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Double pole switches for lighting

Kenneth Odam

I replaced an old fluorescent light fitting with an LED version - it had an emergency backup facility which required a separate unswitched live.

I took a live feed from an existing emergency light to my new fitting.

Everything seemed to work until I turned off the light - the battery charging light went off and the light came on at low power.

It turned out that the original light circuit had a double pole switch.  When it broke the neutral line the emergency light came on.

I bypassed the neutral side of the switch and the lights all work as expected.

I have never come across double pole switches used for lights.  Is there any good reason for this?

There is a double pole cct breaker upstream for maintenance work, so I don't think I'm creating a hazard.

In the unlikely event that the live side of the double pole switch breaks in the on position, the neutral switch would turn out the light but leave it all floating at live potential.  I can therefore think of good reasons not to use a double pole switch.

Thanks

Ken 

Retired MIET

Parents

  • "I have never come across double pole switches used for lights.  Is there any good reason for this?".

    In days of yore during my 5 year, student apprenticeship; we spent 6 months in each Scottish steel, tube plant. I was sent on my Jack Todd to fix a circuit in the laboratory of a dated plant; the lighting and power circuits were 2 phase. I remember when the lab manager asked why I was taking so long; I replied that "The fuse is OK but I can't find the neutral". This was my first experience with such 2 phase.

    The same plant where they had a working, coal fired, steam driven, mobile crane and a low pitched roof which collected smoke from the numerous coal fires around the shop floors. 

    Nostalgia ain't what it used to be!

    Jaymack         

Reply

  • "I have never come across double pole switches used for lights.  Is there any good reason for this?".

    In days of yore during my 5 year, student apprenticeship; we spent 6 months in each Scottish steel, tube plant. I was sent on my Jack Todd to fix a circuit in the laboratory of a dated plant; the lighting and power circuits were 2 phase. I remember when the lab manager asked why I was taking so long; I replied that "The fuse is OK but I can't find the neutral". This was my first experience with such 2 phase.

    The same plant where they had a working, coal fired, steam driven, mobile crane and a low pitched roof which collected smoke from the numerous coal fires around the shop floors. 

    Nostalgia ain't what it used to be!

    Jaymack         

Children
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