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  1. T

    Main RCD Tripping & Not MCB

    DIY expert tried changing his own Consumer unit from an old 3036 re-wireable CU to a 18th Edition (100A main switch / 63A 30mA RCD / 7x MCBs) I was called out because he couldn't get his sockets (ring main) back on - NEITHER CAN I, I HAVE TRIED EVERYTHING I THINK... The Lines are terminated...
  2. B

    UK Oven trip MCB

    Hi all, I’m hoping someone will be able to give me some advice on my oven. Tonight I had both ovens on (as has been done on several occasions). When I went into the kitchen about 10 minutes later I noticed the oven was off and had tripped the 32Amp MCB. I reset it at the CU and it came back on...
  3. B

    UK RCD vs MCB trip

    Evening everybody, I’m wondering if someone wouldn’t mind answering a question for me about RCDs. I had a water pipe burst behind my washing machine this evening, and once I’d isolated the leak I noticed the sockets had tripped. When I went to reset the breaker, I noticed that it was the RCD...
  4. J

    RCD vs MCB...

    Does an MCB protect against fault current in the same way as an RCD does? As in, both devices trip by way of detecting imbalance in the Line conductors and thus using magnetism to sprag the switch? I ask, because if so, I can’t get my head round why an RCD is better than an MCB. I know that it...
  5. L

    No end to end 2 Radials on one MCB

    Hello, I have tried to search the forum but have not found anything although this must have been asked a thousand times. When completing a board change for example and there is no end to end on the neutral does downgrading the mcb to a 20amp and effectively running two radials from the same MCB...
  6. N

    Tripping mcb and rccb

    Hi guys. Just want some advice or thoughts from the pro's. So I'm an engineer who works on espresso machines. Going back a few months ago now I got called out to a machine tripping the power, in my line of work this generally means one loop on the heating element has shorted to ground or one...
  7. N

    Why would spike lights trip an MCB as if a dead short is present ?

    Just finished installing 20 x spike lights in a customers front garden. 2.5mm SWA ran from existing junction box feeding existing fence lights. All pulling no where near 1A in total. When all connected and wiring tested, went to switch on MCB and it popped. Rendering the MCB useless as if L-N...
  8. J

    Looking for electrician to swap MCB in OL10 area.

    Hi. Im looking for electrician to swap mcb in my consumer unit for one suitable for single phase welder with max input current of 16A. In my consumer unit there is 32A type B mcb that was used with electric shower that is disconnected. I need it swapped for 16A type C (been told its a right...
  9. Z

    MCB trips ONLY when open in one go all lights together

    I have about 50 led spot lights + more light , all together is about 400w if I open them all in one go together, then the MCB [=6 am] trips immediately, but if I open them one by one I have no problems at all ! I tried to replace the MCB with another 6am and it did the same, but when i replace...
  10. buzzlightyear

    need max for old mcb

    any body got the max ohms for old dorma smith mcbs , I asked dorma smith years ago sent me max ohms for old load masters .
  11. F

    Industrial C50 MCB

    Does anyone know where I can get an old Crabtree C50 type MCB from?
  12. M

    Intermittent mcb trip electric gate

    Hi, just registered, I qualified in 1973 and and not done much electical work for the past 30 odd years but I obviously have grasp of the theory. I have an intermittent mcb tripping on my electric gate, which I installed. (All electric no hydraulics) The mcb will trip in any weather...
  13. N

    6mm T&E on 40 amp mcb

    while doing EICRs i often find this combination, if its clipped direct it dont worry me however many times i have no idea how the cable is routed im just wondering how others would code this?
  14. K

    Need a different mcb

    Hi al it’s not. DIY job I’m aware of that. But I have just purchased an electric range cooker. Had an electrician out to extend cooker cable and he told me the instructions Manila of the cooker required a 40amp MCB. I’m not really in the market as of yet to be changing the consumer unit and I...
  15. Ashley-Joseph

    Spur from 32MCB

    Just wondering if I got this right but is it ok to take a 2.5mm spur from a 32MCB ring main Or should I use 4mm cable.
  16. coolsparx

    Old Crabtree Starbeaker MCB Compatibility

    Does anyone know if the current Crabtree 61/B32 Starbreaker 32A SP 6kA Type B MCB will fit the old board pictured?
  17. J

    Wylex Stotz PSB 63A MCB

    Does anybody know where I can source an old style Wylex PSB 63A SP MCB? It's to fit an existing 3 Phase Distribution Board with fork style busbar. Thanks in advance.
  18. A

    Domestic Oven won’t work...unsure issue.

    Hello, My cooker (LOGIK LFTC60W16 oven with grill and 4 hobs had it maybe just over 2 years) stopped working about 2 weeks ago. I found out we have no cooker switch on the kitchen wall so checked the Circuit Breaker box. Everything was on. With no other option I left the cooker MCB switch in the...
  19. The Flyinhos

    Cheap MCB lockout devices

    Had these arrive today, thought it was quite a bargain. 10x lockouts for £9.00 including VAT and delivery. Thought they maybe cheap n nasty, but pleasantly surprised. Can't knock em for the money. https://www.amazon.co.uk/dp/B07FDZNTG2?ref_=pe_3187911_264767211_E_301_dt_1
  20. W

    Body’s resistance with mcb only

    If there’s 230v and the body’s resistance is high .. Meaning the current will be very low but enough to kill you. Can we get electrocuted without having a 30ma rcd to stop this as the 6amp breaker will not have tripped ?
  21. Marcus Vaughan

    Type C MCB needed for EV Charging?

    Hi all, I've not a lot of experience with EV but was called to a local job to investigate a loss of power to a 32amp 7.2KW EV charger. It turned out the 32A MCB (Type B) had failed, and would not even operate when completely removed from the board. I happened to have a matching Contactum B32...
  22. T

    Lock Off Device for Triple Pole Main switch & MCB

    Hi all. I am undertaking an assessment next week called SAFE ISOLATION OF SUPPLIES. It involves isolating and securely locking off a circuit to be worked on. The 4 items to be isolated is THE WHOLE INSTALLATION, A 3 PHASE CIRCUIT, SINGLE PHASE CIRCUIT & LOCAL ISOLATION (which is an isolator...
  23. T

    Domestic Type of MCB .........................

    In domestic when the Zs easily low enough why do we default to have type B instead of C curve MCB's/RCBO's
  24. R

    Sub panel: Underrated MCB?

    Hello all A quick question about an existing layout if I may. The layout consists of a main CU connected to a sub panel via a single 63 amp MCB. A Dorman Smith K1PC63 to be exact. Total potential load on the sub panel is 25Kw. Routinely all of that load is present on the sub panel...
  25. C

    Max zs on double pole mcb

    I am filling out test sheets and have a merlin gerin D32 C60 HD double.pole mcb. The rating on the mcb says 415V feeding 2 feeds to a canalis busbar. BS7671 States max zs for D32 0.4 secs is 0.34. Is this just for single pole MCB? I have also check my max zs value from manufacture stating...
  26. C

    Appliance tripped MCB after....

    Carried out an eicr and noticed x2 double sockets have reverse polarity that supply a frying machine at high level. (this was a return visit to correct the faults) After correcting the reverse polarity on the two sockets i plugged the fryer back in and the circuit MCB tripped out and the...
  27. R

    mcb and cable size help

    Hello all I've just developed a wiring fault on the only ring main, after spending a few days attempting to find it and being pretty appalled by my findings. I have decided to re-wire the house. I have just spent all my spare money on a cruise so I guess I will have to get "Me sen ltd" to do...
  28. M

    Domestic New Oven tripping mcb massively

    Hi everyone, stumbled across your forum while googling tonight, hoping for a bit of advice... I have some electrical knowledge, and I fit/change electric meters for a living for past 20yrs for one of the big six! Have been given a brand new (but faulty) oven by a relative, an Electrolux...
  29. V

    Domestic Shower tripping mcb after being used

    Hello. Can anybody please help. I've been in my house for 5 years and had no trouble with shower at all. A couple of weeks ago the wife says that shower wasn't working. I looked at circuit board and mcb had tripped. Flicked switch back on and everything was ok. Went for a shower later and its...
  30. J

    Living Room MCB breaker tripping

    Hi, The breaker for my living room has been tripping since Sunday. I have physically checked all the wiring in the sockets and they all seemed fine. I then checked them all with a socket tester and the read was fine. I have used all of the appliances on a different circuit and they are all...
  31. B

    Ground floor lighting trips out mcb

    Hi everyone, My first post but straight in with a couple of issues. I'll start with a 6amp MCB that keeps tripping out relating to ground floor lights. For your info: There is 10 x 3w led recessed lights in Kitchen, 8 x 3w led recessed lights ,plus a main central Led light (approx 100watt...
  32. S

    Lighting MCB keeps tripping

    Hi all. Just after a bit of advice. Just got home on Christmas Eve, went to put the lights on as you do, then there was a "pop" from the MCB. Usually when this happens one of the halogen bulbs in the bathroom has gone and needs replacing. Usually resetting the MCB, identifying the blown bulb...
  33. D

    Domestic 8.5kw shower on a 32amp mcb

    Hello All Can any one provide non sarcastic suggestions as to why an 8.5kw shower has not tripped the 32amp mcb protecting that circuit? Found this install in a domestic property. It seems to have been there for years, without out issue. Thanks DD
  34. Spark40

    Domestic Schneider Electric Acti 9 iC60L MCB Mini Circuit Breaker 4P, 40 A, 10 kA, Curve C

    i have being using my multometer 4023 model on my mcb and its reading 309.3A but to my calculations it should be below 4 amperos can anyone lend me a 320A fuse would be delightful
  35. DRM

    Spotlights tripping MCB when switched on

    Hello, my mate’s asked me to look at his spotlights in the kitchen because they were temperamental for a few months going off for hours at a time then coming back on and now they just trip the MCB as soon as switched on. They’re 12v spots. They were on a dimmer switch so I changed that first to...
  36. M

    Mcb trips but tests clear

    Evening all Let’s see if anyone can solve this one. Recently wired a new extension. Today connected up ring circuit to 32amp mcb, all relevant dead testing done ir +999mohms and ring continuity.28 .28 .48. So all good turn mcb on and pop it trips off. Rechecked testing removed sockets just to...
  37. LewisM

    6A MCB Tripping on Earth Fault Loop Impedance Test

    Hi, just finished a partial rewire at my sisters house and when testing the two lighting circuits (up&down) the 6AMCB trips for both circuits individually, I thought the MCBs might just be sensitive to the test but the smoke alarm circuit also 6A is fine when testing, R1+R2 and IR test all fine...
  38. Marcus Vaughan

    Square D MCB to RCBO

    Hi All, I have just been to to view a job on my way home. The customer is asking for a new double socket immediately below the consumer unit (that's convenient!). It's an old Square D board without an RCD in sight. I guess it would be very easy to install an RCD socket outlet - spurring from...
  39. B

    MCB rating advice is appreciated.

    Just a quick question got a new boiler going in soon and noticed that the MCB that will be used for the dedicated feed ( on kitchen ring ATM ) is 16amp is this correct rated MCB? or does this need replacing with a 6amp MCB with a 3amp fuse at spurr? Cheers
  40. S

    Two 'Circuits' in one MCB

    Can't find the recent thread about this, but I've been looking at smoke detectors and got this from AICO under System Installation: "• The supply for the mains powered alarms shall be taken from an electrically protected, regularly used local lighting circuit at the nearest source except for...
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