circuits

  1. W

    what is the formula for calculating PSCC for final circuits?

    hi in college and watched some YouTube videos and read up on things I think I got the right formula but I'm not sure. Zsc= Zesc(or Zdbsc) + (R1+RN) (R1+RN) = milli ohms/metre x length x correction factor and then divide that by 1000 Zesc = Uo divided by PFC Then add together Zesc and (R1+RN)...
  2. UKMeterman

    Shower and cooker circuits shown as 2.5mm2 on shedule but overall condition satisfactory

    I am reviewing a EICR for a property I am buying. The vendor has had the EICR done, but both the Cooker and Shower are on 40A 60898 B curve mcbs and the cable type is shown as 2.5mm2 type A install methord C. I suspect a clerical error but as it is in the vendor document pack what would you...
  3. L

    I.R. testing existing circuits

    The accepted method of I.R. testing existing circuits has been to join L and N together and test to E, to protect against damaging any electronics that were inadvertently left in circuit. However ,with the increase of new types of circuits between L and E as a result of "intentional leakage"...
  4. O

    (UK) Adding additional circuits into old fuse box

    Hi all, First post here, hope I'm compliant with the rules! I did do a quick search before asking this, but I couldn't quite come up with the answer so I thought it best to ask! I'm currently going through and renovating some of my property, and the garage wiring is of some slight concern to...
  5. M

    How to map circuits when some breakers are quads

    I have a question about mapping circuits in a single family home. I recently had my panel upgraded to an Eaton 2040 panel, and the electrical contractor who did the work did not label things very clearly, so my plan is to relabel all circuits from scratch. As part of the upgrade he installed 4...
  6. J

    Rccb protection of lighting circuits

    My 1990 property does not have the lighting circuits protected by the Distribution Board RCCB.Only the power circuits are protected.If I get a trip from the RCCB the lights stay on. Do I need to upgrade my system to include RCCB for lighting?
  7. J

    Intrinsically safe circuits

    Quick question, I done my compex a while ago but I seem to remember the instructor saying that if a circuit is intrinsically safe, then the equipment does not need to be rated for a hazardous area. Does this seem right? Site I’m working on has IS circuits going to valve control heads that...
  8. R

    Flickering lights on separate circuits

    Evening All, Strange one so after a bit of advice. Got called to a customer this evening who had their boiler repaired after the circuit board got fried supposedly after a power cut when the supply was restored. They were told they needed a switch fused spur fitted as there was no way of...
  9. B

    Does a CU swap require a full initial verification on all circuits before it can be energised?

    To my understanding it would be ideal to test and inspect before energisation, but it isn't 100% necessary. If it leaves a client without power, it breaches health and safety (no power to safety services etc) or inconveniences them I'd have thought it would be reasonably practicable to turn on...
  10. S

    EICR Code for two circuits on one cable.

    Hi, Currently undertaking an EICR on a factory, we have came across an 4 core SWA and 4 Core SY which have been split in the DB to serve two separate circuits. The SWA has the Brown on a 10A MCB and the Grey is on a 16A. So clearly they have shared earths and shared neutrals, similar scenario...
  11. R

    Light bulbs in series vs parallel circuits in home.

    Hi, I had a question in my head that turned out to two and then BANG im confused. I need help with calculation here and explanation to get this right. If i want to build a lamp with 20 light bulbs in a 230V home. Each light bulb is 2watt. How much current will they take when they are in...
  12. L

    Overloading circuits

    Hello. I'm in the UK, and have some questions/concerns about my kitchen set up. So the fuse box has 4 breakers/circuits for the kitchen (the lighting is on a different circuit). One circuit covers the electric oven, gas hob ignition and a plinth heater. I then have a single 20A rated...
  13. T

    two SPD's in CU , one for zappi MCB and one for the rest of circuits.

    hi guys please help 1. i want to install zappi into existing CU with a type2 SPD should i also protect 32A MCB for zappi with an SPD? 2. i have CU(hager VML410AH) with type A RCCB incomer only is it ok to fit SPD onto it? thanks
  14. R

    Power Panel Changes Voltage with Branch Circuits

    I have a Single Phase Power box for a townhouse. When I read voltage across the Hot legs (A) and (B) to ground I get 123 volts with the main breaker turned off. With all the circuit breakers turned off and powering up the main breaker to the panel I still have 123 volts across both (A) and (B)...
  15. B

    RCD protection in industrial setting circuits

    Hi All Hope someone can help In industrial setting are all circuits required to be RCD protected ? Or is it just socket circuits ? Thanks in advance
  16. N

    25 ohms Zdb + same reading for all circuits

    Hi everyone, I have a particular job visited this morning, that on all circuits, at each point, i got a reading off around 25ohms for a earth fault loop impedance test(zs). I then thought to do the same at the DB for those circuits. Again, same reading was obtained. I then turned off the...
  17. O

    What's common practice with IR tests on lighting circuits?

    I had just installed a heat alarm on the downstairs lighting circuit during a kitchen rewire. The new kitchen ring / cooker circuit I tested IR for L-N and N-E at 500v, fine, but the DS lighting circuit consisted solely of 21 LED downlights, in various rooms and the alarm. All of which say do...
  18. S

    AFDDs for single-socket circuits

    Haven't been on here for a while, so sorry if this has been discussed before. BS7671 2018 + A2 Regulation 421.1.7 recommends AFDDs for "single-phase AC circuits supplying socket outlets..." (requires in certain premises). My intention is that from September 27th I will recommend them to...
  19. A

    7. 3 kw INDUCTION HOB

    Can I run a 7.3Kw induction hob off of 2 x 16 amp circuits single phase I'm not sure what size cable is installed, I will check. Would I be be able to run with the 2 x 16amp breakers or should I install a single 32 amp breaker with separate RCD? Thanks in anticipation.
  20. timhoward

    CPC common to 2 circuits...

    When I checked out this job I had a false sense of security from a recent competent looking EICR and two new CU's that looked to be fitted to a high standard. Most of the property does have a CPC on the lighting circuit, it's just this one room with a flat roof above that doesn't. This is where...

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