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voltage drop

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  1. C

    Voltage Drop Tolerances

    Hi I have been asked to provide power to a building at the foot of the customer's 30 metre garden (32A ring and 6A lighting circuits). When I calculate the required cable size in terms of voltage drop, 6mm SWA is just over limits. I am using 6.4 mV/A/m 36A Demand and 30 metre run...
  2. C

    Voltage drop on a ring?

    Morning, Just a quick question? In the OSG (2008) (page 44), it says that you can have 106 metres of 2.5 T&E with a 32A type B cb. Any ideas how they are working this out? My understanding of vd on a ring is mvam x half of length x half of ib / 1000 So 18 x 53 x 16 / 1000 = 15.2 v?? I assume...
  3. R

    voltage drop.

    6.9 v for lighting 11.5 for a socket. So my question is to calculate the size of a supply cable to a building that had lighting power heating for example. What figure would i use for voltage drop. Is there a wxtra safe rule of thumb method ppl use?
  4. A

    Calculating the voltage drop across a PVC insulated cable- 35mm copper conductor

    I am adding a new Air handler panel to a building and its load is 5421KVA. How do I go about getting the the start up current when the phase voltage is 240V? On obtaining the Start up current, now how do I calculate the voltage drop when the cable that I am thinking about using is the 35mm sq...
  5. T

    Voltage drop help please!

    Hi, i am confused about how voltage drop is worked out and need an answer for the following please; Work out cable size and cpc size you need when you have: Cable length = 50 metres Ib = 32Amps to get a voltage drop that complies with regs i.e. below 5%(11.5 Volts). It's wired in singles and...
  6. R

    Voltage drop

    Iv been calculation voltage drop. Could some see if what im doing is correct. So from looking in the regs i have found that your aloud 6.9v voltage drop for lights and 11.5v for sockets etc. S i take it that i need to go buy the 6.9 v as i have lights??? Im intending on feeding a new board...
  7. C

    3 phase voltage drop tables

    If you have a 50A 3 phase MCB, that's 50 per phase - when calculating voltage drop using the tables do you calculate using 50A or 150A? ie 10mm cable carrying 50A 3 phase over 30m VD=3.8x50x30 / 1000 = 5.7V or VD=3.8x150x30 / 1000 = 17.1V I think it has to be the first but am a bit mixed...
  8. E

    Voltage drop calculation format

    VOLTAGE DROP CALCULATION FORMAT hi my friends, is anybody have voltage drop calculation format? AND THERE BEEN SOME CHANGING OF OPINIONS AND ADVICES AS FOLLOW 1ST REPLY Shabu there's a few ways of calculating volt drop, the vast majority provide you with an "average" assuming the load is...
  9. D

    Voltage Drop issue

    hi guys trying to get the right table in the BS7671 book and the On site guide, regarding wroking out my CCC and VD.... I worked out my design for my shed, its going in twin and earth flat, in round conduit. Looking in the BS7671 it looks to me that is a Method B. There isnt a method b...
  10. S

    Voltage Drop

    Hi all, I've got a job to do regarding an outside supply to a summer house. The easiest route is to pick power up from a car porch. This small board is fed from the house on 2.5mm, which is approx 15m from the main board. Unfortunately the cable is under a driveway and simply installing a...
  11. N

    Voltage Drop

    We are all familiar with the requirements for measuring Zs and verifying that it is within the limits for the particular type of protective device. I use a single guide of 1.2 ohms as the maximum though there are of course many variations. What we (I) have not been noting is (R1+ Rn) and the...
  12. Golden_Boy

    Voltage Drop

    Why all the complicated formulea for working out voltage drop? Why not just connect the load and measure the voltage with a meter?:confused:
  13. C

    OSG Final Circuits voltage drop table question

    Just been flicking through and table 7.1 to enable final circuits to be installed without calculating voltage drop has one of the criteria as ii)The final circuit is connected to a dis board or CU at the origin of the installation Just seeing that I understand this and the reasoning behind...
  14. E

    Voltage Drop

    When looking for a new radial circuit for a extension i came across a cable that was used for the old boiler. So thought bingo use this. So checked the breaker and it was the correct circuit. I then put my mtr on it and i got 210 volts. Why is their a voltage drop ?
  15. S

    voltage drop

    Hi There, I wonder if any of you guys can explain to me why the voltages dropped across the choke and the flouirescent light dont add up to the supply voltage. I have got a little test to do at college where you have to measure the current and the voltage in a flouriscent light circuit , all...
  16. D

    Voltage drop

    Hi guys I wonder if someone can give me a bit of their advice. I have a customer who owns a medium size factory, he wants me to install a two sounders 230volt in an area so it warns people that there is a heavy vehicle coming, operated by a switch in the same area, by personel who are given...
  17. D

    voltage drop

    tested a circuit and its measured voltage was 218V. No where near the calculated VD. Any suggestions on what the Maximum permissable VD is . cheers
  18. I

    voltage drop

    with the value for volts Mv x Ib x l/1000 7.3 x 39 x 28/1000 = 7.97 V how can i comfirm this value is acceptable??? any help would be great :cool:
  19. T

    What is the voltage drop?

    Could you tell me what is the voltage drop across a 470W resistor conducting a current of 15mA? That is, if R = 470W and I =15mA, what is the value of V? Could you tell me how can you get the answer?
  20. H

    Voltage drop

    How do we calculate voltage drop on a ring final sockets only, Given the length of the circuit is 40 meters the cable is 2.5mm so therefore the amp per meter is 18, the mcb is 32 so is it 40 x 18 x 32 / 1000 = 23.04 but thats more than 5% = 11.5. Do we not use the mcb for socket outlets as we...

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