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Plug in RCD 230V or 110V transformer

Former Community Member
Former Community Member
I'm curious to see what peoples opinions are on the two different options available for safer power tool use either using 110V tools with a site transformer alone or 230V tools however using these with the plug in RCD. 


I'm aware of the center tapped site transformer splitting the voltage into 55V so there is the arguement that it's only 55V pushing through your body, vs the RCD option, you're exposed to the potentially full 230V but the RCD cuts the supply almost instantly. However this is based on the RCD actually working and detecting a fault and even if it does perhaps even that brief exposure to 230V may be enough for some people to be fatal. Then again 55V maybe enough for some people too to be fatal. 


Thought?


  • 0
    Has anyone ever died from an electric shock whilst using a 110 volt centre tapped tool?
  • 0
    To the best of my knowledge there has never been a fatal electric shock with the 55-0-55 RLV system.


    The RLV system achieves what RCDs achieve by disconnection time - but without a "failure mechanism" in the case that an RCD does not trip.


    RLV every time for me - or better still, battery tools.


    Another cautionary note is that BS 7288 is the PRCD standard ... and the current version of this standard assumes additional protection and fault protection is already provided upstream in the electrical installation.
  • 0
    Definitely use the transformer supply think about it on a building site RCDs can be dropped kicked or otherwise abused usually resulting in them falling apart transformers on the other hand are much tougher  and although they can still be subject to damage they won't simply stop working j
  • 0
    Rather depends how it is implemented. Fine if you have 110v generation on the ground in the clean and dry and then the required 110v distribution, less so if the 230V trails most of the way to the destination anyway and then a rather beat-up hand carry transformer sits in a puddle of dirty water just beside the 110V cement mixer or whatever.

    The one I really did not like was looking up up to see a chap using a kango type thing to demolish an overhead archway, but the transformer balanced on the broken brick quite near the edge and poised to drop about 10 feet to the floor as he moved along if he pulled the cable tight.

    Luckily he spotted it  in time, but even so, that sort of job might have been better on 230V.

    Mike.
  • Former Community Member
    0 Former Community Member
     the arguement that it's only 55V pushing through your body,


    I did try and follow the pages of mathematics many years ago that a very clever forum member did, which showed that the actual voltage was lower than 55 V, nearer 45 V from memory. 


    I struggled then, so now I wouldn't even try!


    Regards


    BOD




  • 0
    perspicacious:
     the arguement that it's only 55V pushing through your body,


    I did try and follow the pages of mathematics many years ago that a very clever forum member did, which showed that the actual voltage was lower than 55 V, nearer 45 V from memory. 


    I struggled then, so now I wouldn't even try!


    Regards


    BOD

     


    From what I remember, there was a bit of additional complexity (to do with power factor?), but the worst case came from the 3-phase RLV system - with 110V between lines and so around 63V between L and Earth. Then with a TN system equal sized L and PE conductors the maximum voltage at the point of a L-PE fault will be around half that.


    As I understand it RLV is a UK peculiarity - the rest of the 230V world has never heard of such a thing and just uses 30mA RCDs. As a result of harmonization all the standards deem 230V+RCD as acceptable, but there is still a strong preference for RLV in the UK and many individual sites still insist on it.


       - Andy.


  • 0
    I'm not sure if you are in a factory or building site, but in my factory, years ago, we stopped using 230v tools and phased them out in favour of 110 RLV tools with portable transformers.


    the HSE expect them, NEBOSH courses are in favour, and they are generally accepted as a good way to make things safer. In court, you would be in a much better position.


    One thing to do, is stop issuing 230v extension cables, but make 110v ones readily available, this will prevent the transformers from being damaged, and results in less 240v on the floor. 


    You can distribute the 110v using centralised larger transformers, the very big ones are 63v as above, but still much safer than 230v


    If you look at the cost of RCD sockets, or RCBOs, the RLV system looks attractive, and the old excuse of tools not being powerful enough is utter nonsense.
  • 0
    You do need to stop folk trying to fit RCDs to the RLV system though ?

    I think large sites where 110V can be centrally generated  it certainly makes sense, rather less so for jobbing builders working in peoples homes, the transformer is just another luggable thing to get damaged or to give someone back problems.

    M.
  • 0
    mapj1:

    You do need to stop folk trying to fit RCDs to the RLV system though ?

    I think large sites where 110V can be centrally generated  it certainly makes sense, rather less so for jobbing builders working in peoples homes, the transformer is just another luggable thing to get damaged or to give someone back problems.

    M.


    you can buy them, designed to wire into the outgoing socket side of a portable unit. but I have seen them fitted to the 230v plug too


    in a domestic setting, I think there should be little use for mains hand tools now battery tools are so good. I do agree that a transformer should only really be set up once a day, if it needs moving more than that, its time to look at alternatives


  • Former Community Member
    0 Former Community Member
    Well thanks for the responses, seems that the transformer is the way to go over the RCD. Most of my power tools are corded at 110V. I do like the battery tools but still don't think they are quite there yet compared to battery tools for the bigger consumers such as mitre saws and circular saw. I've literally watched people with the Dewalt flexvolt system get no more than 12 cuts in sheets of ply before the battery is done. Given my work it is easy in most situations to set up my 3.3KVA transformer outside or in a customers garage and if necessary run a 110V extension, though I rarely have to most of my tools have long enough leads on them. The 0.75KVA will be kept closer to power the smaller tools such as the multitool etc. Again I have seen the battery equivalents die after just 20mins of use. 


    The reason for asking the above question is that it looks like I'll have to buy a bigger transformer for the intended 2100W router, the 3.3KVA transformer only has 2 16Amp sockets so I need a new one with a 32Amp socket and may as well get a 5.0KVA so can run the router for more than 5-8mins. The router will be the only tool I have that will require the bigger transformer, all my other tools are at or below the continuous rating of the 3.3KVA transformer. That's why I was wondering for just one tool which will not be used on site ever, maybe rarely on a job, but mainly for home projects a 230V tool would suffice.

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