Voltage drop on a shower causing a light to come on

Hi everyone I was hoping someone might be able to help I came across a video on YouTube where when the shower was turned on it caused the bathroom light to glow while the switch was turned off. The person later explained it to be a voltage drop on the shower but to my understanding something like that wouldn't have that kind of effect ant guidance would be great thank you. 

Parents
  • Okay i believe I understand so the load neutral would then receive an extra 5 volts am I understand that right? 

    In a way, yes. A diagram might help:

    If you like the relative voltages, in red, show the voltage differences across each part (cable and load), whereas the blue figures show the voltages relative to Earth.

    But none of that directly explains why the lamp glows. If it's an incandescent, a substantial current must be available (much more than capacitive coupling would normally provide) and if the light were conventionally switched and the switch in the off position, there shouldn't be a path for such a current. There must be something odd with the setup or a  fault somewhere.

       - Andy.

  • Ah okay so across the line conductor where lossing 5v and then again across the load we lose a further 5 volts which goes down to earth and the neutral conductor. 

    Currently I am only a 3rd year electrical apprentice I was wondering if there was any materials I could read into to understand this all better 

    Thank you. 

Reply
  • Ah okay so across the line conductor where lossing 5v and then again across the load we lose a further 5 volts which goes down to earth and the neutral conductor. 

    Currently I am only a 3rd year electrical apprentice I was wondering if there was any materials I could read into to understand this all better 

    Thank you. 

Children
  • we lose a further 5 volts which goes down to earth and the neutral conductor. 

    Erm, voltage is probably best thought of as a pressure difference between two points - volts don't travel as such. It's the current (amps) that flows - and flowing along something with resistance (which everything has) results in the pressure drop (voltage difference). Text book wise it's all just Ohm's Law. V=IR. You've got the same current flowing through all parts of this simple circuit - the overall current is regulated by  the overall resistance of the circuit (load and all the connecting wires) and the supply  voltage as a result is divided up across each component of the circuit - so the voltage of across each part in series adds up to the original supply  voltage. There's nothing special about the N conductor in this regard - it carries current and has a voltage difference along its length in exactly the same way as the line conductor.

       - Andy.