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Mains sockets with no earth
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Someone:

--- Quote from: michael@metgen.tech on January 19, 2021, 02:26:50 am ---So, it sounds to me as though I should install some three-pin sockets (US style), on extension cords, with the earth connectors disconnected from each other - that would produce the same effect as cutting off the three-pin plugs and putting on two-pin plugs. Then I need to stop worrying about the absence of an earth connector?
--- End quote ---
No, equipment that has a mains earth pin usually relies on it for safety and/or EMC. Removing that connection is a very very bad idea.

If you don't understand the standards/requirements (which is plainly obvious from your posts so far) then suck it up and hire a professional to do the job. Just ask an electrician to put modern grounded points everywhere and its done.
jmelson:

--- Quote from: michael@metgen.tech on January 19, 2021, 02:26:50 am ---On the RCD front, I always thought that they were to guard against earth faults... so I don't understand how they can work without a reference to earth.

--- End quote ---
They compare current on line and neutral.  If the current is the same, the devices must be OK, all current flows out one outlet prong and back on the other.  If the currents DO NOT match, then the current MUST be flowing out of the device somewhere, and typically that would be through a person's body.
The comparison is done by passing both L and N wires through a ferrite core.  Only equal and opposite currents cancel out.

Japan generally has no ground pin on any residential sockets, but they do in industrial and lab settings.

Jon
michael@metgen.tech:

--- Quote from: Someone on January 19, 2021, 09:47:57 pm ---
--- Quote from: michael@metgen.tech on January 19, 2021, 02:26:50 am ---So, it sounds to me as though I should install some three-pin sockets (US style), on extension cords, with the earth connectors disconnected from each other - that would produce the same effect as cutting off the three-pin plugs and putting on two-pin plugs. Then I need to stop worrying about the absence of an earth connector?
--- End quote ---
No, equipment that has a mains earth pin usually relies on it for safety and/or EMC. Removing that connection is a very very bad idea.

If you don't understand the standards/requirements (which is plainly obvious from your posts so far) then suck it up and hire a professional to do the job. Just ask an electrician to put modern grounded points everywhere and its done.

--- End quote ---

Your comment doesn't really make sense - obviously not coming at this from a Japan perspective.

The standard in Japan is to NOT have any earthing. There are no "modern grounded points". The problem I have is that I have equipment that is not Japanese, has earth connectors and, for some, an uninsulated metal case. So "hiring a professional" won't change anything. I am trying to better understand of the risks that I am actually exposed to by following the local standards and if there are any workable mitigations.


Mike
michael@metgen.tech:

--- Quote from: jmelson on January 19, 2021, 11:47:22 pm ---
--- Quote from: michael@metgen.tech on January 19, 2021, 02:26:50 am ---On the RCD front, I always thought that they were to guard against earth faults... so I don't understand how they can work without a reference to earth.

--- End quote ---
They compare current on line and neutral.  If the current is the same, the devices must be OK, all current flows out one outlet prong and back on the other.  If the currents DO NOT match, then the current MUST be flowing out of the device somewhere, and typically that would be through a person's body.
The comparison is done by passing both L and N wires through a ferrite core.  Only equal and opposite currents cancel out.

--- End quote ---

Thanks. Obvious now that I look at the insides of one.


--- Quote from: jmelson on January 19, 2021, 11:47:22 pm ---Japan generally has no ground pin on any residential sockets, but they do in industrial and lab settings.

--- End quote ---

My experience too.

Thanks,

Mike
Zero999:
It's true that RCDs will work, if the appliance lacks an earth connection, but an earth is required at the supply side. RCDs need the mains supply to be earth referenced, so they won't work if the entire circuit lacks an earth connection. Try connecting an RCD to the secondary of an isolation transformer and note that it won't trip, if either conductor is connected to earth.
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