local earth ground point & subsequently flow into 11kV 3 phase line

Regards

Shamsul
Malaysia

 

[Megawatt]

Hi... I am Shamsul from Malaysia

I have a question regarding to earth fault current if occur inside 240V single phase customer house/building

1.May explain how the earth fault current flow route
2.If got local earthing was connected from ground to 11kV 3phase DEAD line, is it the fault current possible flow in to the customer earth point and flow out from local earth ground point & subsequently flow into 11kV 3 phase line

Regards

Shamsul
Malaysia

Shamsul welcome to the forum and I wouldn’t think that would be possible but if you are wanting to protect youR home just add a SPD or (surge protection device) On your panel

 

[pc1966]

At the substation where you transform from 11kV to 240V there may be separate HV and LV earths (recent UK practice at least), or in some cases they are shared (used to be the UK case if earth rod/mat impedance was below 1 ohm, common practice in USA I think).

In both cases a HV fault can cause abnormal earth currents to flow in to the LV network, but lower values in the case of separate HV & LV earths of course.

While the reverse is possible (LV fault causing earth current back in to the HV network) the HV network won't really care as it is such a small percentage of the normal operating levels.

As Megawatt has said, you can fit surge protection devices to the main distribution board / panel in the LV system and that is becoming common practice in the UK (from 18th edition wiring regulations) and the USA. Typically though these are intended for lightning related spikes on the supply, not from HV/LV faults

I do not know if that is the case in Malaysia though, but given your very high lightning intensity I would expect so. More information from the UK can be seen here:

https://www.beama.org.uk/asset/186E3B6E%2DCFEB%2D4C75%2DB599624295252303/

https://www.erico.com/catalog/literature/E907W-WWEN.pdf