Rewiring a Hardwired Smoke Detector WITH THE POWER ON

Discussion in 'Misc DIY' started by gobofraggle@gmail.com, Apr 1, 2008.

  1. Guest

    I have a hardwired smoke detector that is old and outdated, that I'd
    like to switch with a new unit. The only problem is that I can't
    shut
    off the power to the alarm before I disconnect it and reconnect the
    new one. I'm going to have to do the take-down and installation
    while
    the power is LIVE.

    I live in a high-rise apartment building and the smoke detector is
    powered not by my unit's individual power, but off of a line brought
    in from a common hallway. There is no way to cut power to the smoke
    detector without cutting power to all the lights in the common
    hallway, which is impossible.


    So, how can I safely (or as safely as possible) change this detector
    with a new one? If I don't touch certain wires together, will I be
    OK? What are the chances I would get shocked?


    I know your first inclination will be to tell me to get the circuit
    turned off or call an electrician, but please (at least
    hypothetically) assume that neither of those options are possible.
    , Apr 1, 2008
    #1
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  2. ransley Guest

    On Apr 1, 5:32 pm, wrote:
    > I have a hardwired smoke detector that is old and outdated, that I'd
    > like to switch with a new unit.  The only problem is that I can't
    > shut
    > off the power to the alarm before I disconnect it and reconnect the
    > new one.  I'm going to have to do the take-down and installation
    > while
    > the power is LIVE.
    >
    > I live in a high-rise apartment building and the smoke detector is
    > powered not by my unit's individual power, but off of a line brought
    > in from a common hallway.  There is no way to cut power to the smoke
    > detector without cutting power to all the lights in the common
    > hallway, which is impossible.
    >
    > So, how can I safely (or as safely as possible) change this detector
    > with a new one?  If I don't touch certain wires together, will I be
    > OK?  What are the chances I would get shocked?
    >
    > I know your first inclination will be to tell me to get the circuit
    > turned off or call an electrician, but please (at least
    > hypothetically) assume that neither of those options are possible.


    When I wire with power on I carefully remove wire nuts or screws with
    a rubber insulated screwdriver and carefully rewire it, but if its a
    building unit why bother it probably works, test it, I cant believe it
    will set off others, but maybe call the manager. Gee, Free electric is
    what I see from the building, or maybe you know that, but you will get
    caught eventualy.
    ransley, Apr 1, 2008
    #2
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  3. Mikepier Guest

    On Apr 1, 6:32 pm, wrote:
    > I have a hardwired smoke detector that is old and outdated, that I'd
    > like to switch with a new unit.  The only problem is that I can't
    > shut
    > off the power to the alarm before I disconnect it and reconnect the
    > new one.  I'm going to have to do the take-down and installation
    > while
    > the power is LIVE.
    >
    > I live in a high-rise apartment building and the smoke detector is
    > powered not by my unit's individual power, but off of a line brought
    > in from a common hallway.  There is no way to cut power to the smoke
    > detector without cutting power to all the lights in the common
    > hallway, which is impossible.
    >
    > So, how can I safely (or as safely as possible) change this detector
    > with a new one?  If I don't touch certain wires together, will I be
    > OK?  What are the chances I would get shocked?
    >
    > I know your first inclination will be to tell me to get the circuit
    > turned off or call an electrician, but please (at least
    > hypothetically) assume that neither of those options are possible.


    Most of those 110V smoke detectors have a quick-disconnect plastic
    connector that you should be able to work with while the power is
    live. You would have to open up the detector and see if it does have
    one of those connectors. And plus you would have to make sure the new
    detector has a similiar connector. Usually they are interchangeable.
    If the old unit is hardwired with no connector, I would try to cut the
    power before working on it.
    Mikepier, Apr 1, 2008
    #3
  4. ransley Guest

    On Apr 1, 6:03 pm, Norminn <> wrote:
    > Jeff Wisnia wrote:
    > > wrote:

    >
    > >> I have a hardwired smoke detector that is old and outdated, that I'd
    > >> like to switch with a new unit.  The only problem is that I can't
    > >> shut
    > >> off the power to the alarm before I disconnect it and reconnect the
    > >> new one.  I'm going to have to do the take-down and installation
    > >> while
    > >> the power is LIVE.

    >
    > >> I live in a high-rise apartment building and the smoke detector is
    > >> powered not by my unit's individual power, but off of a line brought
    > >> in from a common hallway.  There is no way to cut power to the smoke
    > >> detector without cutting power to all the lights in the common
    > >> hallway, which is impossible.

    >
    > >> So, how can I safely (or as safely as possible) change this detector
    > >> with a new one?  If I don't touch certain wires together, will I be
    > >> OK?  What are the chances I would get shocked?

    >
    > >> I know your first inclination will be to tell me to get the circuit
    > >> turned off or call an electrician, but please (at least
    > >> hypothetically) assume that neither of those options are possible.

    >
    > > Do you know if your smoke detector is "powered" by a 120 volt AC line
    > > or by a low voltage line?

    >
    > > Do you know if the smoke detector sends a signal back to an alarm
    > > panel to notify an alarm company that it's been tripped, or does it
    > > just sound off in your place?

    >
    > > Do you know whether your "new" detector will be electrically and
    > > operationally compatible with the existing system(s) in all respects?

    >
    > > If you aren't certain about all the above, stay away from that job.

    >
    > > Further, I'd suggest you'd be much better off taking the matter up
    > > with the apartment building's management (if you haven't already)
    > > before you do anything to the existing detector. I'd hazard a guess
    > > that they have the right to be in control of things like that.

    >
    > > Play it safe, guy.

    >
    > > Jeff

    >
    > Not to mention doing something that might disable the entire system.  I
    > have no clue whether that is possible, but you have no right to mess
    > with it.  Let the building management replace it or embroider a pretty
    > doily to cover it up.- Hide quoted text -
    >
    > - Show quoted text -


    Yes if it is a building supplied system you should not mess with it,
    its not yours, its under the owners controll and you could trigger an
    event you dont want. So it old looking , so what.
    ransley, Apr 2, 2008
    #4
  5. Guest

    The unit is a line voltage unit, not low voltage. The smoke detector
    is stand-alone and does not signal back to a building-wide alarm
    system. And the new detector is compatible with the old one.

    Someone mentioned that I should use a special screwdriver. Where can
    I find something like this and what does it look like?

    So as long as I don't touch two of the same wires at the same time,
    I'll be OK? How can I not ground myself? If I'm on a ladder wearing
    rubber-soled sneakers, would that take care of it?

    On Apr 1, 7:59 pm, Jeff Wisnia <> wrote:
    > wrote:
    > > I have a hardwired smoke detector that is old and outdated, that I'd
    > > like to switch with a new unit.  The only problem is that I can't
    > > shut
    > > off the power to the alarm before I disconnect it and reconnect the
    > > new one.  I'm going to have to do the take-down and installation
    > > while
    > > the power is LIVE.

    >
    > > I live in a high-rise apartment building and the smoke detector is
    > > powered not by my unit's individual power, but off of a line brought
    > > in from a common hallway.  There is no way to cut power to the smoke
    > > detector without cutting power to all the lights in the common
    > > hallway, which is impossible.

    >
    > > So, how can I safely (or as safely as possible) change this detector
    > > with a new one?  If I don't touch certain wires together, will I be
    > > OK?  What are the chances I would get shocked?

    >
    > > I know your first inclination will be to tell me to get the circuit
    > > turned off or call an electrician, but please (at least
    > > hypothetically) assume that neither of those options are possible.

    >
    > Do you know if your smoke detector is "powered" by a 120 volt AC line or
    > by a low voltage line?
    >
    > Do you know if the smoke detector sends a signal back to an alarm panel
    > to notify an alarm company that it's been tripped, or does it just sound
    > off in your place?
    >
    > Do you know whether your "new" detector will be electrically and
    > operationally compatible with the existing system(s) in all respects?
    >
    > If you aren't certain about all the above, stay away from that job.
    >
    > Further, I'd suggest you'd be much better off taking the matter up with
    > the apartment building's management (if you haven't already) before you
    > do anything to the existing detector. I'd hazard a guess that they have
    > the right to be in control of things like that.
    >
    > Play it safe, guy.
    >
    > Jeff
    >
    > --
    > Jeffry Wisnia
    > (W1BSV + Brass Rat '57 EE)
    > The speed of light is 1.8*10^12 furlongs per fortnight.- Hide quoted text -
    >
    > - Show quoted text -
    , Apr 2, 2008
    #5
  6. Mike Dobony Guest

    On Tue, 1 Apr 2008 17:22:31 -0700, Frank wrote:

    > Someone mentioned that I should use a special screwdriver. Where can
    > I find something like this and what does it look like?
    >
    > So as long as I don't touch two of the same wires at the same time,
    > I'll be OK? How can I not ground myself? If I'm on a ladder wearing
    > rubber-soled sneakers, would that take care of it?
    >
    > -----------------------------------------------------------------------
    >
    >
    > Looks like you have to do this anyway so here are some advice.
    >
    > 1 Work with a buddy so he/she could call 911 and get help.
    >
    > 2 Use non conducting ladder. Ware electrical insulating gloves and shoes.
    >
    > 3 Don't need special screwdriver, wrap conducting part with electrical
    > tape.
    >
    > 4 Work with one hand only, put the other hand in your back pocket.
    >
    >
    > Remember it doesn't take much, as little as 6 milliamps, to go into
    > ventricular fibrillation or cardiac arrest.



    The key is to not let the current go across the heart. I just did some
    wiring and forgot the outlet next to the switch was live and on another
    circuit. I touched it and held for about a second before I realized what
    was happening. Work with 120 enough and it barely fazes you. I don't
    worry too much about 120 and occasionally work with live wires. You bigger
    concerns are compatibility with the existing system, likely interwired so
    that when one goes off they all go off, and also with not destroying the
    rest of the system. I seriously doubt it is connected to the lighting
    system as the smoke alarms are supposed to be on their own breaker.
    Mike Dobony, Apr 2, 2008
    #6
  7. Terry Guest

    On Tue, 1 Apr 2008 15:32:00 -0700 (PDT), wrote:

    >I have a hardwired smoke detector that is old and outdated, that I'd
    >like to switch with a new unit. The only problem is that I can't
    >shut
    >off the power to the alarm before I disconnect it and reconnect the
    >new one. I'm going to have to do the take-down and installation
    >while
    >the power is LIVE.
    >
    >I live in a high-rise apartment building and the smoke detector is
    >powered not by my unit's individual power, but off of a line brought
    >in from a common hallway. There is no way to cut power to the smoke
    >detector without cutting power to all the lights in the common
    >hallway, which is impossible.
    >
    >
    >So, how can I safely (or as safely as possible) change this detector
    >with a new one? If I don't touch certain wires together, will I be
    >OK? What are the chances I would get shocked?
    >
    >
    >I know your first inclination will be to tell me to get the circuit
    >turned off or call an electrician, but please (at least
    >hypothetically) assume that neither of those options are possible.



    The way you do it safely is to turn the power off.
    Anyone that tells you "It can't be turned off" is lying
    Terry, Apr 2, 2008
    #7
  8. Nate Nagel Guest

    Mike Dobony wrote:
    > On Tue, 1 Apr 2008 17:22:31 -0700, Frank wrote:
    >
    >
    >>Someone mentioned that I should use a special screwdriver. Where can
    >>I find something like this and what does it look like?
    >>
    >>So as long as I don't touch two of the same wires at the same time,
    >>I'll be OK? How can I not ground myself? If I'm on a ladder wearing
    >>rubber-soled sneakers, would that take care of it?
    >>
    >>-----------------------------------------------------------------------
    >>
    >>
    >>Looks like you have to do this anyway so here are some advice.
    >>
    >>1 Work with a buddy so he/she could call 911 and get help.
    >>
    >>2 Use non conducting ladder. Ware electrical insulating gloves and shoes.
    >>
    >>3 Don't need special screwdriver, wrap conducting part with electrical
    >>tape.
    >>
    >>4 Work with one hand only, put the other hand in your back pocket.
    >>
    >>
    >>Remember it doesn't take much, as little as 6 milliamps, to go into
    >>ventricular fibrillation or cardiac arrest.

    >
    >
    >
    > The key is to not let the current go across the heart. I just did some
    > wiring and forgot the outlet next to the switch was live and on another
    > circuit. I touched it and held for about a second before I realized what
    > was happening. Work with 120 enough and it barely fazes you. I don't
    > worry too much about 120 and occasionally work with live wires. You bigger
    > concerns are compatibility with the existing system, likely interwired so
    > that when one goes off they all go off, and also with not destroying the
    > rest of the system. I seriously doubt it is connected to the lighting
    > system as the smoke alarms are supposed to be on their own breaker.


    I've heard it both ways; makes more sense to me to go ahead and put it
    on the lighting circuit, reason being that the homeowner will notice if
    the lights aren't working but if the breaker dedicated to a run of
    detectors trips he may not notice that and be unprotected.

    Of course, the local AHJ has the final word on what's cool and what isn't.

    nate

    --
    replace "roosters" with "cox" to reply.
    http://members.cox.net/njnagel
    Nate Nagel, Apr 2, 2008
    #8
  9. Tony Hwang Guest

    Nate Nagel wrote:

    > Mike Dobony wrote:
    >
    >> On Tue, 1 Apr 2008 17:22:31 -0700, Frank wrote:
    >>
    >>
    >>> Someone mentioned that I should use a special screwdriver. Where can
    >>> I find something like this and what does it look like?
    >>>
    >>> So as long as I don't touch two of the same wires at the same time,
    >>> I'll be OK? How can I not ground myself? If I'm on a ladder wearing
    >>> rubber-soled sneakers, would that take care of it?
    >>>
    >>> -----------------------------------------------------------------------
    >>>
    >>>
    >>> Looks like you have to do this anyway so here are some advice.
    >>>
    >>> 1 Work with a buddy so he/she could call 911 and get help.
    >>>
    >>> 2 Use non conducting ladder. Ware electrical insulating gloves and
    >>> shoes.
    >>>
    >>> 3 Don't need special screwdriver, wrap conducting part with
    >>> electrical tape.
    >>>
    >>> 4 Work with one hand only, put the other hand in your back pocket.
    >>>
    >>>
    >>> Remember it doesn't take much, as little as 6 milliamps, to go into
    >>> ventricular fibrillation or cardiac arrest.

    >>
    >>
    >>
    >>
    >> The key is to not let the current go across the heart. I just did some
    >> wiring and forgot the outlet next to the switch was live and on another
    >> circuit. I touched it and held for about a second before I realized what
    >> was happening. Work with 120 enough and it barely fazes you. I don't
    >> worry too much about 120 and occasionally work with live wires. You
    >> bigger
    >> concerns are compatibility with the existing system, likely interwired so
    >> that when one goes off they all go off, and also with not destroying the
    >> rest of the system. I seriously doubt it is connected to the lighting
    >> system as the smoke alarms are supposed to be on their own breaker.

    >
    >
    > I've heard it both ways; makes more sense to me to go ahead and put it
    > on the lighting circuit, reason being that the homeowner will notice if
    > the lights aren't working but if the breaker dedicated to a run of
    > detectors trips he may not notice that and be unprotected.
    >
    > Of course, the local AHJ has the final word on what's cool and what isn't.
    >
    > nate
    >

    Remember without ground path urrent can't flow. Wear rubber sole shoes.
    Only touch one wire at a time. Don'r make your body a current path.
    I often work on live 120 or 220V lines. As long as this is kept in mind,
    it is OK. More is needed? Wear a pair of thin rubber gloves. Or use a
    tool with insulated grip.
    Tony Hwang, Apr 2, 2008
    #9
  10. Guest

    On Apr 1, 6:29 pm, Mike Dobony <> wrote:
    > On Tue, 1 Apr 2008 17:22:31 -0700, Frank wrote:
    > > Someone mentioned that I should use a special screwdriver. Where can
    > > I find something like this and what does it look like?

    >
    > > So as long as I don't touch two of the same wires at the same time,
    > > I'll be OK? How can I not ground myself? If I'm on a ladder wearing
    > > rubber-soled sneakers, would that take care of it?

    >
    > > -----------------------------------------------------------------------

    >
    > > Looks like you have to do this anyway so here are some advice.

    >
    > > 1 Work with a buddy so he/she could call 911 and get help.

    >
    > > 2 Use non conducting ladder. Ware electrical insulating gloves and shoes.

    >
    > > 3 Don't need special screwdriver, wrap conducting part with electrical
    > > tape.

    >
    > > 4 Work with one hand only, put the other hand in your back pocket.

    >
    > > Remember it doesn't take much, as little as 6 milliamps, to go into
    > > ventricular fibrillation or cardiac arrest.

    >
    > The key is to not let the current go across the heart. I just did some
    > wiring and forgot the outlet next to the switch was live and on another
    > circuit. I touched it and held for about a second before I realized what
    > was happening. Work with 120 enough and it barely fazes you. I don't
    > worry too much about 120 and occasionally work with live wires. You bigger
    > concerns are compatibility with the existing system, likely interwired so
    > that when one goes off they all go off, and also with not destroying the
    > rest of the system. I seriously doubt it is connected to the lighting
    > system as the smoke alarms are supposed to be on their own breaker.


    If by "barely fazes you", you mean it's less likely to hurt you, well,
    yer nuts.
    You've just been lucky so far.

    The OP probably shouldn't be doing this. The setup doesn't make
    sense, and he doesn't know enough to be playing with live wires.
    , Apr 2, 2008
    #10
  11. Mike Dobony Guest

    On Tue, 01 Apr 2008 23:00:58 -0400, Nate Nagel wrote:

    > Mike Dobony wrote:
    >> On Tue, 1 Apr 2008 17:22:31 -0700, Frank wrote:
    >>
    >>
    >>>Someone mentioned that I should use a special screwdriver. Where can
    >>>I find something like this and what does it look like?
    >>>
    >>>So as long as I don't touch two of the same wires at the same time,
    >>>I'll be OK? How can I not ground myself? If I'm on a ladder wearing
    >>>rubber-soled sneakers, would that take care of it?
    >>>
    >>>-----------------------------------------------------------------------
    >>>
    >>>
    >>>Looks like you have to do this anyway so here are some advice.
    >>>
    >>>1 Work with a buddy so he/she could call 911 and get help.
    >>>
    >>>2 Use non conducting ladder. Ware electrical insulating gloves and shoes.
    >>>
    >>>3 Don't need special screwdriver, wrap conducting part with electrical
    >>>tape.
    >>>
    >>>4 Work with one hand only, put the other hand in your back pocket.
    >>>
    >>>
    >>>Remember it doesn't take much, as little as 6 milliamps, to go into
    >>>ventricular fibrillation or cardiac arrest.

    >>
    >>
    >>
    >> The key is to not let the current go across the heart. I just did some
    >> wiring and forgot the outlet next to the switch was live and on another
    >> circuit. I touched it and held for about a second before I realized what
    >> was happening. Work with 120 enough and it barely fazes you. I don't
    >> worry too much about 120 and occasionally work with live wires. You bigger
    >> concerns are compatibility with the existing system, likely interwired so
    >> that when one goes off they all go off, and also with not destroying the
    >> rest of the system. I seriously doubt it is connected to the lighting
    >> system as the smoke alarms are supposed to be on their own breaker.

    >
    > I've heard it both ways; makes more sense to me to go ahead and put it
    > on the lighting circuit, reason being that the homeowner will notice if
    > the lights aren't working but if the breaker dedicated to a run of
    > detectors trips he may not notice that and be unprotected.
    >
    > Of course, the local AHJ has the final word on what's cool and what isn't.
    >
    > nate


    That is assuming that they don't have a battery backup (never seen such an
    animal) and that you are dealing with a homeowner, not a commercial
    apartment complex, as in the OP's case.
    Mike Dobony, Apr 3, 2008
    #11
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