1. J

    Tri rated cable and grouping factor

    Hi guys I’ve got a motor starter I’ve come across and looking at the electrical drawings it’s originally had 35mm tails from a 100amp fused isolator switch. This has been replaced with 25mm tri rated cable. Looking at the specs for BS 6231 I can see the conductor can take 136 amps. Motors are...
  2. L

    Cable grouping factor Trimble software

    Hello, With regards to Trimble software for bs7671 cable sizing. I understand that a three phase circuit (No neutral) is one circuit and this can be achieved by 3 single core cables. Say for a “box” we have 5 single cables in parallel per phase (15 cables total) in Trimble for grouping purposes...
  3. M

    Power Factor correction of a Diesel GenSet

    Hi All, During my exercises on paper, we always assume the source from grid has Tension and Currentnin phase. Today, for the first time, I was learning about Diesel Genset and noticed its plate saying 2700 MVA / 2000 MW. So basically, somehow a source has its own Power Factor (PF). 1. Can...
  4. K

    Strange voltage and power factor values and installation issues

    Hi, We have installed 2 meters (each meter is a 3 phase meter) for sub-metering in a residential house (1 phase installation per apartment). One of the meters, after correcting installation, works fine now. The other one, in my opinion measures strange voltage values. We had since the begining...
  5. J

    Temp factor .8 and 1.2

    I have a new Metrel tester and it has a .8 factor to apply to ZS. for the temperature adjustment for the cable heating up from ambient as a result of a fault. I see .8 mentioned a lot elsewhere, is this .8 a rule of thumb derived from the equations of : rT= R20 {1 + A 20 (0-20)} =1.2 (inverse...
  6. D

    pure Nickel cable grouping factor

    Where can I find specific information on pure Nickel glass woven insulated Conductors for Cable grouping factors? I want to know the derating for 60cables @1.5mm in conduit 3 Phase
  7. S

    Can I avoid applying correction factor (Ci) when cable tray passes through a concrete wall?

    Hi This is about a design problem in an assignment. A cable basket containing several circuits passes horizontally through an internal concrete wall (100mm) and into a ceiling void where it provides lighting throughout the building. I'm trying to size the cables for the circuits and I'd...
  8. 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...
  9. 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...
  10. 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?
  11. 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...
  12. J

    When to apply 1.2 factor to R1+R2...

    I'm just trying to get my head round R1+R2 calculations (predicted rather than measured). All seems very straightforward naturally, however, I'm just after clarification of something. For the 1.2 factor that is applied to adjust the resistance of conductors to operating temperature, I just...
  13. P

    Diversity factor on rewire

    I'm going to rewire my house, and was wondering if it's ok to have 2 shower circuits as well as cooker, sockets and lights off 1 cu, or would it be better to have 1 of the showers on a separate cu, because of the available water pressure the 2 showers are never on together.
  14. 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?
  15. 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...
  16. 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!
  17. W

    Power factor unit

    hi Looking for abit of advice? We are quoting to replace some SWA cabling feeding various sub boards. I have an ABB power factor correction module in place, this is feeding a control panel in the plant room, feeding motors and ventilation equipment We need to replace the 2 x 150mm 4 core...
  18. 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 ?
  19. R

    What power factor to use for motor?

    Wondering what power factor to use when working out design current of an old 25hp motor. Nothing on its plate. It's been wired in with a 32D MCB, on 4mm three core SWA XLPE. Thanks.
  20. UKMeterman

    What is the power of this motor and ever seen one with unity power factor?

    What is the power of this motor, and would you consider it a quality product as declared on the label?