Electronics > Beginners
Single Pole or 1P + N circuit breakers
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Zero999:

--- Quote from: Monkeh on March 26, 2019, 11:11:34 pm ---
--- Quote from: Zero999 on March 26, 2019, 10:59:53 pm ---
--- Quote from: Monkeh on March 26, 2019, 09:38:27 pm ---
--- Quote from: Zero999 on March 26, 2019, 01:58:26 pm ---Disconnecting the neutral is safer, because it might be live, if it's broken somewhere upstream of the breaker.

--- End quote ---

This is irrelevant for the purpose of a circuit breaker. It is not isolation, nor is it functional switching - it is overcurrent protection.

--- End quote ---
No it's not irrelevant. It still has to make the circuit safe, i.e. dead, which won't happen with a single pole device, if there's a break in the neutral conductor.

--- End quote ---

It has to end the condition of overcurrent. Again, it is an overcurrent protective device, not an isolator.

--- End quote ---
It still has to make the circuit safe, i.e. isolate it. Over-current can cause electric shock, as the voltage on exposed metal parts can reach dangerous levels. Whether or not the circuit breaker is supposed to be used for isolation or not. It must safely disconnect the circuit from the supply.
soldar:
In Spain regulations require the circuit breaker to break both conductors and I understand there are several good reasons to do so but in my apartment I have a very simple panel which only cuts the phase side and not the neutral wire.

Regulations here also require a GFCI which protects all circuits and cuts both wires but I have it protecting only kitchen and bathroom but not the other rooms.
Monkeh:

--- Quote from: Zero999 on March 27, 2019, 01:25:57 pm ---It still has to make the circuit safe, i.e. isolate it.
--- End quote ---

No, it has to clear the fault. Isolation is not the same thing.
Benta:

--- Quote from: Monkeh on March 27, 2019, 07:49:59 pm ---
--- Quote from: Zero999 on March 27, 2019, 01:25:57 pm ---It still has to make the circuit safe, i.e. isolate it.
--- End quote ---

No, it has to clear the fault. Isolation is not the same thing.

--- End quote ---

Agreed.
Let's go back some years: circuit breakers were thermofuses/filaments that melted. They were only placed in the live conductor in the fuse panel.
The resettable breakers have the same function, which is to open the circuit in case of overload.
Fusing neutral is nonsense.
soldar:

--- Quote from: Benta on March 27, 2019, 08:34:28 pm --- Fusing neutral is nonsense.
--- End quote ---

In Spain it is required by the regulations and there are several good reasons. One is that some places are supplied 230 V with two phases from a 127/230 volt system and there you, obviously, need to cut both wires just like in America you need to cut both wires in a 220 V circuit.

And there are other reasons.

Also, there are different ways of implementing and connecting protective earth and a lot of people think there is only one correct way to do it and any other way is wrong.

Again, in my apartment I have single circuit breakers on the phase side but there are good reasons to cut both wires after an overload or GFCI.

In Spain, like most of central Europe, we use Schucko plugs which are an abomination to everything that is decent and holy. Non-polarized, requires great force to pull, earth tabs can bend out or shape or make bad contact, too big.
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