Neutral to Earth

[Mark Wright]

What I don't understand is if you have a circuit in series the voltage will be different and in parallel the the current will be different at the end also obviously the load will use some so how can what's going out on the live be monitored coming back on the Neutral it won't be the same?
[automerge]1594906338[/automerge]
@op JW has a video call RCD neutral earth fault not watched it yet.
but..... there is another video by bigclivedotcom iirc he takes an RCD apart and inside is a Resistor used for the test button when you press the test button its not just mechanical the Resistor actually lets a current flow to trip the RCD - he can actually see the value of the resistor -check that video out.

 

[DPG]

What I don't understand is if you have a circuit in series the voltage will be different and in parallel the the current will be different at the end also obviously the load will use some so how can what's going out on the live be monitored coming back on the Neutral it won't be the same?
[automerge]1594906338[/automerge]
@op JW has a video call RCD neutral earth fault not watched it yet.
but..... there is another video by bigclivedotcom iirc he takes an RCD apart and inside is a Resistor used for the test button when you press the test button its not just mechanical the Resistor actually lets a current flow to trip the RCD - he can actually see the value of the resistor -check that video out.

I think the RCD test functionality is fairly well known. But always worth a reminder.

 

[Lucien Nunes]

how can what's going out on the live be monitored coming back on the Neutral it won't be the same

Current can't just disappear. If it goes down the line conductor every bit of it ought to go through the load(s) and come back up the neutral. Any that doesn't has escaped the circuit, probably to earth, which is exactly the leakage that the RCD is looking for.

 

[ForkEnigma]

p.s. I am enjoying the technical chat, whilst having a beer. certainly beats posts about peoples lights not working after they have (male chicken'd) about with them.

Yeah good fun isn't it. Trust me there will be a lot more! I too was having a beer when I started this thread.

 

[davesparks]

Where the maximum Zs value for a protective device cannot be satisfied in a TN system, Regulation 531.3. 1 permits an RCD (including an RCBO) to be used to provide automatic disconnection of the supply. Table 41.5 would therefore apply and the maximum tablulated Zs value for a 30mA RCD is 1667 ohms

I don't have a regs book to hand but that sounds like the pre-18th requirements

 

[ForkEnigma]

I don't have a regs book to hand but that sounds like the pre-18th requirements

The physics have not changed, and the values are the same in the 18th