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  1. T

    UK Cable under exterior insulation

    Hi, diyer here, only for laying cable!!! Before the builders arrive to clad my house with exterior insulation and rough cast I plan to attach a 1.5mm armoured cable to the house to future proof for a security/floodlight. The cable will run approx. 7m before entering through an old vent. Is this...
  2. E

    Insulation resistance check on LED fittings

    Hi, Do I need to disconnect LED fluorescent fittings when doing an insulation resistance check? Thanks
  3. H

    Reference method for the old sheathed single core cables run in attic spaces with insulation

    Good morning I am just wondering what reference method is suitable for the old single core sheathed cables if they at some point enter an attic space under insulation.ive had a read through the regs book but still unsure Cheers for any responses Harry
  4. A

    UK Is this wiring in the attic with insulation okay?

    Hi, I have a guy working in my attic. I have been getting bad vibes off him for the last few days and things that are starting to raise red flags. So, I went into the attic to just have a quick look at what he is doing. (I have zero experience with electrical installation but what I saw looked...
  5. M

    What are the implications of a failed Neutral - Earth insulation resistance test?

    Greetings! Newbie here! We have 3 phase installation in our Lighting dimmer rack. During Insulation Resistance testing on Earth-Nuetral, readings was 0.33Mohm on 500v test. What causede the failed test and how can I troubleshoot? Thank you! Markus
  6. B

    Insulation Resistance Calculation

    Hi, I have an engineer who is completing his 2391-52 exam tonight and he has been told one of his mock questions was wrong, I have completed the working out myself and came up with the same answer as him, so either the paper is wrong or something has literally left my mind!! "Determine the...
  7. D

    UK DIY - Install Cat6 through rigid insulation glued to Drywall

    I'm looking to data points for Cat6 in a couple rooms through out my house. Plan is Patch Panel, though brushed panel, through eaves, terminating in a gang faceplate. I've got easy access to eaves so getting the cables from one wall to another should be easy enough. The walls are...
  8. G

    Insulation Resistance Testing

    Should I remove all the loads when testing between live and neutral?
  9. D

    Internal floor sound insulation and cable derating

    I'm looking at adding 100mm of sound insulation in an internal floor with 9x2" joists. The house has been rewired at some point so there are cables running unclipped in the void of the floor. Most of these are 2.5mm for the sockets, and also some for light fittings. Plastic radiator pipes are...
  10. H

    Insulation resistance with vulnerable equipment unable to be removed

    Good evening Was wondering when testing for.insulation resistance and there is vulnerable equipment in circuit but unable to disconnect, I understand that you combine the line and neutral conductors and test to earth. I am just wondering if it's ok and safe to do this at 500v as there is no...
  11. S

    Insulation LN Test Fail through cooker isolator

    As it says really. When testing LE or NE resistance > 300M ohms but between L and N I was getting a reading of about 0.2M ohms. Could it be the BG cooker switch that has two neon lights that is the problem? If it is, after shoving 500V dc through them, should I replace this erstwhile brand new...
  12. happyhippydad

    Any recommendations for shallow, fire rated, insulation coverable, integrated downlights

    As in the title. I need downlights that can be covered in insulation, fire rated and integrated. Preferably quite shallow as well! I'm struggling a bit to meet all the above criteria :(. Cheers guys.
  13. S

    Panel Lights in insulation...

    Does anyone know about how much of a void in insulation is required for lights like these? Putting downlights in a loft conversion and if I install standard size ones I'll be creating some serious cold spots...
  14. B

    Conductor insulation breakdown

    I’m currently problem solving a lighting circuit issue on a retail park. newish install (12months old) IR of 12M Ohms across all three conductors, getting some very odd IR readings overall, I got a low reading between two separate disconnected cables, sent my meter off to be calibrated and came...
  15. KeenPensioner

    Insulation resistance with broken line conductor

    Hi, I'm not an electrician but I'm studying the material required for the C&G 2394/5 just for the sake of it. I think I understand the theory behind insulation resistance testing (but maybe not!) and the reason the test is performed at 500V (insulation condition, fault finding) and that loads...
  16. W

    Insulating around cables

    I need to insulate under my suspended floor which has many cables running through the joists (consumer unit is below floor). My main concern is causing the cables to overheat etc. Here's a quick overview: Joist height: 140mm Cables: Mixture of circuits but the 2.5mm 32A rings are my main concern...
  17. S

    Insulation resistance testing

    456megaohms on a 25m 3core swa is acceptable as its more than 1megaohms. Correct.
  18. happyhippydad

    Global Insulation resistance <1MΩ but individual circuits are all > 1MΩ

    With regards the title is the reason for this because the circuits are all in parallel? I am talking in relation to a L/N - E test. If Rt = global resistance for whole CU and R1, R2, R3 = L/N - E resistance for each circuit then am I right with the following: 1/Rt = 1/R1 + 1/R2 + 1/R3 So...
  19. P

    Low N/E insulation resistance

    Hi all, Just installed a brand new radial circuit for the upstairs sockets with Prysmian 2.5mm T+E, around 21 metres in length. When testing the insulation resistance of the circuit upon connection to the consumer unit, I seem to repeatedly get around 49 Megohms when measuring Neutral to Earth...
  20. S

    Quinetic controller ok with 500v insulation resistance test?

    Hello Everyone Hopefully the title is self explanatory. Or should I disconnect it for the test?
  21. A

    Loft insulation and ratings

    Hi guys New build small 2 bed bungalow to have 300mm of insulation in loft space. Obviously all circuits to be ran in loft and dropped. Circuits to be used are alarm circuit 6amp, lighting 25x 4w downlights 6amp, 2 x 32amp ring mains, 16amp boiler radial, 32 amp hob/oven circuit (undecided if...
  22. R

    Insulation resistance check

    Hi - I have a Warm-up underfloor heating system. And it's stopped working. I did a basic resistance check - and clearly there's a problem (shows just 18ohms when it should be nearer 200). Warmup have said they can send an engineer around to lift a tile after doing a thermo heat check...
  23. G

    Insulation on swa in a board

    Hi gents Whilst I am qualified as an electrician I am a maintenance engineer so don't do much installation work hence seeking advice here. I recently installed a new 3ph distribution board for a new machine. As I don't have my testing and inspection ticket another person did the minor works for...
  24. C

    Thermal insulation covering cable

    I'm doing a garage conversion. 70mm insulation on block then an inch gap battened on top, then 35mm insulating board. Where's best for the cable to go in terms of derating etc... Cheers.
  25. Sean Kennedy

    New Build regs on insulation

    Hi Has anyone had any experience regarding insulation in walls on new builds as to what size mcb they are using for ring main circuits. I have checked the regs and seen that 100mm > insulation derates the cable capacity a fair bit. The builders are using 140 mm in the walls. I have pointed this...
  26. E

    Insulation Resistance Results

    Hi, I’d like some clarification with regards to insulation resistance results I’ve got. Carrying out initial verification on a new ring final circuit. New cable, 9 new MK double sockets. r1 - 0.43 rn - 0.42 r2 - 0.68 R1+R2 - 0.28. Carried out insulation resistance test: L-N - >2000 MOhms L-E...
  27. HoverSPRX

    "Clever" client derated the cables!

    So I'm currently sorting a CU change and kitchen rewire while also fixings some bodges by a have a go client, came back this week to discover that he has decided to insulate the void between ground and first without mentioning it. Now this has derated all his cables by half as they are tottaly...
  28. Tom Crabbe


    Hello, has anyone noticed in the new GN3 that any reading below 20 Mohms now has to be investigated or is this a printing mistake as it used to be 2Mohms? Thank you Tom
  29. Bobby34

    Insulation Resistance testing method

    Good afternoon, apologies if this has been covered before i've not long joined so gradually finding my way around. I have my Part P assessment coming up on a new installation and would like to hear some opinions on how people carry out their IR tests. In guidance note 3 it gives an example of...
  30. L

    Basic insulation _________

    Is twin and earth classed as double insulated? If it is, is it necessary to use when you using ADOS when the regs say basic protection can be provided by basic insulation.
  31. L

    Trainee Basic insulation _______

    Is double insulation cable necessary such as twin and earth if under automatic disconnection of supply it states that basic protection can be achieved by basic insulation only. Thanks
  32. J

    Insulation Resistance...

    I am just working through my understanding of the insulation resistance test, and I want to find out the best way to do the combined Live-Earth test where the Line and Neutral conductors are connected (joined, or however it is best described) through one probe of the tester, and the other probe...
  33. D

    Domestic Bathroom downlight insulation coverable + exisiting CPC cut

    Pleased to find this forum, my 1st post! I will get an electrician in for this to make sure it's safe and tested but I want to understand what's right before getting a quote/posting a job. Previous owners had downlights installed in the bathroom but a later test certificate identified the CPCs...
  34. Adam_92

    Insulation restistance on heating system

    Hi, I do not work on a lot of heating systems but when doing an insulation restistance test on a S plan heating system do you only remove the digital programmer?
  35. N

    insulation resistance test on shower circuit with neon isolater

    On a new install of a shower circuit, with a neon isolater, is it better to use choc blocks to bypass neon isolater or would it be ok to just test live-earth (live being neutral and live combined) and miss the live-live test? If testing just live-earth, would you write it down in details of...
  36. B

    Is there really no right way to work with down lights and insulation?

    Hi All, I'm kind of hoping to get confidence in my decision to have spots fitted into the ceiling of our new extension, but keep coming across different advice...help would be welcome! We're looking to fit 12 LED spots (Aurora Pro 6w) into a lean-to pitched roof, split into two circuits on...
  37. naylorpd

    Insulation resistance test issue

    Back in 2013 I had a Domestic Electrical Installation Condition Report done on my rented property - nothing horribly major but one thing I didn't understand... I had a C3 code for "0 ohms readings for I.R test for sockets & lighting (unable to remove all loads sockets, lighting had electronic...
  38. A

    replacing pmmc unit of waco 2.5kv insulation tester

    How can I do it? Where can I find PMMC coils?
  39. haptism

    Low insulation reading

    Testing a ring earlier and found 0.8M ohm at 250v between (L&N) - E. This wouldnt be a neon causing this would it as im testing between L N (joined) to E ? I have not yet tested between the three individually. This low reading is making me hope somethings still connected, there is a digital...
  40. T

    How to bypass an RCD and carry out an insulation resistance test on a circuit

    Hi all. I'm a 4th year electrician currently awaiting to finish my trade test. (FICA in Scotland) the only parts I have to pass is the testing part and fault finding. I'm currently studying testing as this is something I have done the minimum of onsite. Could someone tell me how I would...
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