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  1. 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...
  2. 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...
  3. 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...
  4. 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...
  5. S

    Insulation resistance testing

    456megaohms on a 25m 3core swa is acceptable as its more than 1megaohms. Correct.
  6. 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...
  7. 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...
  8. 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?
  9. 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...
  10. 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...
  11. 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...
  12. 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.
  13. 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...
  14. 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...
  15. 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...
  16. 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
  17. 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...
  18. 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.
  19. 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
  20. 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...
  21. 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...
  22. 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?
  23. 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...
  24. 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 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...
  25. 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...
  26. A

    replacing pmmc unit of waco 2.5kv insulation tester

    How can I do it? Where can I find PMMC coils?
  27. 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...
  28. 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...
  29. haptism

    Insulation properties of heat shrink, and tape

    Have question thats been on my mind for a while. Does anyone know if; at 250 -500 v, a single layer of heat shrink, or a single layer of insulation tape for that matter, covering a bare conductor, sufficient insulation against ?? direct contact/a shock ? It seems a bit thin in comparison to to...
  30. joel89

    Fluke 1507 Insulation Tester

    in a used condition, used about 5 times in total no longer needed as I have an MFT. Paid £450 about 2 years ago! Comes with carry case, croc clips, leads, user manual. I will post via tracked courier I think its around £9 tracked. Offers please
  31. TonyJohnson

    Isolation transformer and insulation monitoring device in horse box/bar

    The regs state 717.413 a Isolation transformer and insulation monitoring device should be used. Are there any guidance notes on type or makes i should be looking for. I see you can get 230V primary 230V secondary boxes but i'm also not sure on which to get in terms of load.. I'm inspecting this...
  32. kkkkk

    Fibreglass insulation safety

    Hi guys What do people find is the best protection against horrible fibreglass insulation - I always seem to be left coughing and itching!!!? I do wear safety gear, but nothing seems to be 100%. :)
  33. F

    (DIY) Extending the ring up the wall (insulation?)

    So, I'm now on my second electrical project (after the success of adding a double socket to mums attic!). In my "computer room" I'm using two extension leads to power 7 or 8 plugs, all from one single socket in the room. One of these plugs is for a powerful PC, the rest are for low power...
  34. N

    Insulation resistance - strange readings

    Im getting some strange reading on a new circuit(ring main) ive installed and i was wondering if anyone else had experienced the following. insulation resistance at 500v on L-N is >500mQ (which is fine) then insulation resistance between N-E starts at 400 then climbs to 500mQ then insulation...
  35. T

    Insulation over LED downlights

    Sorry if this has been asked before - couldn't find anything using the search function. After fitting LED downlights, can they be covered with loft insulation or will that cause a fire risk?
  36. S

    NO switch insulation resistance failure

    How often do we usually have insulation resistance failures on an NO switches leading to unexpected starts?
  37. gazdkw82

    Single brick wall insulation options

    We have a small toilet downstairs that had signs of mould. I've decided to pull the plaster off. I'm glad I did because it was slightly damp in places. I think this is mainly because 1. It's a single brick room and 2. They just nailed the plasterboard to the brick leaving a gap of round 10 mm...
  38. J

    Failed insulation on Fan

    hi guys, Could someone please tell me why the ‘insulation’ has failed on this pat test please? I thought over 1MOhm was ok? The test is on a fan in a dental surgery. Thanks
  39. B

    3 Phase Insulation Resistance Test on motor & TP & N skt help

    Looking for some advice on how to carry out a IR test on a 3-phase motor and a TP & N skt, these are parts of a module I have failed on a test and am looking to see where I am going wrong and what the normal procedure for carrying out this test would be?
  40. R

    Downlights and Loft Insulation

    I have these downlights installed under loft insulation with halogen GU10s. They are marked as fire rated and fire rated under insulation, but the installation just doesn’t look safe? I’m wondering if i should convert them to LED bulbs (that's happening progressively as the halogens blow anyway)...
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