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adiabatic

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  1. Guitarist

    Supplies to outbuilding CU's

    Do you guys think that the majority of electricians actually bother using the adiabatic equation to decide whether the cpc of a T&E cable is adequate when supplying a CU in a garage/shed, or do most people just size the cable based on CCC and voltdrop? I come across a lot of T&E strung between...
  2. S

    Adiabatic Equation

    I am trying to get my head around the Adiabatic equation and was hoping that someone could check my understanding? I know the equation is S = √I² x t/k S = the CSA of the CPC I = the PFC which is calculated from Uo/Zs t = now this is where I get a little confused, my understanding is...
  3. M

    Adiabatic equation

    This one has always made me wonder !?? Does this work as simply for a 3 phase installation i.e 3.3kw over 230volts = 14.3 amps so does 3.3kw over 400volts = 8.8amps per phase OR is it 3.3kw over 230volts divided by 3 = 4.8 amps per phase ???
  4. A

    adiabatic equation

    Can someone please explain where to get the time (t) in the adiabatic equation i can work out the rest just need the (t) the MCB is a BS 60898 63A my PFC is 940A Thanks
  5. F

    Adiabatic formula

    Not got my reqs or on site guide with me today could some one explain or show me an example to work out earth size 230v supply ze = 0.12 customer been told about calculation rather than need to upgrade earth system and i cant remember formula or how to do it thanks in advance lads
  6. B

    adiabatic on earth bonding

    I'm trying to get my head around using the adiabatic to calculate minimum size earth conductors and realised I am getting myself confused over which fuses they relate to and how they relate to the tables in the OSG. This is a theoretical situation, I am just trying to make sure I understand...
  7. L

    adiabatic equation

    so you use the adiabatic equation to work out the cross sectional area of a conductor the fomula is obviously S=(sq root) of I2xt/K can someone give me some numbers so I can work out the answer useing this equation as I want to make sure i know how to do it.
  8. S

    Adiabatic equation and bonding

    Can somebody have a look at this and tell me which tree I'm barking up? Using the Adiabatic equation to determine the required size of main bonding and therefore the size of supplementary bonding. Ze = 0.18 PFC = 1.3 kA Fuse type 1361 IIa S = square root (1300 x 1300 x 0.1) /115 = 3.57...
  9. B

    imperial cable & adiabatic equation

    doing pir before cu change. property built 1968 imperial size cable all test results ok. just one circuit is bothering me and i maybe looking into this too much but radial circuit, which originally was for an electric old type two bar fire as informed by owner who lived there since it was built...
  10. H

    help on pirs

    Hi all, Completed my first pir yesterday (: now this client has got a three phase supply, TNS which feeds a ground floor shop and a flat above, the flat has a on peak and off peak supply. With the tails for the flat going into two kmf switches with a sub main cable of only csa of 10mm T+E for...
  11. S

    adiabatic equation help!

    Hi all i was wondering if anybody could shed some light on this equation or part of it. I think i understand how to work out the equation its self but its this part i dont understand. In order to apply the adiabatic equation we first need to calculate the value of I (fault current) using this...
  12. R

    Adiabatic equation calc

    can anyone help I want to calculate a main earthing conductor for a three phase supply using the old adiabatic equation. I'm struggling to work out what value of I to use. If you use 230V/0.35 (for a TN-C-S) then you get 657 amps.... if it turns out that Ze is lower, the fault current is going...
  13. F

    Adiabatic- bonding

    Hi people, I'm not the best at math but I'm trying to figure out what size cpc for water bonding I can calculate. Tns system Ze 0.18 PFC 1.52kA t=0.1 sec K=143 8 metres in length Main fuse= 80a, type 2, 1361. It is currently a 6mm cpc but I can't replace it due to floors and new kitchen! I'll...
  14. 2

    Adiabatic Equation

    Hi Is it acceptable to use the adiabatic equation to work out the size Main Earthing conductor to install in a standard domestic property for a consumer unit change. Ive always been under the impression that its 25mm tails and 16mm main earth for a tns or tncs system, but a colleague...
  15. W

    Adiabatic equation help

    Hi chaps, Can someone please give me a quick lesson on adiabatics? When to use the equation, detailed description of what it is etc. Been scouting any literature i have here but not been able to pin something down. Thanks B
  16. i=p/u

    adiabatic

    yo, fittering about here tell me if im right. example: identifying the minimum size of cpc required to ensure protectionfor copper conductors protected by say 50A tybe b mcb to . so 250x250x0.4=25000 sqare root= 158.1/ 115=1.37.. so is this correct by multiplying type b by 5? and my 50A...
  17. P

    adiabatic equation reg 543.1.3

    Can any one help please on a tncs system (PME) 100amp main fuse bs1361 100amp I am trying to work out the maths for the earthing is there a simple way all looks a little confusing S is the csa of the conductor 25mm I is ??? t is page 244 the table says 630A K = ?? so 630A squared x 5 (5sec...
  18. G

    Example of use of Adiabatic Equation.

    Many thanks to 'Dave_' for posting this example originally in a thread. Minimum Size of CPC Here I will calculate the minimum size of CPC in accordance with regulation 541.1.3 of BS7671. Primarily I will need to calculate the minimum size of CPC (or confirm the armouring is adequate) of...
  19. T

    Adiabatic Equation

    does anyone know what the current limiting class 3 means on an mcb, for eg does this mean a max of 3ka let through energy ? if it does it makes a difference when using the adiabatic equation for sizing cpc`s
  20. B

    adiabatic test of mian bond

    Hi all have tested a flat were the main bond is only 6mm the incomer is 1361 60A main earthing conductor is 16.oomm doing the adiabatic calculation what disconnection time would i use to assess if this conductor is man enough (and yes i know it should be 10.00 but the customer want have any...

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