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calculating

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  1. B

    calculating 230V

    we make calculations based on a supply voltage of 230V, but in most installations the average is 245V. now a fixed load of 6 ohms would have the following current increases 230/6 = 38.3A 240/6 = 41.0A 250/6 = 41.6A my question is why do we use 230V when an average supply voltage is giving...
  2. D

    calculating design current in a ring circuit

    hello and thanks again for all your answers got another question for yous ok im trying to calculate design current for a ring if it was a shower unit say 7.5kw at 230 volts i would do 7500 / 230 = 32.6 amp this i no how to do cant think how you would do it for ring or even if you...
  3. S

    testing measured or calculated

    Hi guys, I have my part p assesment in about 4 weeks. I have a kewtech kt61, it does everything i need it to apart from pscc. Will i be required to perform a manual pscc test or will calculating it be acceptable? As my tester doesnt do it. Thanks
  4. K

    calculating csa of earthing conductor with BS1361 fuse

    Maybe I'm overlooking the obvious but how would you calculate the min. csa of an earthing conductor of say a tn-s system when there is no time/current graph for a 1361 fuse in the BGB? Do you just obtain If from Uo/Ze and then use this in the adiabetic equation. Ta
  5. O

    Calculating circuit load

    OK, got my tin hat on and have my running shoes on so I can to the bunker...... Looking at a customers "downlight" design for the kitchen/breakfast/family room. They have 32 lights marked and yes, they are planning on buying 240v x 50w fittings. Calculating load says you should use 100w per...
  6. B

    Calculating volt drop for >16mm cable

    Hello there. I'm trying to calculate the volt drop on cables that are over 16mm csa using the tables in BS7671. It's quite easy for lower sized cables, (length x design current x mV/A/m, if I'm right) but what happens when you go above 16mm and have a resistive component mV/A/m(r), reactive...
  7. A

    Cable selection, calculating earth fault loop impedance

    Hi guys, struggling to work this question out and don't seem to be getting a correct answer no matter what cable conductor size i use. Q. A 230V 14kW domestic electrical cooker, installed in a house is to be supplied by a 15m run of PVC insulated and sheathed cable, clipped to a surface. The...
  8. A

    Calculating design current

    Hi people, currently studying to become electrician and have got stuck on one of my tma questions. Q. A 16mm squared, two core armoured, 70 degrees C PVC insulated cable (copper conductors), is clipped direct to a surface, and forms the two wire radial distributor shown in the diagram below...
  9. S

    Calculating kva's

    Was wondering how others calculate kva's for electricity suppliers when requesting supplies. I use formula below but what are voltage figures now-a-days Kw x amps x voltage / 1000 = kva
  10. M

    Calculating Voc (STC) & Isc (STC) values

    I have taken the Voc, Isc and Irradiance measurements for my strings and entered these on my paperwork, but I do not know what values I am supposed to be entering for the Voc (STC) and Isc (STC) values in the Array Parameters section of my paperwork. Looking at the same paperwork from another...
  11. I

    Am i wrongly calculating my maximum demand?

    Hi guys i calculating my expected maximum demand for an installation to see if the 60A cut out will handle it. heres what will go in and calculations incl diversity 2X 32A Rings, so 32A(first ring) + 12.8A (40% all others) 1X 6A lighting, so 4A (66%) 1X10A lighting, so 7A 1X32A Shower, so 32A...
  12. D

    calculating battery size

    Chaps, This may be a little off the solar topic but maybe an off-grid expert can help? I've been asked to provide a battery powered heating system for a kennel. The heater is a 60W 240V device. He wants to run it for 10 hours a night and recharge the batteries every couple of days Can anyone...
  13. S

    Calculating Zs and PFC/PCS

    A little back ground to my quals first may help, i have a C+G2330, 17th ed and part p I am currently arranging for Napt to come out and assess me to allow me to cert my work. I've bought a tester which is calibrated in preparation for the visit as previously i have used testers belonging to...
  14. R

    Calculating voltage drop on larger SWA cables

    Hi All A question I've asked many a lecturer and none of them have come up with the same answer. When looking at the current carrying capacities for SWA cables, from about 35mm onwards you get an r, x, z value. What are these and which one do you use when carrying out voltage drop...
  15. S

    Design calcs, design criteria, or working drawings

    Hi all I'm in the process of joining elecsa part p and on my assessment day along with many other bits of paperwork they are asking to see a copy of the design calcs, the design criteria or drawings relevant to the work. When they say design calcs how much detail to you have to go into? Ie do...
  16. D

    calculating max zs values please

    hi chaps, could some bright spark help me out here, i have loads of periodics comming up and am getting fed up of looking up zs values for new and old MCBs, i kind of know the basic maths behind the values but could someone clarify how to work it out on site so max zs values for type 1,2,3 mcbs...
  17. M

    Cable size calculating program?

    Where can i obtain one?
  18. L

    Help with calculating the armour of SWA as a CPC

    Hiya guys. I am learning about earthing, bonding and cpc’s at the moment, and I am getting a bit stuck with using the armour of SWA as a CPC. Iwonder if anybody would mind helping me by reading this, and correct what I have got wrong so I can make sure I understand it properly. If I had a 2...
  19. O

    Calculating cable length from resistance

    I've noticed a number of threads regarding exam questions asking to calculate the length of a cable by measuring resistance. But I can't think of a practical situation where you would ever need to do this and seriously doubt the accuracy of the method. I know there are specialist cable fault...
  20. S

    Calculating R2 from R1

    Ive all ways for a bit of 2.5/1.5 Twin and Earth used this value 1.67 to calculate my R2 from my R1 values. 2.5/1.5= 1.66666666666666666667 so if i got my R1 as 0.34 i would expect my R2 to be 0.57 But the electrician i was working with disagreed with this and pulled out his onsite guide...

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