just started the 2391

[i=p/u]

this thread will go on for quite a while (14 WEEKS), to exams... ive nearly read gn3 for the first time and there is a few things i dont fully understand but im sure i will for when the time comes from help from you guys/dudes/punks who know just a little to much.

 

[i=p/u]

trying to get me head round this has turned me into a loonatic , whiskey went out the twindow in 2009, so help yourself

 

[i=p/u]

anyone out there and nothing todo, wanna drink coffee too half past two and discuss a few electricalbitz

what about this one..an example of a C3 observation is earth leakage circuit breaker installed at origin of tt installation???? why is this as there is 1000s out there

 

[nick182]

ill help u study if u want?

ill just throw u a couple of 2391 questions if tht helps?

 

[i=p/u]

roooooooooooo like a dog

 

[nick182]

alright lets do this..

The maximum tabulated values of earth loop impedance, given in BS7671, for three circuits are 2.3Ohms, 1.44Ohms and 0.57Ohms.
The measured values for these circuits are 1.22Ohms, 0.44Ohms and 0.36Ohms respectively. Determine if the measured values are acceptable.
Show all calculations.

 

[nick182]

Hint: appendix 14 of bs7671

 

[nick182]

An RCD to BS EN 61008 is to provide additional protection for a 13a socket-outlets, for use by an ordinary persons, intended for general use. State
a)the maximum permitted operating current (I∆n) of the RCD
b)the maximum test current when testing a device in a)
c)the maximum permitted disconnection time for test in b).

 

[i=p/u]

2.3 ohms x 0.8= 1.84 0hms ,1.22 is acceptable
1.44ohms x0.8= 1.15 ohms, 0.44 ohms is acceptable
0.57 ohms x 0.8=0.45 ohms,0.36 ohms is acceptable

alright lets do this..

The maximum tabulated values of earth loop impedance, given in BS7671, for three circuits are 2.3Ohms, 1.44Ohms and 0.57Ohms.
The measured values for these circuits are 1.22Ohms, 0.44Ohms and 0.36Ohms respectively. Determine if the measured values are acceptable.
Show all calculations.

 

[i=p/u]

a, 30mA
b,150mA
c,40ms

An RCD to BS EN 61008 is to provide additional protection for a 13a socket-outlets, for use by an ordinary persons, intended for general use. State
a)the maximum permitted operating current (I∆n) of the RCD
b)the maximum test current when testing a device in a)
c)the maximum permitted disconnection time for test in b).

 

[nick182]

right ok.. last one for an hour coz the mrs is makin me sit thru the only way is essex... :90: god i hate that show.

The perspective fault current at the origin of a 230v single phase installation forming part of a TN-S system is to be measured. State
a) the conductors between which testing is to be carried out
b) which result from a) is to be recorded on an Electrical Installation Condition Report

 

[nick182]

well done.. total of 6 marks.. bbs

 

[i=p/u]

in a bathroom does your raidator have have to be connected to the lighting circuit in bathroom??? or is that old practices..

i thought if you have main protective bonding in place , it eradicates all this supplemntry bonding /equopential bonding

 

[i=p/u]

name the protective conductive that connects the following;

exposed conductive parts to extraneous conductive parts where a circuit discconnecion times cannot be met

awnser; supplementry bonding conductor


is that right something telling me equapotential bondonding conductors or is that the same as supplementry

 

[GLENNSPARK]

in a bathroom does your raidator have have to be connected to the lighting circuit in bathroom??? or is that old practices..

i thought if you have main protective bonding in place , it eradicates all this supplemntry bonding /equopential bonding

older installations that dont have RCD protection will/should have supplementary bonding between exposed and extrainious parts.......the use of RCDs does away with this arangement....but if working on an older install where theres no additional protection by means of RCD...and supplementary bonding isn`t in place.....then both the circuit feeding the bathroom (special location) and the absence of supplementary bonding within special location becomes a "2"......

 

[i=p/u]

you wouldnt have that diagram on earthing and protective conductors from the red wiring regs on your computer or where i can find it.. dont have red book anymore or what the parts in question are

they labelled M, C, P