TT system undetectable?

[wisengruber]

Was looking into earthing methods, I came across a potential issue. What if a TT system's earth accidentally contacts the PEN conductor enough to create a parallel path, but not fully sever it? Wont this be basically undetectable? The RCD and overcurrent protection wouldnt trip, and the whole installation could stay energized, waiting for a lower resistance path like a person. Could it even re-energize after a discharge? And lastly, would the DNO have any way to detect this? It seems like even the meter wouldn't show anything unusual. Check image for reference.

 

[feyvahfatale]

Oh! that accidental TT earth PEN contact is a real head-scratcher and kinda scary to think about. I think it's right that the standard protection might miss a partial connection. Sounds like something the DNO would have a tough time spotting too. Definitely it's best to keep those systems totally separate.

 

[wisengruber]

Head scratcher is right lol, if a TT system's earth accidentally contacts the PEN conductor and then create a parallel path without a full fault, it sure can be a very dangerous and hard to detect heck of a situation.

 

[ShockSurge]

Absolutely, I totally agree, that's one of those tricky situations that can really fly under the radar.

I encountered something similar a few years back during a farm installation. A corroded connector allowed a PEN to touch an old earth rod, which ended up creating a parallel path that we didn't initially notice. There wasn't an obvious fault, but we noticed some strange voltage fluctuations on various circuits. It took us a day and a half to figure it out.