An Awful Feeling This

[IQ Electrical]

An installation has been seriously overloaded and requires investigation. State
a) the type of inspection and test that would be required. (1 mark)
b) two areas which require close inspection as a result of the overloading. (2 marks)

could this be any 2 from the scope ie SADCOW

Safety,ageing, deterioration, corrosion, excessive overloading, wear and tear

The SADCOW just leads you back to the question really, the areas for close inspection would be areas that might have sustained damage from the associated overheating:

Distribution equipment and as Spin suggests, conductor insulation properties.

I could make a good case for close inspection of overcurrent protection too, how did that installation become 'seriously overloaded'?

 

[gap30]

The SADCOW just leads you back to the question really, the areas for close inspection would be areas that might have sustained damage from the associated overheating:

Distribution equipment and as Spin suggests, conductor insulation properties.

I could make a good case for close inspection of overcurrent protection too, how did that installation become 'seriously overloaded'?

Thats the first thing i thought but thats not the question they are asking is it? they want to know the after affects

Thanks spin,iq in the real world the first thing you are gonna do is go straight to the mains

atm i am trying to look at the questions and the wording more closely - damage to main switch, damage to main incoming cables, damage to cables feeding circuits even possible damage to fixed electrical equipment?

 

[IQ Electrical]

[/B]

Thats the first thing i thought but thats not the question they are asking is it? they want to know the after affects

Thanks spin,iq in the real world the first thing you are gonna do is go straight to the mains

atm i am trying to look at the questions and the wording more closely - damage to main switch, damage to main incoming cables, damage to cables feeding circuits even possible damage to fixed electrical equipment?

Stay away from 'fixed equipment'.

The question asks for '2 areas which require close inspection' 2 of the 3 above would get you marks but you won't find much mention of fixed equipment in GN3 and even if it was covered, the INSTALLATION being overloaded would probably have little effect on fixed equipment but more on distribution and wiring.

 

[gap30]

17 State the
a) purpose of the IP coding system
b) level of protection provided by
i) IPXXB - finger contact only
ii) IP4X. - solid or foreign bodies up to 1mm

is this to verify the level of ingress protection to fixed electrical equipment?

 

[JUD]

17 State the
a) purpose of the IP coding system
b) level of protection provided by
i) IPXXB - finger contact only
ii) IP4X. - solid or foreign bodies up to 1mm

is this to verify the level of ingress protection to fixed electrical equipment?

a) Gives the level of ingress protection for electrical enlosures.
b)
i) IPXXB -- Solid foreign objects ≥ 12.5mm
ii) IP4X -- Solid foreign objects ≥ 1mm

 

[gap30]

R =1.83m/ohm/m at 20C for 10mm 45A load 80 metres length of circuit
R=m/ohm/m x Length / 1000
R=1.83 x 2 x 1.2 x 80 / 1000 = 0.35136
R= 292.8/1000
R=0.2928
R = rounded up to
0.3 ohms
vd = R X I
vd = 0.3 x 45
vd = 13.5v
max of 5% 11.5 v so 13.5v not acceptible as greater than max

this is from a post by brucelee, tbh i am struggling with getting my head around this one a little, i cannot get the sums to add up

 

[JUD]

Resistance of 10mm² at 20°C is 1.83mΩ/meter

Circuit load = 45A
Circuit length = 80m

Total resistance at 70°C = (mΩ/m x 2 x Ct x L) ÷ 1000
Total resistance at 70°C = (1.83 x 2 x 1.2 x 80) ÷ 1000
Total resistance at 70°C = 0.35Ω

VD = IR
VD = 0.35 x 45
VD = 15.75V
VD > 11.5V (5%) so not acceptable

The 292.8 figure is the resistance at 20°C (1.83 x 2 x 80 -- no correction for 70°C) and is not used when working out voltage drop.

 

[brucelee]

soory Gap this was the only one that threw a spanner in the works for me when i did the exam i only knew how to work volt drop from mv/A/m x Ib X L /1000

I knew it was to do with ohms law so worked it out best i could and endd up forgetting to use the 1.2 for increase in resistance due to operating temp

jud is correct the total resistance is 0.35136 rounded down to 0.35
Vd = IX R
Vd = 15.75v and is greater than the 5%value of 11.5v so is unacceptable
so you can either increase Csa of conductor shorten length which will be almost impossible lol

If you work it out without the 1.2 correction factor then you will come up with the answer i did

I spent ages on this in exam as really was stuck rest of the exam i had done in 1 hr 20 spent 20 to 30 mins on it then rest going over exam again and this again

mate you have brought it all bvack to me lol

Now I know how to do it correctly as i spent the next few days going over exam on forum until i was sure I had done enough

 

[rick.oshea]

Gap,

I'm not sure if this has been mentioned (as 27 pages of posts takes some time to read through.....I got to page 9!) but time management can play a major part in the exam and place unnecessary pressure on you. I remember the feeling well!! As a lot of the guys have said, getting you mind right is going to play a major part in getting this nailed this time around.

I remember last year when I did mine, the first 2 questions in section 1 fried my brain, which put me on the back foot straight away (I'm sure they do it on purpose, mind you). I ended up wasting time on questions in section 1 and rushed section 2 where the main marks are.

The scenarios in section 2 are more relative to the work we do day-in day-out I found, where marks in section 1 can sometime be down to getting the wording & terminology exactly right for C&G.

On the day of the exam, try starting with Section 2, getting that nailed and hitting the weighted part of the paper and tot up the marks and then do section 1. Unconventional, but is a good way to manage your time productively relative to the weighted marking. It was a tip that was given to me after the event and in hindsight, probably would have been a better approach.

I hope this exam tip helps & good luck mate...

 

[gap30]

i have hit a brick wall atm with my studying, still so much to absorb, still dont fully understand tt installations with resistances and rcds ie Ra, been looking at q.26 on march exam 100ohm therefore 50/100 = 0.5 - definately one area i need to brush up on

 

[Sparky Ninja]

Hows it going in here? I thought as IQ is on his 'hols' I'd pop in and lend a hand. You guys have done an awesome job so far. :clap:

 

[gap30]

Hows it going in here? I thought as IQ is on his 'hols' I'd pop in and lend a hand. You guys have done an awesome job so far. :clap:

as i said earlier for some reason i have hit a bit of a brick wall, one test paper i can fly through, others struggle like hell!

 

[Sparky Ninja]

as i said earlier for some reason i have hit a bit of a brick wall, one test paper i can fly through, others struggle like hell!

I've PM'ed you .

 

[gap30]

I've PM'ed you .

thanks

 

[brucelee]

Gap you will be ok mate you cant know everything but you can give it a go and as i have seen your doing enough mate

I put similar effort in and like you and was daunted at first.The more i read practised the more I started to understand, You think you wont know enough but I am sure you will.
I am sure you will find like I did because of all the study fly through it but take your time to read the quetions at least twice before rushing in
any your stuck on just move on and try to answer at the end
then read through it all if you have time until that cert drops on the floor you wont be 100% certain
But as you have put everything into it like me sure you will be OK

how long before the exam