calculation | Page 9

calculation

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  1. W

    Can anyone help with another calculation please ? lol

    Right, this time it is on capacitance... now the equation is simple enough & im sure iv got it right and come to the right awnser in the process however, im pretty sure my tutor said there was a way of making the number that you get back smaller, but i cant remember what he said. For instance...
  2. W

    Can anyone help with a calculation please ?

    Hey. Basically, we are doing alot of calculations in college at the moment on resisors in series and parallel circuits. Iv pretty much got everything down apart from calculating current in the parallel branch of the circuit. I have a couple of ideas which may be the way to do it, "or not" im...
  3. C

    Calculation help needed!

    Hi all with regard to BS 7671 page 48 (411.4.5) can someone tell me in plain English how to do these calculations. As I am trying to calculate the following question: The fault current due to an earth fault of neglible impedance in a 400 V three phase, four wire circuit having an earth loop...
  4. C

    Calculation help!

    Hi, With reference to BS 7671 on Page 128: Using the mathmatic formula can anyone tell me how to punch in a calculator the workings out of the following: When calculating the minimum cross-sectional area of a protective conductor, the following is available: Fault current = 650A Op time...
  5. K

    *Voltage drop Question Calculation help*

    Hello guys looking in, Just want to make sure i'm doing this right as i'm still a bit fresh, This is the senerio as follows, Single lighting circuit from a 230v supply on a 10 Amp MCB. 1.5mm PVC Singles total length from board to furthest point 40 metres. 1500 total watts of various...
  6. B

    Cable Calculation

    Hi, I was looking through old exam papers and came across the following question; A 2-core distributor cable of uniform csa is loaded as follows: Point B = 30A Point C = 90A Point D = 62A The cable is supplied at End A at 229V and at End E at 231V. The resistance of the cable is 0.01...
  7. D

    prospective earth fault

    if you were to work out the value of the prospective earth fault by calculation at point of the supply, what values would you need to do this calculation :confused:
  8. S

    3ph + E Zs calculation?

    Can anyone tell me how to calculate the zs in a 3ph+E installation as my tester will not give me a reading. I've looked into it and a special loop tester is needed, if this is right? Thanks Paul
  9. E

    Volt Drop Calculation

    Appendix 4 in the regs has tables for Current-Carrying Capacity and Voltage drop. I've used these many times with no problems, but i've never had to calculate a cable higher than 25mm. when you look at cables 25mm and higher you see three values for mV/A/m (r, x, & z). Using the calulation...
  10. A

    formula and calculation aid section

    Wondered if it would be of use to have a formula and calculation aid section, ie fill in the blanks and get the answeer type thing. :) Dont know how difficult it would be to do :o Any opinions?
  11. S

    length of circuit calculation - head scratching stuff!

    Hi all, How do I work out the length of a circuit? I have these figures R1+R2 = 0.40 The circuit is wired in 2.5mm/1.5mm T&E I take it I need to know the resistance of the T&E (where do I find this?) Could someone give me the formula or point me in the right direction Thank you.
  12. D

    Adiabatic calculation confirmation

    Could anyone just confirm my results for adiquate earthing size and calculation using the adiabatic equation... My test was on a ring main circuit wired in 2.5/1.5 pvc.. My supply voltage is 247v My Impedance is 0.38 ohms. The circuit is supplied via a RCBO 32a C type My results suggest that...
  13. R

    Calculation of ZS

    Evening guys When calculting ZS u us the formula ze + r1 + r2 So i have 0.18+0.60+1.00 = 1.78 But i also have my r1+r2 result which is 0.40 0.18+0.40 = 0.58 so which 1 do i use then? Cheers guys. :)

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