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Mains sockets with no earth

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Brumby:

--- Quote from: vk6zgo on January 19, 2021, 07:26:27 am ---Yes, another name for such devices is "core balance relay".

--- End quote ---

Now you're showing your age.....  ;)

tooki:

--- Quote from: themadhippy on January 19, 2021, 01:14:31 am ---
--- Quote ---Sure it will
--- End quote ---
so if we don't need an earth why don't we use an rcd on the secondary of an isolating transformer?after all thats  a circuit without an earth

--- Quote ---Neutral is tied to earth somewhere in the domestic wiring system of every developed nation as far as I'm aware
--- End quote ---
not on the consumers side,otherwise your rcd/gfi would be permanently tripped

--- End quote ---
Uhhhh… what? No. The RCD isn't looking at what's happening upstream of it (i.e. in the power grid). It simply has inputs and outputs for the L and N, and if the current that flows in isn't the same as what flows out, it trips. If N and PE are tied together at the consumer unit, that's still upstream of the RCD, and thus irrelevant to it.

In fact, RCDs are used when it's impractical to add an actual protective earth conductor, precisely because they do add protection when earth is missing.

themadhippy:
the post that started it all

--- Quote ---You still have RCD protection without an earth.
--- End quote ---
without  earth  there is no return path so  would the experts like to explain how a current can flow in what is effectively an open circuit

--- Quote ---If N and PE are tied together at the consumer unit
--- End quote ---
i meant the consumers side,or output, of the rcd

--- Quote ---precisely because they do add protection when earth is missing
--- End quote ---
again i ask,if earth is missing how does a fault current flow?


bdunham7:

--- Quote from: themadhippy on January 19, 2021, 12:24:33 pm --- without  earth  there is no return path so  would the experts like to explain how a current can flow in what is effectively an open circuit

--- End quote ---

If there truly is no ground reference for both the voltage and your feet, indeed no current will flow and the RCD will not trip.  But it doesn't need to--because there's no fault current to worry about.  The RCD is still standing by for any faults that develop that result in current flowing through you other than those that result from you touching both sides of the power.

Monkeh:

--- Quote from: themadhippy on January 19, 2021, 12:24:33 pm ---the post that started it all

--- Quote ---You still have RCD protection without an earth.
--- End quote ---
without  earth  there is no return path so  would the experts like to explain how a current can flow in what is effectively an open circuit

--- Quote ---If N and PE are tied together at the consumer unit
--- End quote ---
i meant the consumers side,or output, of the rcd

--- Quote ---precisely because they do add protection when earth is missing
--- End quote ---
again i ask,if earth is missing how does a fault current flow?

--- End quote ---

Are we accidentally equating earth with the CPC?

The neutral, sort of by definition of being neutral, is connected to earth (the 'greater mass of earth', the soil under your feet). You do not need an earth wire in an installation for current to flow via the literal earth.

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