Electrics into a detached garage.

Discussion in 'Electricians' Talk' started by Mike the Crowbar, Aug 5, 2015.

Page 1 of 2
  1. Mike the Crowbar

    Mike the Crowbar New Member

    HI,

    I know there are several threads about electrics into a detached garage, but can't find the questions i have, covered in other posts.

    I have a detached garage 8m (straight line from house main panel).
    I am looking installing an electric roller door, 4 double sockets on a ring main and then lights.

    1, do i use dig in armoured cable (at the correct depth) or bury metal/plastic conduit and run un-armoured cable? are both options viable and legal?

    2, If using conduit, can conduit wiring be used (at the correct rating), or run twin & earth?

    3, installl one run for garage door electrics, and one for the ring main & lighting circuits?

    Thanks in advance,

    Mike
     
    Mike the Crowbar, Aug 5, 2015
    #1
  2. Deleted member 33931

    Deleted member 33931 Guest

    Do whatever you prefer.

    Unless you really need the conduit to, perhaps, run additional cables in the future (communications, internet, that kind of stuff) then I'd personally chust go armoured cable. And chust one of them...

    BUT, be clear about the max load you'll need in the garage, and future-proof it too. Roller door and lights take very little, but what are you expecting to run off your sockets? A welder, by any chance...?
     
    Deleted member 33931, Aug 5, 2015
    #2
  3. rd1

    rd1 Member

    My Hormans sectional, double width, with garador motor is just run off a 13 amp plug as part of the new radial circuit.
     
    rd1, Aug 5, 2015
    #3
  4. sparky Si-Fi

    sparky Si-Fi Screwfix Select

    You will have to consider letting a spark install this as this is under building regulations and out of the scope of a DIY'er

    Burying Twin and skin. .?

    Not how it is to be done correctly

    Si
     
    sparky Si-Fi, Aug 5, 2015
    #4
  5. Deleted member 25896

    Deleted member 25896 Guest

    The more usual way would be a SWA sub main to a small DB in your garage. From DB2 you would then run the necessary circuits within the garage. Then comes the technical bit, sizing your SWA, the type of earthing you have (just don't mention exporting PME or you'll have 2000 posts by tomorrow), the house CU (is it a dual RCD, does it have a non RCD spare way, how are you going to get your SWA to it and how will you terminate it). The list is endless. Anyway to answer the OP, SWA.
     
    Deleted member 25896, Aug 5, 2015
    #5
  6. stateit

    stateit Screwfix Select

    You wouldn't use conduit, you'd use continuous ducting instead.
     
    stateit, Aug 6, 2015
    #6
  7. Mike the Crowbar

    Mike the Crowbar New Member

    Twin and Skin wouldn't just be buried, i would run it through suitable ducting/conduit.
     
    Mike the Crowbar, Aug 6, 2015
    #7
  8. Mike the Crowbar

    Mike the Crowbar New Member

    that was my point 3, single run to DB in garage, then split out from there. this was the way i thought was best, but someone suggested seperating the door and ringmain/lights from the house end. I will look at a larger armoured cable (16mm² i think goes up to 40 Amps?) then split for door/ring main/light circuits. on a DB in garage.
    If i put the cable in at the right depth, whilst i'm having other work done in the ground, is there an issue getting it certified, or would it need to be buried by the person certifying it. Would this be the same for the ring main and light circuits or am i able to do most of the install and just have the final connections done by a qualified person?
     
    Mike the Crowbar, Aug 6, 2015
    #8
  9. Mike the Crowbar

    Mike the Crowbar New Member

    I'll probably used PoE if i do need internet etc in the garage so will look at single Armoured cable. sockets would be running hand tools, nothing drawing to heavy a load, drill, worktop lathe, scroll saw, bench sander etc. Only going to be me using, so not going to have much more than a radio, laptop maybe, and one tool at a time on the ring main. wouldn't be welding, more woodwork.
     
    Mike the Crowbar, Aug 6, 2015
    #9
  10. Mike the Crowbar

    Mike the Crowbar New Member

    I say conduit because i didn't know what the other stuff was called, thanks. continuous ducting was what i meant.
     
    Mike the Crowbar, Aug 6, 2015
    #10
  11. sparky Si-Fi

    sparky Si-Fi Screwfix Select

    Burying Twin and earth is NOT advised, you will have to provide mechanical protection for the cable.

    NO spark alive would pull in Twin and earth in Black or Galv. conduit and put it in a trench

    SWA is the only cable designed to be buried

    Do you know what depth it has to be buried. .?
    Who is going to certify all this work. .?

    " Only going to be me using"

    You say that now but that's not guaranteed forever the life of the instalation

    "is there an issue getting it certified, or would it need to be buried by the person certifying it."

    Yes. .SELF CERTIFYING ELECTRICIAN will install to current regs if HE is doing the job

    Using a Licence number for non-installed work will be a challenge and all the best with that when at a later date something is not quite right. . .Believe me.

    OR

    YOU notify LABC BEFORE work starts

    Sorry bud but you sound like a bloke who is asking every question on how to DIY this job

    My advice. . get a spark in as its HIS job to do and you will be saved a lot of stress

    All of this falls in with BC and Part P and WILL have to be notified by the SELF certifying sparks
     
    Last edited: Aug 6, 2015
    sparky Si-Fi, Aug 6, 2015
    #11
  12. sparky Si-Fi

    sparky Si-Fi Screwfix Select

    sparky Si-Fi, Aug 6, 2015
    #12
  13. Mike the Crowbar

    Mike the Crowbar New Member

    First of all, thanks for the help and advice. I'm not being rude, this is why I came on here to ask the questions.

    I'm about to have a patio laid and don't want to have to dig it up( or have it dug up) when I get round to putting(or getting done by a pro), electrics into my garage. If ducting is the way, I'd get it put in beneath the patio whilst the patio is being laid. Or if SWA, get that laid (is it at 500mm,with warning tape at 100m depth) whilst patio being done, ready to be terminated when I get electrics done. Making sure it was weatherproofed and secure once in place to save damage to the cable. Would photographic evidence of cable being laid, with measurements within the photographs be enough for it to be able to be certified by an electrician, or would the professional builder be the one to certify the depth the SWA is laid at? Again, this is why I'm asking the questions.

    It's only going to be me using my garage, I'm not going to install the capability to go to 100Amps or 3phase just in case I sell in the future, and happen to sell to someone doing heavy welding etc. I just want lights, a radio, and a place to retreat to enjoy my hobbies, a mini man cave. It's a single residential garage.

    I sound like a bloke asking questions on how to DIY the job, basically because I do want to DIY as much of the work as I possible, I also don't want to have to dig up a recently laid patio to put SWA or ducting underneath if I can do it while the patio is being laid. I've been a telecoms engineer for about 20yrs, and as I'm sure you'll appreciate, is a very similar job, just different voltage levels and regulations. I believe I have the skill sets to do most of the work but am unsure of the legalities of electrics. Installing (subsurface or within buildings) and terminating Fibre optics, coaxial or cat5 in conduit or ducts, or armoured cables, are not physically that different(other than fibre tend to need a little more care). Terminating in to wall boxes, mainframes or patch panels similar too. so running conduit around u garage for electric sockets is not dissimilar to running conduit around an office with cat5 terminating boxes. Only the cables within and the boxes on the end. I just want to do as much as I legally can myself, without making it difficult to get it certified.

    a bit like if your car needs work doing to pass an MOT, and you are able to do most of the work yourself, you wouldn't pay a garage to do that work for you, would you?
     
    Mike the Crowbar, Aug 6, 2015
    #13
  14. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    I understand your simile to a MOT, but a MOT is a test that proves only that a vehicle is at the moment of the test, in proper condition. Nothing to do with it's lasting performance. Nothing to do with how well it has been installed or serviced, but that it works now.

    An electrician must certify not only that it meets requirements now, but continues to be safe and proper throughout its life. If he hasn't installed it, he may not say that he can trust the install has been properly done.

    Mr. HandyAndy - Really
     
    Mr. Handyandy, Aug 6, 2015
    #14
  15. Deleted member 33931

    Deleted member 33931 Guest

    Hi Mike.

    My understanding is that buried cable has to be either armoured or protected within a conduit with a similar resistance to damage.

    Personally, SWA is the way to go - thinner, easier, everythinger.

    Depth is not specified other than it should be deep enough to suit the environment - ie be unlikely to be reached and damaged with normal activity.

    So, under a paved patio, it is very unlikely that anything will get anywhere near the cable, so even a few inches 'should' be fine. Under a flower bed is a different issue, so - say - a spade and a half's depth would seem reasonable.

    Want a ballpark depth? Ooh, 500mm+. Don't forget your warning tape a few inches above.

    The simplest cable to run is SWA. Only run a single cable as this will serve everything you want - door, lights, a few power tools, music, etc etc with ease. Size of cable needed for this? Surely for no more than 20 Amps? In which case 4mm2 SWA should be fine for an 8m distance.

    Or go for 6mm2 to be sure to be sure.

    All you need in your garage is a 2-way CU with an RCD main isolator, a 20A MCB for the sockets and a 5A one for the lights. Your garage door will chust plug in to one of the sockets - peasy.

    So, lay your cable, build yer patio, and then get a sparkie to connect it all up if you ain't happy.

    Make sure the armour strands are earthed - use the correct fixing glands for this.

    At the house end, you may find it easier to connect the SWA to normal T&E cable once it's through the wall for ease of running, lower cost and making the connection to the house's CU easier. Wire it to a separate 20A MCB in the house's CU.

    Make sure you run the SWA through a short length of plastic conduit (I used 25mm MDPE water main pipe...) as it passes through the house and garage walls.

    Jobbie jobbed.
     
    Last edited by a moderator: Aug 6, 2015
    Deleted member 33931, Aug 6, 2015
    #15
  16. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Haven't you just put a possible 25A in the garage on a 20A mcb ?

    Mr. HandyAndy - Really
     
    Mr. Handyandy, Aug 6, 2015
    #16
  17. Mike the Crowbar

    Mike the Crowbar New Member

    Thanks, I understand that, but I can't see how it can be certified for throughout its life, or has that been brought in so houses won't need to be rewired in the future? Are we talking Main RCD panel in house DP in garage or all electrics in a house/garage?mDoes that mean you need to get and electrician to change light fixtures and plug sockets at a later date?

    Maybe I'm missing the point, if the cables are run, left for a qualified sparky to terminate the sockets and lights, and to terminate at the main panel and RCD panel that would be in the garage, he would be reluctant to certify. Or would he need to dig up the patio, lay the cable then re-lay the patio, install the DP, fit conduit and run cables within, terminate everything, to certify. Are electricians qualified in landscaping/building also? Sounds like I should hold off and get an electrician in at the same time as getting the patio laid, crazy world we live in where you have to pay someone to do a job where you can do most of the donkey work yourself. No wonder people are getting lazy.

    Serious point, I'm getting tired of comms, if I re-traded and became qualified as an electrician as I've got most of the skills already anyway, would I be able to certify the work myself, on my own home( it's a new build as apposed to an older property) or would it still have to be done by someone else.
     
    Mike the Crowbar, Aug 6, 2015
    #17
  18. Deleted member 33931

    Deleted member 33931 Guest

    Oh gawd, the pedant is still up...

    20A max for the whole cable supply (depends on what size cable you use).

    This could, in theory, be a full 20A from chust the garage sockets, or 15A from the sockets and 5A from the lights... Max.

    In practice, neither should come close. But the supply to the garage is protected by an appropriate MCB in the house.
     
    Deleted member 33931, Aug 6, 2015
    #18
  19. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    'Throughout its life' yes. Until it no longer performs as it should or begins to die from old age etc. Fixed wiring(generally hidden) is supposed to be there for its life(unless it fails to perform for some reason).
    If Building Control were in charge, they may want to see the installation happening at every step before they sign it off.

    Mr. HandyAndy - Really
     
    Mr. Handyandy, Aug 6, 2015
    #19
  20. Deleted member 33931

    Deleted member 33931 Guest

    Mike, if you are really intending to have a qualified sparky come in to connect up at both ends, then he will want - I'm sure - evidence that the cable has been buried to a depth that satisfies him. 'Cos he's the one whose name will be on the cert.

    Some sparkies will be more pedantic than others. Some will no doubt insist on a 'full' 600mm depth, or possibly even more. Others may well say that 6" for the part under the patio slabs is perfectly ok.

    So, you are taking a risk.

    So, you could try a reasonable depth as mentioned in my last post, and take photos to show the future sparky, or else do what you believe to be reasonable, and then finish off the wiring job as well.

    But only if you are sure you have researched it properly. (And are happy to break what is presumably a Part P law?)
     
    Deleted member 33931, Aug 6, 2015
    #20
Page 1 of 2

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Accept Learn More...
    Dismiss Notice