sub main

sub main

  1. Yellowhammer

    Extending sub main

    Hello, Planning some work for someone currently installing a new CU and a switch fuse in an extension, fed from a new DNO supply. Have turned up and had a look at it, mostly seems all okay other than the hockey stick being on the wrong side of the meter box. However, the 63A switch fuse is...
  2. cliffed

    comply to Regs to install a MCB for the Sub Main to the 1st Floor DB

    Replacing DB’s with all singing all dancing RCBO’s Problem’s we have now…Existing installation consisted of DB Grd Floor.. DB 1st Floor…Grd Floor DB supplies 1st Floor DB…16mm T&E installed IN fabric of building. DB 1st Floor supplies Remote Garage Block 16mm T&E With the Sub Main to DB 1st...
  3. N

    SUB MAIN QUESTIONS. ADVICE NEEDED

    Hi all. I have been asked to take over a job an electrician has started, and has moved abroad. The house is a big mansion, with a 3PH supply, with 100A fuse on each Phase. The electrician has ran 2 25mm 3core armours to another 2 DB’s in the mansion, and there has to be a DB fitted where the...
  4. Yellowhammer

    Garage sub main on existing TT install

    Hi there, long time lurker, first time poster here. Straight down to it.. A friend asked me to add some sockets and additional lights to a small outside office they have tacked onto the side of their attached garage, no problem I thought, apparently the garage already has a DB in it with radial...
  5. V

    PV installation - dedicated circuit, or from sub main board? MCS query

    hi thank you for help in advance have a potential pv installation for a garage roof that is some 60m from the main house (main incomer in the house). Spoke to a napit/mcs worker - he said the pv installation has to be on a dedicated circuit. My interpretation is that a dedicated circuit on the...
  6. I

    New SPD Regs for Sub Main

    Now that SPD's must be fitted regardless, how does this stand from a sub-main perspective? Went to look at a job and they want a supply to a pre wired Shepherds hut 50M away with no SPD as it has been sat unconnected for a couple of years. The main incoming is entering an old barn that has a...
  7. D

    Sub main supplying new build

    Good morning all, long time reader first time post so looking for some help I’m qualified as an electrician but haven’t worked as a sparky for 15 years or so. I’m just starting a self build and going to do as much as I can but over thinking that the first hurdle New main in to the house was...
  8. T

    Up front RCD tripping with sub main connected.

    Hello all I have recently installed a sub main in 4mm 3-core SWA, approx length 45 metres, to feed a small garden office. Final circuits in the cabin are protected by 30mA RCBOs and the supply is fed from a 32A MCB on the non-RCD side of the DB in the house. As the installation is TT I put in...
  9. Viper22mike

    UK Sub main joining niceic advise Needed

    Joining niceic and doing a sub main to a garage off a tns earthing arrangement using 6mm Swa. The question is I have 25mm tails on 100a main fuse to a down rated dp isolator with a 63a fuse from there the swa. I'm filling in the eic for them to view do I put the 100a or 63a main fuse size in and...
  10. J

    Sub Main Connection From Meter Box

    Hello All, new to the forum. Would be grateful for advice on whether the following proposal is an acceptable solution or open to any suggestions for improving. The brief is to supply a detached garage with incoming power and CU. Power will be used to supply a couple of sockets, lights and an EV...
  11. SparkyKris88

    Running Parallel Cables for 400A Sub Main

    Hi All, I’m after some advice. I’ll cut to the chase but I can give more detail if needed. A 400A sub main supply needs to be ran 100m, a pretty direct route on ladder tray. Instead of one large cable (I think it’s 240mm), I was looking into running parallel cables instead. I’ve not done this...
  12. P

    sub main to consumer unit on new builds

    Hi. I have a small new build sit to price up. The consumer units are to be sited in the middle of the house behind the front door. After best way to supply from external meter box. I was thinking of using split concentric from kmf with a metal plate over it on internal walls. surface mounting or...
  13. T

    SWA Sub Main advice/comments

    Hi all, looking for a bit of advice and confirmation on my proposed plans for a SWA sub main to a ISO metal storage container. I've calculated the max demand in the ISO will be about 20A (300w of led lighting and 2 double sockets for chargers etc) It will be fed from a 3ph DB in another...
  14. Z

    Sub main in a domestic property

    Hello all. I have visited a domestic property with two consumer units, one downstairs and then a separate one for upstairs. The upstairs is fed by a 16mm twin and earth and the downstairs is fed by 25mm tails. The cu downstairs is a duel RCD. The question I want to ask is, since the cable...
  15. buzzlightyear

    SUB MAIN IN FLATS

    been out to test a 1st floor flat and all the sub mains and meters are in a hall way ground floor going to each flats which are 5, the sub mains are not rcd protected ,i guess when it was converted and tested to the 16th or there about . can not see how it was installed so the building...
  16. D

    Sub Main Zdb Test

    Hi, this is my first post here. I have a 3 phase board with a 40amp circuit breaker supplying a single phase board to a small office. I understand that with the 3 phase board how to get the Ze thats not an issue. How do I test to get my Zs (Zdb) for the single phase board? Do I link the L&E...
  17. J

    Zs for a CU with sub main and fused isolator

    Setup: Consumer unit fed via sub main from a 60A fused isolator switch. This is connected to the service head MET via a 2m earth connection. How would one go about both calculating and documenting the Zs? Would you be treating the fused isolator switch as it’s own db and therefore be...
  18. B

    Sub main 125m in16mm with 80A 1361 over current device

    Just been to a new build with a 125m sub main as per tittle, owner says the sparky workout the cable size, I wonder how!
  19. J

    UK Sub Main Armouring Earthing Question Combined CPC and Main Bond

    Hi I have reviewed a few posts around this subject, but my question is not covered. I know that the Submain Earth has to be sized on the DNO incomer, not on the submain to the external building itself. My question is if I need two main bonds in the submain building, for example one for ground...
  20. J

    UK Installing a sub main from existing TT system

    Hi all, I’m new here and after some advice on a sub main circuit I have a 3 core SWA feeding a log cabin from a house. The house has an existing TT system and I’m just wondering what the best way to supply the log cabin would be? What would I need up front to protect the SWA, I’m presuming a...

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