An Awful Feeling This

[IQ Electrical]

the loop length for circuit 1 is 50 m long the ze is is 0.11 ohms

determine showing all calculations the r1 + r2 and the expected zs

7.41 x 50/1000 = 0.37 12.10 x 50/1000 = 0.60

zs = ze = (r1 = r2)

0.11 + (0.37 + 0.60) = 1.08

have i done this correctly?

I can't confirm the mOhm values but the maths is correct.

You MUST use (R1+R2) when doing these calculations and remember that r1, rn and r2 are reserved for ring continuity figures, this exam is very big on correct terminology.

 

[IQ Electrical]

Hang on, is this a ring final circuit?

 

[gap30]

Hang on, is this a ring final circuit?

yes i just shortened the question the m/ohm/ for 2.5 is 7.41 and 1.5 is 12.10

i am not great at the terminology but i am getting there with the calculations

in some crazy way i am actually finding the long questions easier than the short ones atm

 

[IQ Electrical]

If it's a ring then the R1+R2 value is r1+r2/4

R1+R2=0.37+0.60/4

R1+R2=0.24 Ohms

Zs=(R1+R2)+Ze

Zs=0.35 Ohms

 

[gap30]

Have a look at the question as it tells you the voltage is 400v three phase.

So its 8% of the 400v if the low voltage installation is supplied from a private low voltage supply.

Hope this helps.

just ordered a set of regs from fleabay so they should be with me in the next couple of days - the only problem i found with the regs in the past was navigating them, i always favoured the on site guide for obvious reasons

 

[gap30]

If it's a ring then the R1+R2 value is r1+r2/4

R1+R2=0.37+0.60/4

R1+R2=0.24 Ohms

Zs=(R1+R2)+Ze

Zs=0.35 Ohms

no thats for your cross connections isnt it are you not thinking of step 2 of ring final circuit continuity? now i am really confused

your end to end resistances are your r1 and r2 values

 

[IQ Electrical]

If you are asked to calculate R1+R2 on a ring final circuit and you are given the 'loop length' then you need to divide the end to end continuity readings for r1 and r2 by 4 to arrive at a figure for R1+R2.

It's actually mentioned in step 3 of the continuity of ring final conductors test (if you were measuring R1+R2 then you would not need to divide by 4).

 

[gap30]

If you are asked to calculate R1+R2 on a ring final circuit and you are given the 'loop length' then you need to divide the end to end continuity readings for r1 and r2 by 4 to arrive at a figure for R1+R2.

what a d**k! of course, i keep getting caught on the little things so basically there was about 10 marks down the drain

LOOP LENGTH

(0.37+0.60)/4 = 0.24 + 0.11 = 0.35

 

[IQ Electrical]

what a d**k! of course, i keep getting caught on the little things so basically there was about 10 marks down the drain

LOOP LENGTH

Scan the question twice, find out EXACTLY what you've been given and EXACTLY what they're asking.

 

[gap30]

Scan the question twice, find out EXACTLY what you've been given and EXACTLY what they're asking.

these questions are all simple in theory, but a nightmare in principal lol

 

[IQ Electrical]

these questions are all simple in theory, but a nightmare in principal lol

It'll just click once you know the formats and double check the questions.

Also remember that on longer testing questions, if you fail to mention say deducting test lead resistances before a continuity test, even though you may go on to describe the rest of the process perfectly, your end result would be incorrect so answers are heavily penalised in that scenario.

 

[brucelee]

yes mate practice writing test procedures over and over then you will have it nailed

Iq is spot on as usual

you miss a important part of test procedure and will get no further marks for that question

and when doing r1,r2,rn the r2 will always be slghtly higher for T/E as the cpc is smaller so resistance will be higher approx 2.5/1.5mm = 1.67 times higher
so you R1 +R2 will be slightly higher than the R1 + RN value

and like he says read the question a couple of times until your sure you know what they are asking before answering

 

[gap30]

i have looked at that many questions in the last four days my head is fryed but thats the advice i was given - read gn3, then read it again, then read it again, and keep going over previous exam papers, i have just ordered on site guide as well

 

[brucelee]

also have a look at GS38 which is for test instruments eg finger guards 4mm probe tips preferably 2mm
also memorandum of guidance on elecy at work regs i have it in pdf if you want it as some of these come up
when you get the regs read part 6 and especially 7 zones for fountains bathrooms etc
100mA rcds sockets outlets in agricultural
300mA rcds protection aginst fire in agricultural
500mA rcds sockets on construction sites
a few questions come up out of part 7 special locations
locations containing baths or showers
rooms containing sauna heaters
swimming pools and other basins

learn IP ratings
protection against water
Ipx8 protection against continous submersion
ipx7 protection against temporary submersion eg min for zone 0 bath
ipx6 protection against powerful water jets
ipx5 protection against water jets
ipx4 protection against splashing water
ip3x protection against spraying water
ip2x protection against dripping water when tilted up to 15degrees
ipx1 protection against dfriping water

protection against objects

ip6x dust tight
ip5x dust protected
ip4x protection againstsolid objects greater than 1mm and protection against 1mm wires for horizontal top surface eg CCU tops of sockets, enclosures etc solidobjects
IPXXD is same but only protection against 1mm wires
ip3x against solidobjects greater than 2.5mm
ip2x protection against solid objects greater than 12mm eg your finger or a standard test fingr and small rocks stones etc
ip1x protection against 50mm solid objects eg hand

IpxxA protection against large part of body
ipxxb protection against contact by standard test finger only
ipxxc protection against tool eg screwdriver
ipxxd protection against contactby 1mm wire

 

[gap30]

tell you where i am struggling conductor and insulation resistance

what happens to conductor resistance if a cable length is increased etc etc

i keep getting them wrong time after time

oh and the schedules of circuit details the one you stick in the door on the db

list 5 items - ermmmmm?