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. R

    Would you advise getting all the GN publications or is OSG + 7671 + GN3 enough??

    Just like the title really. I like the thought of getting all the guidance notes but is it worth it or would a copy of the aforementioned books suffice?
  4. B

    OSG, BS7671 regs book, Guidance Note 3, Testing & Inspection exam prep books for sale as a bundle

    Getting out of the game and want to get rid of these as i don't need them anymore. Paid £174 for the BS7671, OSG + GN3 bundle and £22 for the T&I Exam Practice book. Looking for £80 the lot. All in pretty much mint condition except the BS7671 which has some pencil markings in the contents...
  5. 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...
  6. 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 I know they’re out of date now but may be of use to someone?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...
  7. 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...
  8. O

    18th Edition & OSG - higher or lower - a bit of fun!

    So we all have to start parting with our hard earned monies CEF have just emailed me an offer of £94.95 (they say no VAT) Which is the cheapest I've seen so far .......... Anybody seen a lower price (or higher) :):):):) EDIT: The bundle isn't for both IET books the OSG guide is the NICEIC...
  9. M

    OSG, bonding plastic pipes etc etc

    Hi all Having a thumb through the OSG and on section 4.5 Main protective bonding of plastic services, it says there is no need to bond an incoming service of the service pipe is plastic....thats kind of a given....my struggle lies on the next page; "Where there is a plastic incoming...
  10. 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...
  11. T

    Regs books and guidance notes osg

    So I have my first cps assessment coming up just wondering if in this high tech modern world they do a pdf regs book yet. previously I’ve borrowed books and I have a green osg but I left the place I used to work at and I can’t really just borrow the books. It all seems a bit pointless with 18th...
  12. haptism

    RCD testing times BYB vs OSG

    Happy new year folks; just been looking at trip times as i need a photocopy for a client. Anyhow, in the OSG (page 112) for a general RCD, it states "with a leakage current of 100% the device should open in less than 200ms". However in the BYB (Table 3A, page 318) the table says device should...
  13. 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...
  14. haptism

    Table 7.1 Osg

    Hi all hope all is well and nice layout for the forum, like it. Been flicking through the OSG and notice that in table 7.1 (max cable lengths for final circuits) that there are no cb's or rcbo's rated above 40A. Is this because they feel like no ones interested in anything above 40A, am i...
  15. juice

    do you use the multipliers from tab 13 in OSG when calulating volt drop?

    I've recently done a C&G 2396 Electrical Design Course and unfortunately the tutor who taught the course did so for the first time and in my opinion didn't do a good job of teaching the material. I'm now doing my revision for an exam this Thursday and trying to make sure all the formula I use...
    • juice
    • Thread
    • cable conductor current osg table temperature volt volt drop volts when
    • Replies: 9
    • Forum: UK Electrical Forum
  16. 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 =...
  17. 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...
  18. S

    H2.5 osg

    Never noticed this before - H2.5 page 175 of OSG. would this mean you could have a 16a Circuit breaker spurred from a ring and then this feed a piece of permanently connected piece of equipment.
  19. 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...
  20. happysteve

    New OSG: looks like poo

    So, got my yellow On-Site Guide today. Quite a pleasing yellow cover. But inside... oh lordy. Looks like poo does when you've got a mild liver infection. Just horrible! :(

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