110V vs 230V - a dumb question?

Discussion in 'Electrics UK' started by sparkybird, 15 May 2005.

  1. sparkybird

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    If it is accepted that a 110v supply to power tools is safer, why can you buy 230V ones which work directly off the mains? :confused:
     
  2. breezer

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    110v tools are for on "site" use, 230v tools are not. 110v actually hass 2x 55v (giving 110) which is safer try a search on these forums there has been a debate about it
     
  3. Big_Spark

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    The reason that 230V is used is more to do with transmission issues and voltage loss on circuits.

    As Breezer has pointed out 110V construction site supplies are actually 2x55V (effectively dual phase) and it has no neutral conductor. 230V mains is 230V to Neutral/CPC.

    Another factor is cable size, 110V requires a cable at least twice the size of 230V as the current is higher if the voltage lower.

    Example> 10A @ 230V = 21A @110V

    The main reason for the use of 110V in the UK construction industry is safety. Building sites are inherently dangerous by their very nature, and cables are damaged on a regular basis, especially those feeding power tools and lighting. By using dual 55V, the voltage lacks the energy to push a fatal current through the body of a human being, so the odds of fatality by electric shock is reduced to almost nothing.

    On the continent they use 230V power tools and lighting on construction sites, and every year their death rates contain a significant number of electric shock victims.

    The use of such supplies in the home (110V dual phase) are impractical for many reasons.
     
  4. sparkybird

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    I understand why the 110V is safer and how you use a transformer to step down the voltage, but my query (perhaps badly worded) was how come if you are not 'on site' that you can use 230V, which is potentially more dangerous? What qualifies as 'on site'? Is a DIYer really going to be more careful than a tradesman (hmm, maybe don't answer that?!) :oops:
     
  5. supersparks

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    well think of a big site....

    plant flying arround, 100s of personel, some can't speek english...lets not go there....high rise scaffolding and tend to cover HUGE areas


    then think of the resedential sites....

    probrably no more than 4 guys on site which probrably is no bigger than 50meters2

    maybe some scaffold, not generaly going up 10 storys :LOL:

    as for DIY, lets not go there
     
  6. sparkybird

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    Thanks everyone - a useful discussion. I guess it also relates to what you call a 'site'. I tend to work on domestic stuff with 1 or 2 other people, so I can see that this is inherently less dangerous than a big construction site (although some of their english is appalling!!) :D
     
  7. Big_Spark

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    Sparkybird, I now understand what your referring too, and the answer is simple, if a professional in undertaking any works on any location that requires the use of power tools, then regulations state that only 110V power tools may be used.

    Obviously there are situations where this may not occur, like in the tradesmans own home, but to be honest I do not know any tradesman that own 230V power tools, with perhaps the except of something so specialised it cannot be obtained in 110V..I have a professional heat gun that fits this description, I have hunted high and low for the 110V equivilent, but alas not found one.
     
  8. sparkybird

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    Thanks FWL. Are you able to quickly point me to the right section of the Regs? Otherwise, I'll flog through them...
    SB
     
  9. andy

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    same here. the only 230V power tool i have is a spare drill. everything else (including floodlight) is 110V. no point in havin 110V for on site and 230V for domestic... just as easy to use 110V
     
  10. Big_Spark

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    It's not the Electrical Regs SB, it is in the Health and Safety at Work Act (HSAW) in the section that descibes the specific regulations for Construction sites and other hazardous locations. There are also a few paragraphs that deal with this thorny issue in the Electricity at Work Regulations (EWR)and the Management of Health and Safety at Work Regulations Acts(MHSWR).

    I have a handbook for some of this somewhere, I will try to hunt out the specifics and post here, but it may take a few days as I have a lot of work on at the moment.
     
  11. supersparks

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    also allowed is 230v used on sites
    but must have RCD protection at 30mA
    and also disconection time max of .2seconds if i remember correctly.

    personly i like to see 110v wheather its domestic or not, a risk is still present and having 110v might save your life, what is anoying is site lighting in 110v is usualy a few quid more expensive than 240v
     
  12. plugwash

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    can't you just swap out the bulbs?
     
  13. sparkybird

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    Supersparks - are you saying that a 30mA RCD would be OK to use on a 230V tool (ie instead of 110V)? Also, I thought that socket disconnection times were 0.4s, so how would that work? :?:
     
  14. delmel

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    I think what he is stating is clear.

    110v = Trades on site works. This you will find is a requirement using a step down transformer.

    240v is for home and general DIY use, no longer accepted on Trades sites but acceptable to use at home.
     
  15. mapj1

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    So do ours of course, but here they are mostly involving scaffold poles and overhead cables...
    Do you have any source of 230v accident numbers where the figures may be compared - I'd be most interested to know how significant this benefit really is, or if its just the same "British Disease" that bans sockets in bathrooms, and has over engineered plugs, and source impedances so low that the fault currents are embarrasing just because it felt like it ought to be better on principle, or if there is a real, measurable safety gain.
    I only have the overall accident figures at the moment, not divided by occupation.
     

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