General > General Technical Chat
Mains sockets with no earth
bdunham7:
--- Quote from: themadhippy on January 18, 2021, 12:59:59 pm ---if you dont have an earth your rcd will not work.were does the fault current go as there is no path for it to travel.
--- End quote ---
GFI does not depend on having an earth connection, nor does it care what the path is for current to travel outside of the two wires it monitors. If a current is flowing through you, then that amount of current will be missing from the return current in the neutral. GFI sees the imbalance and trips.
Red Squirrel:
You could try to ground to the water line but these days with pex that can be hit and miss as the line might turn to pex at some point before it goes into the actual ground. Worse case scenario run stuff off a GFCI, it will at least protect you from ground faults. I've tested this and it does work. For Christmas light stuff I often need to convert from 2 prong to 3 prong because stuff like timers only have 2 prong and the extension cord, power bars etc are 3, so I just made a converter box that has a GFCI.
bdunham7:
--- Quote from: michael@metgen.tech on January 18, 2021, 06:19:48 am ---
* Without an earth connection I don't have RCD protection - is that right?
--- End quote ---
GFI/RCD does not depend on there being a ground wire, although if the circuit is totally isolated (not ground referenced) the behavior may be unpredictable in fault situations. You would want to know what your RCD trip level is. US-style GFIs trip at 5mA or so, which gives good protection against electric shocks. You could add a GFI socket to your workbench outlet if you wanted the extra protection--if they are available there.
themadhippy:
--- Quote ---I don't know how is the PE and N overthere, but at my place they certainly very close to eachother Ohmic wise
--- End quote ---
The neutral -earth link is done on the suppliers side in the uk,well apart from the rare TNC arrangement, so disconnecting the consumer side main earth there is no path to earth via neutral,in fact when carrying out a test of an electrical installation one of the tests is to confirm the resistance between earth and neutral is greater than 1 Meg ohm
--- Quote ---without any strapping. I wouldn't advise to anyone to try that...
--- End quote ---
If your of a nervous disposition use a resistor, a value upto 1666.6667 ohms should work on a 30ma trip in the uk between neutral and earth
--- Quote ---GFI does not depend on having an earth connection, nor does it care what the path is for current to travel outside of the two wires it monitors.
--- End quote ---
whilst the rcd dosnt have an earth connection it still relies on the circuit somewhere being connected to earth,otherwise theirs nowhere for the imbalance current to flow.If the experiment mentioned above is to scary try putting an rcd on the secondary of an isolating transformer and connect the output to earth ,what happens?
bdunham7:
--- Quote from: themadhippy on January 18, 2021, 04:33:23 pm ---whilst the rcd dosnt have an earth connection it still relies on the circuit somewhere being connected to earth,otherwise theirs nowhere for the imbalance current to flow.If the experiment mentioned above is to scary try putting an rcd on the secondary of an isolating transformer and connect the output to earth ,what happens?
--- End quote ---
True, in a truly isolated system the RCD won't trip because there is no fault current. But since there's no fault current, there's no shock and nothing to protect from.
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