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  1. ELECNEWT

    advice required On beam strength loss

    Just to clarify, the formula I referred to in my post was purely to highlight the effect of reducing the depth of a beam as opposed to the width. To carry out any valid assessment of the effect of a notch or notches would require lots of data, advanced techniques and relevant expertise...
  2. ELECNEWT

    advice required On beam strength loss

    Yes. Now I can move on the IET forum and lurk there.
  3. ELECNEWT

    advice required On beam strength loss

    The strength of a rectangular beam loaded in the vertical direction depends on the second moment of inertia I. Where I= B*D(cubed)/12 . Where B is the width of beam and D is the depth. You need to know the exact dimensions but as an example: for a six-inch-deep beam with a one-inch- deep notch...
  4. ELECNEWT

    45A breaker max Zs values

    On certs I tend to state the corrected value for max Zs and put a footnote to say what I've done. To me this makes sense because further along you have your actual measured Zs and hence you get a quick cross check that your circuit complies. The question of whether to put corrected or...
  5. ELECNEWT

    45A breaker max Zs values

    In addition to C min (0.95) to take account of voltage variation, do you have to incorporate a factor of 0.8 for temperature effects? I.e. 230*0.95/ 5*45=218.5/225 =0.97 But to account for temperature effects the corrected value of Zs is 0.97*0.8 =0.77 ohms.
  6. ELECNEWT

    I never install ring circuits, the potential for danger is unacceptable

    Thanks .OK with that.
  7. ELECNEWT

    I never install ring circuits, the potential for danger is unacceptable

    I am interested as to why 4mm radials with 32 amp breakers are unlikely to comply. Not arguing just interested.
  8. ELECNEWT

    SWA CLEATS IN WOODEN GARDEN SHED

    Is there any requirement or logic to using fire-retardant cable cleats for SWA inside a wooden shed? There will be a 2 metre vertical run and a 3 metre horizontal run of 4mm 3 core SWA.
  9. ELECNEWT

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

    Strima, thanks for putting me right.
  10. ELECNEWT

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

    Are there two factors: 0.8 for temperature effects and 0.95 for voltage variation? Giving final figure of 0.76?
  11. ELECNEWT

    Great Quotes...............

    “I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind” Kelvin.
  12. ELECNEWT

    Testing RCBO at Light Switch

    Telextric, as I understand it, you are saying that testing at the switch is acceptable but that testing at the outgoing terminals is preferable. Do you think there is ever a case for using both methods?
  13. ELECNEWT

    Testing RCBO at Light Switch

    Is it acceptable, using a two-wire RCBO tester, to test at a light switch using the phase and earth wires? If it is acceptable are there any disadvantages?
  14. ELECNEWT

    Help needed with understanding IR

    Sorry Tel. I did not mean to give you a dumb. I was actually trying to give Pete a like. But I was doing it on my cheap smartphone with big fingers. I agree that the product over sum method is very cumbersome and prone to errors.
  15. ELECNEWT

    Help needed with understanding IR

    I always thought that the Product Over Sum method only worked for resistances taken two at a time. For resistances 10 20 30 and 40 ohms in parallel. For the first pair 10 x 20 / (10+20) =6.666 ohms For the second pair 6.666 x 30 / (6.666+30) = 5.454 ohms For the third and final...
  16. ELECNEWT

    Removing small section of coving

    So ideally I want to remove a small section of coving and then replace it. Note: I am only running the cable vertically through the coving. Don't remove any coving. Instead cut a channel in the plaster behind the coving. You will need to do this from the room and from the upstairs floor...
  17. COVING.JPG

    COVING.JPG

    • ELECNEWT
    • Media item
    • Comments: 0
    • Category: Electrical Videos
  18. ELECNEWT

    - RIP Jim Bowen - Bullseye

    Between 1999 and 2002, Jim Bowen presented a live morning magazine programme on Radio Lancashire. He resigned after making an allegedly racist remark on air. He said someone was a "nxxnog", a common expression in the day meaning someone who was stupid. It was was not meant racially but the PC...
  19. ELECNEWT

    Hole in joist - question on span

    I'm sure you were only exaggerating to illustrate a point, but his house would fall down fairly quickly. If you halve the width of a beam you reduce its strength by a factor of two If you halve the depth of a beam you reduce its strength by a factor of eight If you halve both width and depth...
  20. ELECNEWT

    Equipotential Bonding Explanation

    Thank you again Richard. You have been an excellent teacher on this topic and a model of patience.

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