Zs to high

[brucelee]

hi to all,
a question for 2391 if zs to high three things you can do which should i put down if asked in written exam
1. shorten length of cable
2. increase csa of cable
3. change type of Circuit Breaker
4. in real world provide a rcd or change cb for rcbo

 

[Spa Key]

hi to all,
a question for 2391 if zs to high three things you can do which should i put down if asked in written exam
1. shorten length of cable
2. increase csa of cable
3. change type of Circuit Breaker
4. in real world provide a rcd or change cb for rcbo

You can't shorten the length of the cable. Well, you can, but then whatever was meant to be there in the first place is 10m closer to the DB.

You could also run another earthing conductor.

 

[Guest123]

2,3 & 4 are the answers the examiner will be looking for, although 4 would be worded more like.....provide additional protection by means of a residual current device.

 

[brucelee]

2,3 & 4 are the answers the examiner will be looking for, although 4 would be worded more like.....provide additional protection by means of a residual current device.

cheers lenny got my test on thursday
tutor told us first three and rcd in real world
thanks mate just going through a few questions that have been confusing me

can you tell me
1.
state why regular accuracy, in addition to calibration should be carried out on a inspector and testers instruments
2. two possible consequences if these accuracy checks are not carried out

 

[Risteard]

Supplementary bonding is another way.

 

[lee1002]

you could supply a supplementary cpc, also feed thr circuit through an rcd this could reduce the zs reading.

 

[ian.settle1]

hi to all,
a question for 2391 if zs to high three things you can do which should i put down if asked in written exam
1. shorten length of cable
2. increase csa of cable
3. change type of Circuit Breaker
4. in real world provide a rcd or change cb for rcbo

If the above 4 answers are what you are given I would use answer 2 as by increasing the CSA of the cable you would reduce the value of R1 thus reducing Zs, then change the type of breaker from a D to a C or a C to a B thus doubling the maximum permitted value of Zs each time and finally use a RCD/RCBO.

Answer 1 may not be practical as the position of the peice of equipment being supplied may not be able to be moved closer to the DB

 

[pushrod]

hi to all,
a question for 2391 if zs to high three things you can do which should i put down if asked in written exam
1. shorten length of cable
2. increase csa of cable
3. change type of Circuit Breaker
4. in real world provide a rcd or change cb for rcbo

Just to expand on 3. the change is from a D to C, or C to a B if appropriate.

or
again if it is appropriate to downgrade the size of the MCB eg a 20A to a 16A

 

[Des 56]

I always dis liked these spot the answer competitions that examinations thrive on
Its like doing the football pools,now where shall I put that x



Once you start thinking deeply instead of parroting the answers they get you into all sorts of bother

Oh for exams that ask you what you know, not find these find the weakest link trials

Just my opinion of course

 

[brucelee]

Thanks to all who have been helping me with my many questions
yeah des i know what you mean I have been studying since feb using lots of books sample papers this site writing test procedures over and over
It would be alright if the tutors at college showed you exactly what to put when asked for testing procedures
exam success gives a few, but does not go into detail of what to include and what not when and where its like guessing the wining numbers on the lottery if only eh mate
some of questions i have come across are confusing its like they expect us to have a degree in english lit
heads gone cant even spell it haha
tutor gave us course notes that says one thing Gn3 says another for example couse notes say routine checks to be carried out by electrically skilled person
GN3 says it does not but by someoe who can safely use and identify defects in the installation
Ah well I suppose we will find out if all this study has been worth while
thanks again back to the study

 

[ian.settle1]

Thanks to all who have been helping me with my many questions
yeah des i know what you mean I have been studying since feb using lots of books sample papers this sight writing test procedures over and over
It would be alright if the tutors at college showed you exactly what to put when asked for testing procedures
exam success gives a few, but does not go into detail of what to include and what not when and where its like guessing the wining numbers on the lottery if only eh mate
some of questions i have come across are confusing its like they expect us to have a degree in english lit
heads gone cant even spell it haha
tutor gave us course notes that says one thing Gn3 says another for example couse notes say routine checks to be carried out by electrically skilled person
GN3 says it does not but by someoe who can safely use and identify defects in the installation
Ah well I suppose we will find out if all this study has been worth while
thanks again back to the study

While it does not say skilled person in GN3 I would read it as the same

 

[brucelee]

While it does not say skilled person in GN3 I would read it as the same

yeah mate this was my point with tutor and after he finaly had a look he realized it was wrong and i am going with the Gn3 version

It was the same when i asked him about further investigation on selv first he said 5Mohm which is 16th figure then he said 2Mohm then he said no figure specified so they wont ask question but after speaking to people on here getting different answers
I am going with 2Mohm as this is the only figure i can find in 17th edition GN3

there are others like purpose of initial verification and purpose of periodic inspection

also whats the inspection and test required for a existing installation

so i just hope i get them right

 

[Risteard]

It was the same when i asked him about further investigation on selv first he said 5Mohm which is 16th figure then he said 2Mohm then he said no figure specified so they wont ask question but after speaking to people on here getting different answers
I am going with 2Mohm as this is the only figure i can find in 17th edition GN3

Below 1 (one) Megohm requires further investigation.

 

[Risteard]

also whats the inspection and test required for a existing installation

You wrote the answer in the line above that!

 

[brucelee]

Below 1 (one) Megohm requires further investigation.

hi risteard you told me that before and said it was out of regs is that not for surge protective devices that and for testing between selv and band II
on page 158 of regs it doesnt say that
and when you say i wrote the answer for inspecting and test on a existing
do you mean periodic inspection
and not periodic inspection and test as it says in gn3