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  1. B

    Main rcd tripping

    Hello, my contactum b8003/2 30mA RCD feeds about 6 MCBs for light and power. Nothing had changed but suddenly my dishwasher seems to be the common denominator in tripping the main rcd. However, if I turn off all other MCBS, it doesn't trip. Please help me with my logic. This makes me think that...
  2. M

    Domestic Sub main earthing/CPC

    Hi all, Trying to get my head around an external install to a garden shed. I've run a 4mm H07 cable for the distribution circuit radial from the house. The 4mm is appropriate for VD over the distance. The cable is protected by RCD at the main consumer unit and a 20A MCB and travels up the...
  3. G

    Temp pole 100-amp disconnect to original 100-amp main panel wiring.

    Good morning, I'm hoping that a crusty retired construction super is welcome here. I'm remodeling a cabin that has the old 2-wire electrical system panel, so all the neutrals and grounds are attached at the same ground strip and the cabin service drop is 2-wire URD. I already updated all the...
  4. S

    Need to upgrade main panel?

    I have been meeting with solar system installers to install a grid-tied system at my house. Before I commit I want to verify whether I need to upgrade my main service panel. I have been reading about the 120% rule and am not sure if my current main service panel is sufficient. Any assistance...
  5. S

    Complicated dual tariff arrangement with four main switches.

    Hi Folks I'm used to (and understand reasonably well) simple dual tariff arrangements with two main switches (either two separate consumer units or a duplex). But I occasionally come across, and am now quoting for changing consumer units for a more complex arrangement that I don't full...
  6. alban moffitt

    Sub main Off a Sub main????

    i have been asked to run power to a timberframe outbuilding (6mtr x 10mtr). there is a garage cu which is a submain of the main cu, which would be easier and more practical to run the power from. i havent actually been to the site yet, but assuming suitable CSA feed to the garage cu, can i then...
  7. MrTapster

    Domestic Socket ring main causing flickering lamps

    Hi all To start off, there’s been no work on the ring main for 8 years or so. (Other than having a smart metre fitted about 12 months ago) Yesterday afternoon I noticed a buzzing from a plug socket. I unplugged what was plugged in thinking it was the appliance and didn’t think anything more of...
  8. C

    Commercial What Cert got fitting main switch

    Hi I have been asked to fit a main switch / isolator by my client as they have no means of isolating the full installation by a single means. So I'm planing on fitting a Wylex isolator like the ones meter people fit but my question is what Cert should I be I fill out at the end a minor works or...
  9. Steve93

    4mm cable into the bottom of main switch.

    Eicr today had a 4mm T+E connected into the bottom of a main switch which went to a separate dB with 1 20amp rcbo. Then swa to a hot tub. That part is fine. What I’m unsure about is the reg I can say that the cables are not ok in the bottom of the main switch. The other dB is only about a ft...
  10. B

    Rating of CU main switch

    Hi all, I noticed on my consumer unit that the main switch is rated for 100Amps, however the total load of all the MCBs is over 150Amps! I appreciate that diversity COULD (?) be applied in that not every circuit would be simultaneously running at full capacity, but is the installation...
  11. T

    Selecting a 3 or 4 pole main switch

    Evening all Pricing up a consumer unit change in a large industrial unit When it comes to selecting a 3Pole main switch for a 24 way distribution board, are there any factors that will change the decision between a 125A 3pole or 4pole main switch?
  12. D

    Altered ring main, now a DIFFERENT circuit is not working?

    I’ve just altered a ring main by taking 1 leg out of the board and taking it to a spur (then taking a leg back), to add a socket in. After doing so I’ve turned the board back on and everything is working as it should, other than cooker circuit (A radial feeding the cooker/hob, extractor fan and...
  13. S


    Installed a new radial circuit in a garage from an existing CHINT garage unit. All functioning well (tests fine) until after the RCD test. Then everything, lights etc stops working. On investigation, while I've got 244V at the incoming side of the main switch I'm getting a reading of...
  14. R

    does this count as a Main Linked Switch in a CU?

    does this count as a Main Linked Switch in a CU?
  15. T

    Correct Lock Off Device for 4 Pole Main Switch

    Hi all & thanks in advance for any feedback. Could anyone tell me the correct Lock off device used to safely isolate a 4 pole main switch? I'm not 100% sure if the isolation device with the prongs is the correct device to be used or if another lock off device is necessary. Pics attached...
  16. Strima

    Main Earthing Conductor Termination with SPDs

    Here's a question that I was asked earlier. If you have SPDs installed in a DB is it permissible to terminate the main earthing conductor into the SPD first then the DB earth bar? Or must it be terminated in the DB earth bar first then the SPD?
  17. Andy C

    Domestic TT earth, Dual RCD or RCBO and Main Switch

    I have a replacement consumer unit coming upon which is currently off a TT system with a nice low reading on the earth. There is no chance of the DNO converting to TNCS. No SPD or AFDD as per client. I intend fitting a new Dual RCD consumer unit. I have researched this site and there was talk...
  18. B

    200A or 250A main switch

    This switch, 250A or 200A? I’m saying 200A but go online and put that XT3N 250 and all it comes up is 250A?
  19. happyhippydad

    Understanding the new regulation regarding Main Bonding.

    Regulation 411.3.1.2 states .... Main bonding conductors shall connect to the main earthing terminal extraneous conductive parts. It then goes on to say... 'Metallic pipes entering the building having an insulating section at their point of entry need not be connected to the protective...
  20. Z

    Steel conduit used as CPC in flat, can’t find bonding, can’t find ring main CPC at C.U

    I’ve been asked to add a couple of extra points to the single ring main in a flat. Building fabric is concrete, all of the electrical installation is steel conduit buried in the concrete. I opened the consumer unit and could only see one CPC for a radial socket, as well as the main Earth. No...
  21. D

    New circuit to detached shed/garage in garden.

    Hello I am new to this forum and need a little help from an experienced spark to help me design a circuit to wire a detached garage (two sockets and ceiling lights) from a house ring main to 18th edition standards. This will be notifiable so everything has to be pukka. Cable can be in steel...
  22. M

    Domestic LED striplights wired to ring main

    Hello all, I'm new here, first post and no elec qualifications, so a few condescending replies I'm sure are more than deserved. I'm currently looking to add some strip lighting to the back of some shelves in the bathroom (wife thinks it looks fancy). What I really want to do is avoid a second...
  23. C

    Neutral - Earth link in Main Switchboard

    When is an earth neutral link required in an main switchboard? Is it particular to the earthing system? Is it common to earth the source neutral at the first point in the LV system where the neutral is terminated - the main LV switchboard. If the Neutral terminal of the transformer is...
  24. 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...
  25. S

    Main Protective Bonding Conductor question

    Hi guys Would appreciate your comments on the following.. I am currently involved in the refurbishment of a building with 2 service heads (both in use) but only one gas intake and one water intake. What are the main bonding requirements in this situation? I am assuming both MET's require a...
  26. Y

    Main rcd tripping even though its 100 ma

    Hi There's a workshop outside the main building with a couple of sockets protected by a 30ma rcd. Even though the rcd inside the main fuse box is 100ma the 100 ma rcd trips without the 30ma not tripping. Changed 30ma rcd still same. How can I get the rcd in the workshop to trip without tripping...
  27. D

    rcd tripping on a ring main

    Ok help before a pull out the rest of my hair got an rcd that trips when ring main breaker turned on got continuity but still trips when only live connected ant ideas
  28. C

    Main Earth Bonding (two supplies)

    Large house with x2 power supplies/ service heads. first supply 3 phase TN-S located in a pig of a place and is furthest away from the gas and water entry points and meter positions. Second supply is a single phase TN-S located only a few meters away from the water and gas entry points to the...
  29. V

    ring circuit for a submain?

    trying to find answers in the reg book, but is there anything to say you can't install say a larger ring circuit for a sub main? to reduce volt drop / cable size etc. Normally you would obviously install a large enough cable, but would this be acceptable , whats our thoughts?
  30. K

    OK to spur lights from ring main?

    Hi, I want to add wall lights to a room, but don't have access to the floor above, so can't easily access the lighting circuit. There is a power socket on the wall where I want the wall lights. Is it permissible to take a fused spur from the ring main for the wall lights? Regards, Glenn
  31. D

    Trainee Single Pole Fused Spur From Ring Main

    I have two cables for wall lamps (1mm T+E) going to one of the socket in the back of the TV. These lamps will be controlled with smart bulbs with a little remote control or/and an app on the phone, no need of wall switch. I'm considering to use the 47mm double metal box to host a modular single...
  32. happyhippydad

    Does this require Main Bonding?

    The water pipes enter the house in metal, then there are a few cm's of copper after the stop cock and then plastic. It is hidden behind the kitchen draws (which can be removed to access). Does this require Main Bonding? The stop cock tests as 0.36Ω to earth, it is TNCS. I just cant see how...
  33. Alrebcon180

    Main 185mm earthing query

    Hi guys bit of knowledge needed.. Have a 2x185mm 3phase supply going to a panel board with 800amp main switch from a UK Power networks transformer about 15m away, also run with them a 185mm earth which goes to a earth bar next to the panel board where all the outgoing swa earth overlays are...
  34. T

    Main earthing Conductor also bonds water

    Domestic TNCS, main earthing conductor runs to water pipe, bonds via clamp with label, cable is continuous, then runs on to MET in DB. Seems wrong, but cant find specific reg to say so....any thoughts? Thanks, Timotei
  35. R

    Main fuse keeps burning

    Hi we are currently located in Nairobi, Kenya and have UK 240V. We have a problem that the fuse in the main fuse box keeps burning. Each time we replace the fuse it lasts roughly a month. We have seen that the burning to the wire is on the inlet side of the fuse. The house doesn’t have many...
  36. C

    Electrician 3 phase RCD main switch on Dis board

    Hi guys My friends are selling a house in France and they had an electrical survey which said they need to fit a RCD main switch on the dis board, the supplier has fitted an RCD at the main in coming cables but it’s about 20 yards away from the house and the survey said the dis board must be...
  37. G

    Loft conversion sub main & diversity

    Hi all, I am currently having a loft conversion completed and want to put in its own board in the loft. The main reason for this is if in the future, I want to let it out as a self contained unit, it will be much easier. The conversion will initially have a ring main 32 amp and a lighting...
  38. M

    Domestic Unidentifed Cables from Main Supply

    I have recently moved into a new house and had to reset the breaker after a bulb went. When I was crawling around with a torch, I noticed some cables (Red, Black, and Blue-ish/Green-ish) leaving the main supply and running into the wall without going through the meter or the consumer unit. Is...
  39. D

    Domestic Mapping existing ring main

    Hi, I am a first time DIY poster - hoping to navigate the tricky line between getting a bit of a steer in the right direction and not requesting step by step instruction. I am hoping to DIY the electrics on my extension, and in advance of the project I am trying to map the order of outlets on...
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