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    110V Fluorescent Lighting on a construction site

    In the UK I understand the method of connecting 110V (construction site voltage) fluorescent tubes festooned along a construction site is as follows.
    415V to transformers. Earthed centerpoint of a Wye (Star) connection, with the light connected in delta accross the points of the Wye (Star). This gives you 110V between phases and a max of 62V from the earthed center point. Is this correct?? What is the transformer type which you would use for such a circuit. Thanks!!

    #2
    Originally posted by Robdriver View Post
    In the UK I understand the method of connecting 110V (construction site voltage) fluorescent tubes festooned along a construction site is as follows.
    415V to transformers. Earthed centerpoint of a Wye (Star) connection, with the light connected in delta accross the points of the Wye (Star). This gives you 110V between phases and a max of 62V from the earthed center point. Is this correct?? What is the transformer type which you would use for such a circuit. Thanks!!
    I do not want to appear rude, but what kind of engineer are you? What you posted does not make sense to me.

    My understanding is the UK uses a 415/240 Wye (Star) secondary in their power system. The voltage between any 2 phases would be 415-volts and the voltage to the "earthed center point" to any phase would be 240-volts. In order to use 110-volt equipment you would have to buy the transformers and lighting from a source that uses a different power system.
    Lou (wannabe economist)

    If you relentlessly pursue perfection, you will eventually catch excellence.

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      #3
      Originally posted by hardworkingstiff View Post
      I do not want to appear rude, but what kind of engineer are you? What you posted does not make sense to me.

      My understanding is the UK uses a 415/240 Wye (Star) secondary in their power system. The voltage between any 2 phases would be 415-volts and the voltage to the "earthed center point" to any phase would be 240-volts. In order to use 110-volt equipment you would have to buy the transformers and lighting from a source that uses a different power system.
      If physically possible, could you tap the center point of one of the wye windings to get 120V?

      Comment


        #4
        Originally posted by mull982 View Post
        If physically possible, could you tap the center point of one of the wye windings to get 120V?
        I guess that would work. One leg would be 240-volts to ground and the other would be 120-volts to ground. That would blow someone's mind. Could you legally/safely feed a panel with that?

        So you would have to order all of your lighting from.... USA? We are 60hz and they are 50hz. Would that make a difference?
        Lou (wannabe economist)

        If you relentlessly pursue perfection, you will eventually catch excellence.

        Comment


          #5
          Originally posted by hardworkingstiff View Post
          I guess that would work. One leg would be 240-volts to ground and the other would be 120-volts to ground. That would blow someone's mind. Could you legally/safely feed a panel with that?
          I guess this would be similar to a 120/240 3-phase delta in that you would have multiple voltages to ground. You just could not take all three hots and the center tapped 120-volt leg into the same panel unless you had it specially made. You would have to have the transformer specially made.
          Lou (wannabe economist)

          If you relentlessly pursue perfection, you will eventually catch excellence.

          Comment


            #6
            The normal practice in the UK in building sites is to power portable lighting from an isolating transformer.
            Two principle types exist, the smaller ones have a single phase primary winding to suit the normal single phase supply of 230/240 volts. The secondary winding is single phase 110 volt nominal with an earthed center tap.
            This ensures that the maximum voltage to earth is only 55 volts, thus almost eliminating the risk of dangerous electric shock.
            Such transformers are generaly portable and fitted with a short length of cable and a 240 volt plug. Common ratings are from 500 watts up to 3,000 watts, though larger units exist.

            The second type has a three phase primary winding to suit the UK 400/415 volt supply.
            The secondary winding is three phase Y (or star as we say in the UK) with the neutral earthed, the voltage 110 volts from phase to phase, and 62 volts phase to neutral. The neutral point is earthed, and the 110 volt loads are connected from phase to phase. This limits the voltage to earth to about 62 volts, and therefore greatly reduces the risk of dangerous shock.
            Such transformers are sometimes fitted with a length of supply cord and a three phase plug, but are more commonly hard wired via armoured cable.
            The most common ratings are from 6,000 up to 12,000 watts, though other sizes exist.
            Sometimes a three phase 110 volt output is provided, but the main use of these transformers is to supply a number of single phase 110 volt lamps or tools etc.

            110 volt lighting or power tools are normally connected to either type of transformer via extension cords with suitable plugs, dedicated to 110 volt use.
            Such transformers are sometimes used to supply fixed wireing in workshops etc. but they are commonly used on building sites.

            Suitable transformers, complete and ready for use may be purchased from any large wholesaler in the UK.
            Note that the manufacturers rating often assumes only intermitant use for hand tools etc. For continous loads such as lighting the size of the transformer often has to be doubled.

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              #7
              Thanks Broadgage. Do they (UK) just do this on building sites (I assume you are talking construction sites) or do they also do this in occupied buildings?
              Lou (wannabe economist)

              If you relentlessly pursue perfection, you will eventually catch excellence.

              Comment


                #8
                Originally posted by hardworkingstiff View Post
                Thanks Broadgage. Do they (UK) just do this on building sites (I assume you are talking construction sites) or do they also do this in occupied buildings?
                Such supplies are normally used in buildings undergoing consruction or major repair/refurbishment/alteration.
                It would not be usuall to use 110 volts in buildings normally occupied, rather than occupied only by the builders etc.

                Some employers or clients insist that all portable electric tools used for maintenance or repair, are worked from a 110 volt transformer, even for very minor works in an occupied building.
                This requirement is becoming less common, and IMHO was allways unreasonable.

                Some factories and workshops use 110 volts for hand tools, but this is also becoming less popular.

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