Resistance calc

[Nijinski001]

Am I reading my tables right?

Guys - I am embarrassed that I am asking this question.

I am trying to get up to speed on I&T before going to take CG2391.

Continuity testing on 1.5mm T/E. A reading of 1.24 MOhm according to my calculations is approx 41mtrs of cable. My mentor says it is less than that and has asked me to go away and re-think/calculate.

My tables (9A OSG) say 1.5/1.0 T/E is 30.2mOhm/metre.

Where am I calculating wrong?

 

[Diyisfun]

24.35

 

[Albert]

Am I reading my tables right?

Guys - I am embarrassed that I am asking this question.

I am trying to get up to speed on I&T before going to take CG2391.

Continuity testing on 1.5mm T/E. A reading of 1.24 MOhm according to my calculations is approx 41mtrs of cable. My mentor says it is less than that and has asked me to go away and re-think/calculate.

My tables (9A OSG) say 1.5/1.0 T/E is 30.2mOhm/metre.

Where am I calculating wrong?

1) 30.20 mohm/m is correct
2) If you pay attention you will se that the resistance in table 9A is in mohm=millie ohms, so your reply can't be in Mohms=Mega ohms.
3) I think that you forgot to divide the result by 1000 to get it in ohms.
4) or you could leave it as 1238.2 millie ohms, but it does not look nice.
5) I don't know whether it was mentioned but it is required to multiply this by 1.2 to find the maximum resistance when the cable will work under maximum operating temperature see table 9C

 

[ban-all-sheds]

millie ohms

Lovely girl. I knew her mother - fine figure of a woman, I could never resist 'er.

Where am I calculating wrong?

Have you got 41,000 km of cable?


Sorry - just jesting, not poking fun - hope neither of you are offended...

 

[Albert]

millie ohms

Lovely girl. I knew her mother - fine figure of a woman, I could never resist 'er.

Where am I calculating wrong?

Have you got 41,000 km of cable?


Sorry - just jesting, not poking fun - hope neither of you are offended...

I just checked your record and you still are on the positive with your replys.. so one (or ten) silly ones will not change the balance, but be careful...

Any remarks on this one or I passed clean this time...

 

[Nijinski001]

No offence taken BAS.

I realised my decimal point error after posting. Even an incompetent like me wouldn't dream of putting 41,000 mtrs of cable in a house. 25,000 is my limit!!

As the font of all knowledge any ideas where the 24.35 came from in the second posting?

 

[ban-all-sheds]

IHNFI

 

[Nijinski001]

Good - I thought it was just me.

 

[Diyisfun]

I know where it came from

Are you interested in how it was calculated?...To save another posting it was not noticing different units of measure.

 

[Nijinski001]

Continuity testing on 1.5mm T/E. A reading of 1.24 MOhm according to my calculations is approx 41mtrs of cable. My mentor says it is less than that and has asked me to go away and re-think/calculate.

My tables (9A OSG) say 1.5/1.0 T/E is 30.2mOhm/metre.

I don't understand. Where are the different units of measure?

 

[ban-all-sheds]

I don't think you can use a "difference in units of measure" to explain away a completely barmy calculation of 30.2 ÷ 1.24.

Whatever "units of measure" are used, that formula would mean that as the resistance of the cable increased, its length would decrease....

 

[Diyisfun]

It has been pointed out

If you pay attention you will se that the resistance in table 9A is in mohm=millie ohms, so your reply can't be in Mohms=Mega ohms.

I am not a sparkie I am a DIYER

 

[Nijinski001]

Thanks for that. As both Albert and BAS pointed out and I had already noticed after posting the decimal point was a little astray. It should have been been on Ohms not MOhms.

I still don't understand where your 24.35 comes from in your original posting?

 

[Diyisfun]

It looks like this could haunt me...Ok .. on who wants to be a millionaire, its who answers first, so you answer, realised you Fup & hope know one else gets it right, but then wished you had thought a bit more.

how many more

 

[Albert]

I don't think you can use a "difference in units of measure" to explain away a completely barmy calculation of 30.2 ÷ 1.24.

I am impressed!, where do you find the time to find where this number came from...