osg

osg

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  1. W

    Voltage Drop Calculation vs OSG

    Hi All, Hoping to get opinions on Vd calculations for a 1.5mm2 downstairs lighting circuit with an estimated length of 128m! Length is due to loops at switches (neutrals required) and switched lives feeding various strings of lights. Parameters: Mv/A/m - 29 ib - 2.38 L - 128 Method 1...
  2. C

    UK Why don't values in the OSG table I1 match those calculated?

    Hi everyone. I am really puzzled by this, but I suppose there is an obvious answer / reason! Anyway, Table I1 in the OSG says the mΩ/m value for copper with a CSA of 25mm2 is 0.727. However, when I calculate the R value using the formula: I get 0.688... Does anyone know why the values aren't...
  3. Lister1987

    Pimp my Regs / OSG / Other

    Those that have sat them before will no doubt have done it, tutors and the like will no doubt recommend they do and serving sparks will no doubt to it. Highlighting, marking and improving the usability of your regs (and/or other publications - OSG for example will make taking an exam (or just...
  4. P

    Free BYB and OSG, will post out

    Tidying my old van and garage up, got a mint condition big yellow book and a half decent on site guide, free to a good home if any trainee wants them? I know they’re out of date now but may be of use to someone? Either that or they go in the bin! Will post to first person that wants them (if...
  5. L

    Diversity allowance on sockets based on OSG

    Hi, Reading the on-site guide it’s states for socket outlets appendix A table A2 row 9 that 32A ring sockets in an office it can be 100% of the largest circuit and then 50% of the remaining circuits. However I have came across a calculation were the original designer has assumed that they know...
  6. Marti

    Standard symbols for electrical diagrams. Similar to OSG fly leaf.

    Afternoon Ladies and Gent's, I've got a level three assignment to add all the necessary installation symbols to a hotel and swimming pool. DB's, FCU's, switches et-cetra. Is there a standard for these or even a recognised set of symbols? I've searched as you would expect but there seems to be...
  7. CDB

    Diversity Table A2 OSG P118

    Morning all, Thumbing through the OSG guide today and I have a couple of questions regarding the above table. Firstly, just a idiot check but electric showers would fall into no.5 water heaters of the instantaneous type. I know this but so often doubt myself. Secondly, No. 9. Am I right...
  8. H

    Bs7671 v osg zs figures

    Why is it that the osg figures don't line up perfectly with the bs7671 figures for maximum zs? For example 16 amp type b breaker 0.8 x 2.73 = 2.18 in bs7671 yet osg says 2.2 Fair enough if they have just rounded it but they haven't rounded every one. For example 32 amp type c 0.8 x 1.37 =...
  9. happysteve

    Another OSG error I haven't seen mentioned... RCD and zones

    Eh up :) We all know about the duff max Zs tables in the OSG (Table B6) and GN3 (Table A4)... in fact, I've only just recently updated my GN3, and I'm pleased to say they have reprinted it and it now has the correct tables in. I've noticed in my (early-purchased, with dodgy table B6) OSG that...
  10. Richard Burns

    AMD 3 Zs tables and GN3 and OSG corrected tables

    For reference these are the Zs tables from BS7671 Amendment 3, provided by Amberleaf. I have cleaned up the scans a bit which is why they may look a bit odd round the edges. Remember IET have also issued the corrected tables for the latest GN3 page 121 table A4 and OSG table B6 which are...
  11. L

    max zs table in the osg

    Hi all sorry for this silly question but i cant seem to find the max Zs table for a 10A BS88-2 Fusein the osg. I can find it in the BGB table 41.4 10A = 7.19 ohms and i know to multiply it by 0.8 (7.19 x 0.8 = 5.75) for rule of thumb but i would like to find the right table in the osg
  12. H

    BS7671, OSG et al - Effective Markers and Referencing

    A bit of an odd one, I'll admit, but I'm relatively late in settling on a system of annotation to help me find common information fast and to cross-reference it for review. I know this isn't terribly exciting, but I'd be curious to hear / see how others have implemented their system, and what...
  13. R

    regs and osg

    Are the red books ok for a scheme assessment with the amendments printed off?
  14. jimbo81

    osg tables

    HI there this is my first post. im sitting my ACA soon and found all your posts very helpfull. Im having a few probs tho. When doing your ze if its 3ph do you test each and take highest result or an average or do you just test one phase and where is the table in the osg i compare the results...
  15. N

    Which is better OSG (Green) Or IEE Green for Periodic Inspection Reporting and I&T?

    Should I buy the new On Site Guide (Green colour) Or the IEE Wiring Regulation (Green) If I wanted to get more examples and explanations for Carrying out the new Periodic Inspection and Testing. Also would it containing anything regarding filling the Periodic Inspection and Testing Report with...
  16. kingeri

    OSG Table 7.1(i)

    Table 7.1(i) lists standard circuits that can be installed without calculation. The radial circuits are all listed as having a terminal load. Can they equally be used for socket circuits? Just to settle an argument!
  17. H

    Smoke alarms New OSG

    What page are they mentioned on. Cant find them in new one
  18. C

    Cable & Pipe Proximity - OSG Ref - Can U help?

    Dear All Can anyone help? Am working for the Bob "the know it all" builder on a re-furb and huge extension. I want to move some existing cables because they are touching and in some instances wrapped round hot water pipes. I know it's not specific in Regs re distances Sec 522, however have...
  19. M

    Model EICR in OSG contains mistake(s)

    Just noticed that the model EICR in the OSG contains at least one mistake ... Nominal Frequency filled in as 150Hz ... I sense an IET corregendum on the way.
  20. tank

    Max Zs in OSG and the Regs

    Hello all, i'm currently doing level 3 2330 and am getting a little confused with the different max Zs values in the OSG and the Regs. I'd appreciate any advice . Would i be right here I use the max Zs values in the OSG for installation design as these are lower to account for the reduced...

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