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  1. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    Morning all,


    I am looking to install a secondary consumer unit in my garage, linking from my existing house consumer unit.


    The first question is If it is ok to run 16mm2 Twin and earth SWA through my hallway and lounge concrete floor in order to get to the garage or should I be running it through the walls? I intend to run a 60A supply to the garage. I could run conduit in the concrete floor?


    Secondly, would it suffice to add a 60A rated RCD to the existing house consumer unit for the SWA to run to the garage. The garage consumer unit would then just have a mains switch and MCBs for each circuit.


    I intend to run a ring main for sockets all round the garage, a radial for three florescent lights and potential a radial high amp outlet for a welder.
     
  2. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    firstly, the SWA itself does notneed RCD protection unless the house is TT earthing. better to fit RCD in garage, then a fault in the garage will trip in the garage, not the house. Secondly, should be no problem burying SWA in concrete floor, but I'd duct it.
    you could fit a 63A MCB (house end, non-RCD), then sub-board in garage with RCD and appropriate MCBs.
     
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  3. Paignton pete
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    Paignton pete Regular EF Member

    Location:
    Over the rainbow
    If your running twin and earth you will need rcd protection if depth of cable is less than 50mm deep in walls and floors. There are a few other criteria too you would need rcd protection for. Also you need to know the correct zones for running the cable.

    However you don't need rcd protection of the supply cable if your running it in SWA.

    Peter

    Edit: Bugger beat me to it tel
     
    • Agree Agree x 1
  4. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    Thank you for your prompt responses.


    Can I ask what sort of ducting would be ideal to run the SWA in and why I need the ducting if its SWA?


    Do I need RCD protection if I am less than 50mm but in SWA?


    In terms of zoning I am struggling to find info as most diagrams show wall and ceiling wiring zones. I am simply going through the hall and lounge floor to the outside.


    My house is a new ish one using TN-C-S earthing


    Regards,
     
  5. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    May be you should get a local spark involved and if you are in England or Wales this work falls under part p
     
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  6. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    ducting protects the SWA from any possible reaction with the concrete, and also gives it that extra protection from mechanical damage to the sheath. any 2" or thereabouts plastic duct will do. zoning applies mainly to cables buried in walls. there's a perfect diagram in OSG.
     
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  7. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    Thanks,

    Whats everyone thoughts on running twin and earth through insulation. Does it just need up-rating for heat dissipation? or should it be run through conduit?
     
  8. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    Can I also ask that if I pay a sparky to install a ring with a few sockets and a few lights. Can I add to the ring and lights without notifying the authorities?
     
  9. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    Said spark needs to do the sub main and the initial circuits ....
    After that it's possible for you too make changes to said circuit.

    What do you plan to use in the garage?
     
  10. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    think basic sockets and lights initially, but he stated he was planning on getting a welder. the load of the welder need to be considered before designing the installation.
     
  11. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    ^^ hence my closing sentence .....
     
  12. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    I am an engineer by profession and have a welder, lathe and mill. I need a sub main, socket outlets and lights. Potentially a higher rated fused outlet for a welder. If i were to add more sockets or lights I would hope its something I can do without need it signed off again? As long as I am not adding another circuit to the sub main?

    I assume in the garage I can just run the twin and earth clipped straight to the single leaf wall or through conduit?
     
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  13. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    The welder will be pulling 45 Amps, just checked and the power is 11kw
     
  14. Strima
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    Strima Electrician's Arms

    Location:
    St Neots
    What rating is the DNO fuse?
     
  15. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    I have a 100amp supply so assume 100Amp
     
  16. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    All electrical work should be carried out in accordance with BS7671, this includes inspection, testing and certification of the work. Notification for the purpose of part P however wouldn't be required for the extension of the circuits if not in a special location.

    Clipped direct cables would not be appropriate to the workshop kind of environment, I think the most suitable option would be steel conduit due to the risk of damage to the cables from weld spatter, metal chips and general moving of materials and heavy tools.
     
    • Agree Agree x 2
  17. David M
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    David M I'm often blinded by simplicity Electrician's Arms

    Location:
    Staffordshire
    I assume this is an arc welder? It will most likely require hard wiring into an appropriate rated isolator. During use of the welder you may notice a voltage drop which will cause lights to annoyingly flicker. Long continued use will cost you dearly in your electricity bills. (just some friendly advice)
    From experience, if you intend to use this as a "professional" workshop then be aware that the council/authorities may get involved and you will require planning permission.
     
  18. Loki
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    Loki Trainee Trainee Access

    Location:
    Devon
    Hi,

    Where did you get that 100 Amp from?
    If it was on the dno's main fuse housing then the fuse inside could be less.
    As your not ment/allowed to pull the main fuse "but people do i know lol" you would need to call you supplier & confirm this.

    Michael
     
  19. Loki
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    Loki Trainee Trainee Access

    Location:
    Devon
    Deleted double posted for some reason
     
  20. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    Why do I need to know this?
     
  21. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    ^^ very simply if it's a 60a then the combined load of the house and garage could easily blow out.

    Me thinks you need to consult a decent local spark.

    Where are you based?
     
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  22. FatAlan
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    FatAlan Trainee Trainee Access

    Location:
    Surrey
    Sounds like a good workshop. You're not Colin Furze by any chance? :D
     
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  23. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    Ah I see. Well I was applying the rules of diversity and the fact I dont have one electric shower or similar in the house so the welder basically pulls a similar current. My showers and rads are all gas. The 100amps came from the fuse located near the meter and the main switch in the consumer unit.
     
  24. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    I can only dream! Well its my first house and the garage is big enough for a decent workshop. I am employed full time so main use will be home projects.
     
  25. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    100 a on a main switch is normal and 100 a on a fuse carrier gives the max rating so nothing can be assumed...
     
    Last edited: Aug 16, 2017
  26. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    I see. well my current housing circuit has two 80 amp RCD's
     
  27. Pete999
    Online

    Pete999 Trusted Advisor

    Top Poster Of Month

    Location:
    Northampton
    Thought "The Doctor" knew everything, are you sure this isn't a neww bit of kit you're installing in the "Tardis" if you're doing it yourself make sure you torque the connections with you Sonic screwdriver.:D:rolleyes:
     
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  28. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    Which also means nothing helpful
     
  29. TheDoctor
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    TheDoctor EF Member

    Location:
    Bristol
    How can I find out the actual rating?
     
  30. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    For the main fuse #18
     
    • Like Like x 1
  31. TheDoctor
    Offline

    TheDoctor EF Member

    Location:
    Bristol
    so how much is it going to set me back to get a sub main installed in the garage with 1 32 ring and a lighting radial? roughly speaking. Assume the swa channel is already chased.
     
  32. Pete999
    Online

    Pete999 Trusted Advisor

    Top Poster Of Month

    Location:
    Northampton
    Get an Electrician in ti give you a quote, simples.
     
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  33. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Roughly speaking somewhere between £500 and £5000.

    Or in other words how on earth can anyone give a price without actually knowing what they are pricing for?
     
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  34. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    A little harsh davesparks the OP is only asking. OP, the only real way in any case, to get this work done is by a qualified competent electrician, its a bit more than putting up some lights you've got from B&Q. Think Pete suggestion is the way to go.

    PS your electrician might suggest you doing some labour work, like trench/chasing for your supply cable, which may save you some pounds.
     
    • Agree Agree x 2
  35. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    And I'm only answering, do you think the price won't be somewhere between those two,figures?
     
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  36. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    Would you speak to your potential customers like that?
     
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  37. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    what's the point of pussy-footing around. davesparks is right. nobody can give a more accurate estimate without physically seeing the job and pricing up equipment and estimating a timescale.
     
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  38. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    It was actually quite mild reply from davesparks, but I kinda sensed the next few wouldn't be. Anyway, whichever your viewpoint the OP seems to have taken on-board the advice :)
     
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