Revision Help

[R.Beck]

Hi, Im currently studying for C&G 2330 Level 3 - Installation. Currently Revising and will be getting stuck on some questions and would like help, so if people could answer them and help me when im stuck i woukll greatly appreciate it.
Here are some questions im stuck on.(Ill add more to this post more than likely)

1. A Low Resistance Ohm Meter is belived to be giving incorrect readings. State:-
- A) Two Methods which could be used to verify the accuracy of the instrument
- B)The Action To Be taken if the meter is found to be incorrect.

2.Each of the following protective devices , typical installation or load type, Were would the be used?
-A) Type Bcircuit breaker to BS EN 60898
B) BS 88 gG Cartridge Fuse
C) BS 1361 type II
D) Type C Circuit breaker to BS EN 60898
E) Bs 88gM Cartridge Fuse
F) RCD to BS EN 61009

 

[R.Beck]

Can Noone Help?

 

[m4tty]

Hi, Im currently studying for C&G 2330 Level 3 - Installation. Currently Revising and will be getting stuck on some questions and would like help, so if people could answer them and help me when im stuck i woukll greatly appreciate it.
Here are some questions im stuck on.(Ill add more to this post more than likely)

1. A Low Resistance Ohm Meter is belived to be giving incorrect readings. State:-
- A) Two Methods which could be used to verify the accuracy of the instrument
- B)The Action To Be taken if the meter is found to be incorrect.

2.Each of the following protective devices , typical installation or load type, Were would the be used?
-A) Type Bcircuit breaker to BS EN 60898
B) BS 88 gG Cartridge Fuse
C) BS 1361 type II
D) Type C Circuit breaker to BS EN 60898
E) Bs 88gM Cartridge Fuse
F) RCD to BS EN 61009

1) a) Test it on a known source / check box /
b) Have it calibrated

2) a) Domestic
d) Office /Industrial Banks of Flourescent Lighting (Inductive)
f) Domestic Cct RCBO

Not much help but its a start and others will probably add / correct me

 

[kablue2000]

Hi, Im currently studying for C&G 2330 Level 3 - Installation. Currently Revising and will be getting stuck on some questions and would like help, so if people could answer them and help me when im stuck i woukll greatly appreciate it.
Here are some questions im stuck on.(Ill add more to this post more than likely)

1. A Low Resistance Ohm Meter is belived to be giving incorrect readings. State:-
- A) Two Methods which could be used to verify the accuracy of the instrument
- B)The Action To Be taken if the meter is found to be incorrect.

2.Each of the following protective devices , typical installation or load type, Were would the be used?
-A) Type Bcircuit breaker to BS EN 60898
B) BS 88 gG Cartridge Fuse
C) BS 1361 type II
D) Type C Circuit breaker to BS EN 60898
E) Bs 88gM Cartridge Fuse
F) RCD to BS EN 61009

2a domestic ring final circuit/radial circuit/lighting circuit

2d and e motor circuits
2b high pfc

 

[R.Beck]

Thank you For the help ! If anyone can help me out with the rest still. Only 2C I need answering.!
Much Appreciated !

 

[acat]

Not 100% but Im pretty sure thats the main fuse at the installation.


Chris

 

[m4tty]

^^^ what acat says is correct

 

[R.Beck]

Brilliant. Thanks alot

I have 2 more questions now also haha ^^

1) Lets say we have a 6 may consumer unit with 5 circuits connected and the 6th left as a spare. we then carry out an insulation resistance test and get results.
i.e circuit: 1-10M Ohm, 2-20M Ohm,3-30M Ohm, 4-40 M Ohm,5-50 M Ohm,6-0M Ohm(spare).

To calculate the overall value of the insulation resistance if all circuits were tested would i just Add them and divide by 6? (10+20+30+40+50+0)/6 = Overall Insulation Resistance.

2) Identify 3 possible faults while carrying out a visual inspection prior to commissioning an installation on
a) a pendant type luminaire with 3 plate wiring.
b) a consumer unit (distribution board)

Im presuming for 2B that would include wireing in wrong order(forgot what the fault is called) were you put MCBs out of order(largest closest to main switch) - Can someone just tell me if that would be one.

Thankyou ^_^

 

[acat]

I would have thought mcbs in the wrong order would be bad practice only these days with split boards,
NICEIC wired our house up couple of years ago and largest is other side of the board and sizes work down towards main switch, if that is true does anyone know the reg for it.


Visual faults could be

Wrong size earth cable
Loose connections
Wrong mcb used ie 32amp on lighting circuit
Return part of ring circuit not connected



Chris

 

[m4tty]

I would have thought mcbs in the wrong order would be bad practice only these days with split boards,
NICEIC wired our house up couple of years ago and largest is other side of the board and sizes work down towards main switch, if that is true does anyone know the reg for it.

Dont think its a reg just best practice

 

[acat]

Thanks you have saved me looking through the BRB for something that does not exist



Chris

 

[m4tty]

1) Lets say we have a 6 may consumer unit with 5 circuits connected and the 6th left as a spare. we then carry out an insulation resistance test and get results.
i.e circuit: 1-10M Ohm, 2-20M Ohm,3-30M Ohm, 4-40 M Ohm,5-50 M Ohm,6-0M Ohm(spare).

To calculate the overall value of the insulation resistance if all circuits were tested would i just Add them and divide by 6? (10+20+30+40+50+0)/6 = Overall Insulation Resistance.


No mate to work out resistors in parallel you have to do following

1/10 + 1/20 + 1/30 + 1/40 + 1/50 =

0.1 + 0.05 + 0.033 + 0.025 + 0.02 = 0.228

1/0.228 = 4.39 MegOhms

Correct me if im wrong anybody cheers

 

[old dog]

the question could be worded wrong . i came across a question to find the unknown R

1/Requv = 1/R1 + 1/R2 + 1/R3 + 1/R4 + 1/Runknown
therefore
Runknown = 1/1Requiv - 1/R1 - 1/R2 - 1/R3 - 1/R4

 

[R.Beck]

Yeah it may just be best practise, ill look it up tomorrow like Thanks alot for help people

And oh yeah it is just resistant isn't it, abit silly by me there. you people are gods at this i'll give everyone thanks tomorrow by then i would probably have more questions!

 

[Banjo]

1) Lets say we have a 6 may consumer unit with 5 circuits connected and the 6th left as a spare. we then carry out an insulation resistance test and get results.
i.e circuit: 1-10M Ohm, 2-20M Ohm,3-30M Ohm, 4-40 M Ohm,5-50 M Ohm,6-0M Ohm(spare).

To calculate the overall value of the insulation resistance if all circuits were tested would i just Add them and divide by 6? (10+20+30+40+50+0)/6 = Overall Insulation Resistance.


No mate to work out resistors in parallel you have to do following

1/10 + 1/20 + 1/30 + 1/40 + 1/50 =

0.1 + 0.05 + 0.033 + 0.025 + 0.02 = 0.228

1/0.228 = 4.39 MegOhms

Correct me if im wrong anybody cheers

You are correct mate.

1/10 + 1/20 + 1/30 + 1/40 + 1/50

10 x 20 x 30 x 40 x 50 = 12000000

10/12000000 = 1200000
20/12000000 = 600000
30/12000000 = 400000
40/12000000 = 300000
50/12000000 = 240000

1200000 + 600000 + 400000 + 300000 + 240000 / 12000000 (then swap it over)

12000000 / 1200000 + 600000 + 400000 + 300000 + 240000

= 4.38Mohms