Earth fault and open circuit

[daws124]

Could anyone explain a likely cause for each of those?

Is the cause of an open circuit and broken conductor? Help would be appreciated. Can't find any info on this :/

 

[Tridentsystems]

Could be

 

[Patto]

Can you give more info?

 

[trev]

Have a think about this Daws it's fairly basic stuff, I'm guessing this is all new to you though. An open circuit could be caused by a broken conductor, it could be caused by a switch not operating (deliberately trying to keep it simple)
What's your thoughts on what an earth fault is?

 

[Richard Burns]

As Trev says try and think about what is meant by an
Earth fault: once you know the description of an earth fault then it should be come clear how can occur.
Open Circuit: if this is the disconnection of a continuous circuit path from line to neutral then where and how can this occur, think of items you know about and where such a fault could happen.

 

[daws124]

Thanks for the help lads,got there in the end. I'm now struggling like he'll with the 2365 303/304/305 assignments!!! So close to quitting as I just don't know where to start with them!!

 

[trev]

Don't quit! post up what you're struggling with and have a go at the answers, you'll get the help you need

 

[daws124]

Thanks I appreciate that. Struggling with why we do the test sequence before putting a install back into service? I know the tests "cripplers" but don't know why we do it in that order?? Hmmm

 

[telectrix]

as a start, it's pointless doing an insulation ( megger ) test before ensuring that there is circuit continuity, else you would be testing only part of a circuit if there was a break somewhere. likewise, live tests must not be done before all dead tests confirm that the circuit is safe to be energised.

 

[daws124]

Thank you for that help,makes sense,quite obvious really when someone explains!! Hero!

 

[kingeri]

Bless ya, keep at it and you'll get there!

 

[daws124]

I'm trying mate! Appreciating the help!

 

[Silly Sausage]

Get your fundamental basics nailed first.
Ohm's Law, Kirchhoff's etc etc...burnt into your mind so you don't have to think about them.
Bit like walking into a pub, you never think about how to ask for a pint. Well I hope not!

 

[daws124]

Yeah very true! Never forget how to do that! Ha

So if I was to add another circuit to an installation the insulation resistance between the live conductors would decrease as there is more cable for the current to leak?? Am I thinking right? If so that would be the same for a longer length of cable?!

 

[telectrix]

nope. picture an extra circuit added is in parallel to the existing circuits. impedances in parallel decrease the overall impedance. longer cable would increase resistance.