1. J

    Grouping factor for JB

    Opened an IP65 JB surface mount box today (internal conservator) 2 lighting circuits including Switch cables and radial feed from last light all coming into the box. All fitted ok and all secure with Wago connectors no strain on connections. My question is would you need to apply grouping...
  2. marconi

    what discharge lighting factor to use for hf flurry luminaires?

    I have been helping out a fellow with his lockdown assignments. One of the questions was about design. There were 60 or so high frequency electronic flurry luminaires each being 58W. The question was to work out the design current. In the feedback on his first attempt his tutor said he had...
  3. S

    Australia Diversity Factor for 3Ph instantaneous Hot Water in AS3000

    Hi, Just a question from AS3000 max demand diversity table C1 for instantaneous hot water. Will it be the same diversity regardless if it is 3Ph or 1Ph or higher current rating or less?
  4. Lister1987

    Trainee Component Form Factor & DIN

    Excuse the ignorance here but why do we have all inserts (RCD/RCBO/SPD etc) and the only thing that is constant address every make and type is a DIN rail? Why are the sizes not universal allowing cross-brand usage, I mean a Wylex RCD should function the same as a Hager etc and yet you get some...
  5. lurch

    Rating factor within an enclosure?

    I seem to recall there is a rating factor that can be used within an enclosure effectively uprating the current capacity of the cable. Does any one know what this is and can it be found in BS7671 or is this a rule of thumb (?) for switchboard manufacturers?
  6. Gary Tollison

    loop impedance, temperature, cable factor....

    Hello I'm not sure if this is the correct forum area to post this in, apologies if it isn't... I've been working through some mock questions on-line, and found myself confused by this: The measured value of loop impedance for a circuit is 0.83ohm. If the temperature at the time of the test was...
  7. E

    Ci - for cable calcs

    Also just revising: trying to apply a rating factor for insulation on a cable calc. Just in theory, it's not for an actual job. The cable will be clipped direct to joists above ceiling and is covered in >100mm thermal insulation. I cannot find the correction factor for insulation. Advice please!
  8. haptism

    BS 1361 50A ZS

    Anyone know the ZS for an 1361 or BS 88-3 50A fuse. All the tables I find have n/a. I phoned the maker and was told there are no listed ZS' for a 50A and to take the difference between the next closest sizes (45A & 60), surley thats not proportional ?
  9. 0

    3 phase cable selection and protective devices

    Hi everyone. I'm after abit of help calculating cables sizes and protective devices for a 3 phase DOL motor. I haven't worked on 3 phase equipment for many years and 3 phase calculations is as far back as college so please excuse my ignorance on the subject and not knowing answers to perhaps...
  10. A

    Industrial Calculating power factor with wattage and voltage

    Hello, I really need to know if it's possible to calculate the power factor from the voltage and the wattage... For example... 13kW, 400 V three-phase machine Thank you
  11. P


    Anyone know the Power factor forula required for the AM2 motor starter? Really desperate!:omg_smile:
  12. V

    Generator formula

    Hi everyone, I am looking to know the formula for KW to Kva and any other related formula that you would know thanks v
  13. shnabz

    2365 Level Drawings

    Does anyone have the 2365 Level 3 Drawings on a pdf file they could share with me? My college have been re-using old ones and the quality is horrendous, they have probably just been printing copies of copies. They are not very good when it comes to computers and won't give me access to walled...
  14. R

    Multiple 3 phase motors fed via a JB supplied with a 27 core SWA

    Looking into a site today, just changing an isolator, i found multiple motors are supplied via a 27 core SWA cable. The motors are only 1-3kw and are supplied as follows... Main panel ---(27core SWA)----JB----(7core SWA)----Motor The 7 core includes an isolator signal for control purposes. I...
  15. spud1

    Calculation of grouping factor for 3 phase tails

    Hi, when determining a grouping factor for a galvanised trunking containing 3 phase tails, and when consulting table 4C1 BS7671 to determine the factor does each phase/tail count as a seperate circuit or are the tails considered in themselves one three phase circuit? Thanks
  16. A

    Help With Circuit Design

    Guys, I have an assignment which I am struggling with but which should be easy and have read loads of books I keep going around in circles. Can you please put me back on the tracks. The task is for the design of a RFC in a garage with the routing clipped a few centimetres below the ceiling and...
  17. N

    LED vs Fluorescent

    Hi all, I have been asked by a local community centre for some advice changing some faulty 6ft strip lights to LED. As far as I can see 6ft LED tubes are Twice as expensive as replacing a ballast and tube but half the wattage (i.e. half the running costs). does anyone have any experience with...
  18. K

    Earth Fault Loop Impedence question

    hello, i got this qustion and would like someone to show me the working out of it please. the measured value of loop impedance for a circuit is 0.83 ohms. if the temperature at the time of the test was 20c and the cable is 70c (factor1.2), what is the correct value. ze = 0.4 ohms
  19. T

    Domestic pvc trunking limits?

    just a thought, i have been using some maxi trunking to suply cu going verticaly down the wall was wondering how far verticaly can you go with trunking before you need to support cables? also how do you judge how many cables to put in?
  20. C

    Cable factors in trunking, conductors over 25mm^2.

    Hi All, I have been searching the forum but can't find this anywhere. Can you please see if my interpretation of this is correct: 50x50 trunking, 2m run with 1 90o bend. 4 x 50mm conductors, 1 x 35mm conductor. As there are no factors for over 25mm2 I have to work it out manually 50x50 =...
  21. sythai

    Conduit cable calcs....help please ?

    Just calculating my In... conduit with singles run. For the grouping factor - Cg it states number of circuits If I have 2 circuits, but this consists of 18 x singles (e.g 1 x ring = 6 and 4 x radials) Would this still be a factor = 0.75 ? Thank you Sy
  22. S

    3 Phase cable sizing help?? Proceedure?

    i'm after a little help with cable sizing. I have tried reading my IEE design guide, and still struggling to get to grips with the correct proceedure to follow for sizing cables. I have always struggled a little with this, but thus far my knowledge goes (albeit shaky)... It>_ In/(Ca x Cg x Ci x...
  23. B

    200 x 200 trunking capacity

    What is the maximum cable capacity (factor) for 200 x 200 steel trunking 2metres up the wall with a 90 degree bend three metres along the wall And what is the cable factors for 1.5mm and 2.5mm singles Don't have reference books to hand
  24. L

    RLC Circuits - Phasors

    Hi Guys, Just wondering if anybody would mind explaining the main purpose of working out the lead/lag of current compared to voltage in RLC circuits? Is it to do when selecting/derating cables for current carry capacity? Is there any other things that happen? maybe extra heat build up in...
  25. J

    volt drop rule of thumb

    Hi Guys, could anyone explain to me the 1.2 volt drop rule of thumb? i understand the 3% for lighting and 5% for other circuits. any help would be welcome studying for 2391. Thanks in advance.
  26. K

    Generator shutdown

    Hi Folks! Wanna ask some help. I have a KOMATSU Generator with capacity of 350KVA, 220V, 3phase. When I was recording the data from a HOIKI power analyzer, I noticed that sometimes the current reading on the GROUND line reaches to 40Amperes. What could be the cause of that measurement? Before I...
  27. S

    Ring Final Circuits & Correction Factors

    Something I've wondered about for a while... If you had both legs of a RFC, in say T&E or singles, running in the same conduit, so basically touching, would you need to apply the appropriate correction factor for grouping?
  28. S

    Commercial 350 KVA HV Transformer? 3 phase calculation confusion

    I need to buy a 3 phase HV transformer for an apartment block 1382 Amps is the total predicted single phase load after diversity. 1 Phase KW 1382 Amps 230 Volts ( I/V) 317.86 KW KW 1 Phase KW to KVA 317.86 KW 0.9 Power factor ( KW x P.F. = KVA) 353 KVA KVA Single Phase to 3...
  29. T

    3 phase motors ratings

    Hello you clever motor men ive not had a lot to do with motors, what I would like to is if for example a 3 phase motor is quoted as 6kw (forgetting the kva and power factor for a mo) would it normally mean 6kw overall or 6kw per phase ?
  30. C

    Circuits on phases

    Hi I was wondering if anyone could explain about circuits on phases, on sites that I work on we r given drawings with lighting circuits and power circuits and I get told we need to keep certain circuits on certain phases but dnt knw why, obv you have exp L1 L2 and L3
  31. E

    Volt Drop Calculation

    Appendix 4 in the regs has tables for Current-Carrying Capacity and Voltage drop. I've used these many times with no problems, but i've never had to calculate a cable higher than 25mm. when you look at cables 25mm and higher you see three values for mV/A/m (r, x, & z). Using the calulation...
  32. B

    shower cable

    9kw shower to run on a 6.0 swa clipped direct for 30m but for 2 metres it goes through a boiler rm so what is the min amount you guys whould take including a temparature factor in calculation although these results are addiquite i will be running 10.0mm but am i being over the top any thoughts
  33. S

    grouping factors in metal trunking

    hi everyone got a querry regarding above. through approx 1.5m om the installation all the main cables run through a 4" x 4" metal trunkning, was wondering if anynone is knowledgable at working the grouping factors out?? got a lot of pvc/pvc running though cheeers
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