Continuity Of R1 & R2 Conductors

[Dal Roberts]

circuit 1   -  5 metres in 6mm line /2.5 cpc and (using table i1 page 182 on site guide) i have a resistance per metre of 10.49, i have a measured value of 0.05 ohm , with this information how would i work out the tabulated value of R1 and R2? what formula. I'm in 17th edition training and have lots of circuits to work on but am stuck at the formula, any help would be appreciated so as to work out the rest 

 

[NozSpark]

Looks correct to me,, double check your units

 

[Dal Roberts]

the (table i1) as forementioned is a combined resistance of 10.49 for 6mm/2.5 cpc ? Mohm/per metre , I've not physically tested this, its just the question. , how would you guys calculate this , i.e. next question which i do not want the answer is a circuit: 8 metres line/cpc 4.0 / 2.5 and measured value as stated on the question is 0.12ohms

As i see it , little r1 and little rN (which should be the same) divided by 4 gives me 0.625 for r2, then little r1 + r2 divided by 4 = 0.78 Ohms. hopefully from the information in the question my method was right!

 

[Dal Roberts]

thanks for your help very much appreciated too 

 

[poni]

???

is it not R1+RN /2 = R1 then R1+R2 -R1= R2

IE R1+RN = 4

4/2 = 2 = R2

R1+R2 = 3

3-2 = 1=R2

R1=2

R2=1

 

[zimmy]

No sure why you would want the RN value unless of course you are looking at a ring circuit.  But to calculate the Zs you'll need the R1+R2 value per M then the length of run  Use the correction value and add that to Zdb or Ze as required to give calculated Zs

To find the length or run from a given or stated R1 +R2 of  say 2.3 Ohm, then divide the given value by the value per meter from the table.

To be honest here, your lecturer/ tutor is being paid to explain this and if he/she isn't then they need a kick in the naughty bits  

 

[Nicky Tesla]

dont know what all that calculated malarky is above but,

6mm   estimate at 0.01 per metre.............which is R1 (L) going to the cooker (for eg), and the R2, the cpc coming back

therfore your 0.05 for 5M  IS   your R1R2.......(.5 x 0.001049)

you also have separate conductor sizes in your table so you can work it out separately if you require.

 

[Windpasser]

No sure why you would want the RN value unless of course you are looking at a ring circuit.  But to calculate the Zs you'll need the R1+R2 value per M then the length of run  Use the correction value and add that to Zdb or Ze as required to give calculated Zs

To find the length or run from a given or stated R1 +R2 of  say 2.3 Ohm, then divide the given value by the value per meter from the table.

To be honest here, your lecturer/ tutor is being paid to explain this and if he/she isn't then they need a kick in the naughty bits  

Its not always possible to teach some students in a classroom environment as its often too close to the school classroom ethos and experience. These students need to be out in the field and learn by asking the relavent questions at the relavent time. - don't you think?

 

[Nicky Tesla]

No!    school is different cos not everybody wants to be there and they cannot be dismissed.  

 

[Windpasser]

No!    school is different cos not everybody wants to be there and they cannot be dismissed.  

Believe me school is not so different for a 16 year old apprentice signed up for his first year at college. But they tend to grow up a little quicker when their bosses are on the case...

 

[zimmy]

Oh well, that sums it up then.  And qualified electricians rip into 5 week wonders!

 I'm not sure what the hell the young people are being taught these days but from what I can see they are being instructed by clowns.

 

[binky]

have to say the college courses seem to be just stupidly long winded, you could condense them into a year in my opinion, theory and 'working on boards'. Real world experience to back that lot up with is what is really needed.

 

[ranaroo]

Hello, try this to answer your problem

R1+r2 = 0.05 ohms (6/2.5) measured value.

Therefore

r1(6mm) = 2.5/6+2.5(8.5) X 0.05 = 0.01470588 ohms

r2(2.5mm) = 6/8.5 x0.05 =0.03529412 ohms

Check total

0.01470588+0.03529412= 0.05 ohms. (your reading)

 

[zimmy]

Regarding the time taken in college.  Within five weeks (the legendary 5WW) it is possible to get from zero to hero.  (Sort of).  I'm not saying that is a good thing or a bad thing but, it is possible.  I have seen it.  From no idea what an Ohm is to sitting, and in some cases passing, the 2394 and on occasion the 2395.

(And please don't even think of saying the 2395 is a watered down 2391.  It isn't as I have done them both - and the 2394)

From an electrician and tutor/assessor point of view I find it far better to teach theory in the classroom and practical in the field. You have to have done both to really get a handle on that one.

binky, would you really want someone to practice on your home?  Get it right on a work-board and you'll have a fighting chance in the real world.

 

[binky]

Think that's what i said, but condensed into a year. No board is ever going to be like a house hence real world training is needed.

 

[kerching]

I am surprised at the number of new "sparks" who cannot remove a floorboard without it looking like it has had a night out with a couple of 70s TV personalities

Just saying

 

[zimmy]

I think what you said is the reverse of what I'm saying binky but I get your drift.  Some courses are dragged out (or so it may seem).  Some are long-winded to ensure you have enough time to digest and understand the theory (He/she may get it in their heads a lot quicker than me as I'm a thick sod)

At Access Training Cardiff the 2396 (level 4) is conducted over 5 days.  This IMHO is way too short a time as it is what it says on the tin... a bit hard to get your head around in 5 days, and unless you really know what you're talking about it is a Lulu.  The project is fun to be fair and you really need to think about it.  The year I sat the bugger - (as was 2400) -  Swansea College thought it was a closed book (all the other years they ran it they used open book, bastards!) and unlike other years my class did it as closed with just 15 mins notice!  It turns out that (according to what I've heard) it is now and always was open book!  Other training places take an academic year for the 2396.

I'm saying that Part P is what it is and should be a dam sight tougher to have any sort of credibility.  Part P should included, as a minimum, the 2392 fundamental testing ticket and not the bloody pure crap it is at this moment.

 

[Sidewinder]

The 5WW courses are fine for the original target market, trouble is their entry criteria has been opened up way beyond that of the original remit.

It's all about money, not safety remember.