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  1. Lucien Nunes

    Using conduit as a CPC

    I have in the past installed using only the containment (conduit and trunking) as CPC. However, after a long discussion and analysis with my colleagues, based on real-world findings over multiple installations, we agreed that the number of examples of suspected and measured high-resistance...
  2. Lucien Nunes

    Laptop lid is tingling on touch

    The tingle you can feel is called 'touch leakage' and is a very tiny current, often a small fraction of a milliamp. From a proper safety-approved adaptor it is harmless and just an unfortunate side-effect of the design, which is intended to be equally safe and proof against causing radio...
  3. Lucien Nunes

    Non contact pen picking up current on water pipe

    Non-contact voltage detectors are versatile and useful but their behaviour is more subtle and complex than might appear at first glance. Their indications can be easily misinterpreted unless you understand about electric fields, which is perhaps why some people say they are unpredictable and...
  4. Lucien Nunes

    Replacing ceiling rose

    Depending on the construction of the new light, you might have to fit a new junction box into which all the existing cables terminate, with a single cable leading from there to the new light.
  5. Lucien Nunes

    Ethernet woes… hmmm what to do!

    Provided the pairs are not split, which would mangle the transmission performance. Pairs split the same way at both ends would test OK on a simple blinkenlights continuity tester, but fail to carry data.
  6. Lucien Nunes

    Moving cooker switch within prescribed zone

    Which is fine if they are good ones, fitted with the right tool. I've seen no-name yellows fitted with A.N.Other brand ratchet tool overheat at 30A, but you're probably bored of hearing me spouting about dodgy crimps in fixed wiring.
  7. Lucien Nunes

    Single pole rotary isolator

    It's an interesting point; from the point of view of final circuits controlled by a DP main switch or RCD in the CU, does the presence of a switching pole in the neutral negate the 'reliably connected to earth' that would otherwise be implied by the ESQCR? (Such DP switch being required by...
  8. Lucien Nunes

    Ethernet woes… hmmm what to do!

    @DPG's test is valid but you might be able to go one further, if you have a multimeter or continuity tester, and confirm whether the IDC connections to your cable runs are making contact as they are. Gently, without pulling too much on the wire, strip the last few mm of insulation from some of...
  9. Lucien Nunes

    Single pole rotary isolator

    Sorry I meant break all live conductors, not protective ones. Earthing must never be switched
  10. Lucien Nunes

    24V dc lighting circuit

    The wiring can all run at 24V, starting from a PSU and distribution point somewhere convenient. Beware voltage drop, which is 100 times more severe at 24V than 240 (10 times the current, but 10 times less total volts to lose) and ensure that the OCPD on the 24V side will work (although like...
  11. Lucien Nunes

    Single pole rotary isolator

    The current is unimportant, as you can get just as bad a shock from a 6A circuit as a 60A. On a domestic single-phase circuit, an isolator (which you would turn off to enable maintenance, for example) is expected to break all conductors with a 3mm contact separation. A control switch need only...
  12. Lucien Nunes

    Loft sockets question

    Unless the cable runs through thermal minsulation or is derated to an Iz of less that 20A e.g. due to high temperatures, use a 20A breaker. The 20A radial feeding sockets via 2.5 sqmm cable is one of the standard recognised configurations.
  13. Lucien Nunes

    Dimmer switch with discrete circuit

    These used to be available 30 years ago, MK and W&G both had a switch output as well as a dimmed one. Any modern dimmer with a physical switch should be moddable, although some might be easier than others
  14. Lucien Nunes

    Caravan Hook-Up RCBO Current Rating

    RCBOs and MCBs are not designed to be used for limiting consumption by users. They are designed to protect cables, and their characteristics match those of a cable. There is a ratio called the fusing factor, 1.45 for a standard MCB, that gives the lowest must-trip current for a given rated...
  15. Lucien Nunes

    300w power from auxiliary battery

    25A auxiliary load is possible for a vehicle alternator but it is a significant extra demand that will probably use up most or all of its spare capacity. A 2022 vehicle will probably have an energy-saving smart alternator controlled by the ECU, which can impact on the charging efficiency of the...
  16. Lucien Nunes

    Boiler circuit 16A MCB

    For fingers, no, but ingress protection also deals with dust and liquid ingress. One of the problems of holes in equipment enclosures / switchgear leading into a void or cavity is that they can cause a draught through the unit that fills it with dust as air leaks through the gaps around the...
  17. Lucien Nunes

    32amp Single phase rackmount distro

    Can't see the point of fusing anything down, not as though it would help limit tripping the overall supply. We have the old chestnut of whether all possible connected flexes including 0.75mm² IEC tails are protected against fault current (not overcurrent) by a C20, if you wanted that possibility...
  18. Lucien Nunes

    What is life as an electrical engineer?

    Don't panic! Once you start working on a particular project or activity, you can home-in on which areas of your existing knowledge are going to be most useful. You might want to revise them and/or pursue additional areas of study, but you'll have the underlying general resources and familiarity...
  19. Lucien Nunes

    32amp Single phase rackmount distro

    Don't forget inrush. What MCB curve do you plan to use and why? If I were using grey NAC3...B outlets with 4.8mm terminals, my preference would be to solder. I don't like 4.8's very much at all and certainly not at 20A, most are only 'rated' to 15 with a trailing wind. 6.3mm as used on True1's...
  20. Lucien Nunes

    2x4.8kw hot water with 1x4.8kw source

    As above, to decide the best interlocking configuration, we need to understand the priority requirements e.g. Cylinder A is always more important and must heat whenever there is both supply and demand, including cutting off cylinder B while it is heating. Any cylinder that is heating should be...

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