Re: OT: Extension lead safety

Discussion in 'NZ Computing' started by Nicolaas Hawkins, Aug 23, 2009.

  1. On Sun, 23 Aug 2009 19:00:40 +1200, ofn01 <> wrote in
    <news:4a90e9f3$>:

    > Is it ok to plug a 2400W heater into the wall socket through one of these?
    >
    > http://www.dse.co.nz/dse.shop/en/product/M7552


    No. Absolutely not.

    The extension cord in question is rated at 10 Amps.

    A 2400W heater draws 2400/230 (watts/volts) = 10.434 Amps.

    You would be drawing more current through the extension cord than it is
    rated for. It will heat up and will likely cause a fire.

    To run a heater of that wattage with any degree of safety you would need to
    use an extension cord rated at _at least_ 15 Amps - and even then, with
    care.

    It is far safer NOT to feed a heater via an extension cord at all.


    --
    - Nicolaas
    Nicolaas Hawkins, Aug 23, 2009
    #1
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  2. Nicolaas Hawkins

    greg Guest

    Nicolaas Hawkins wrote:
    > On Sun, 23 Aug 2009 19:00:40 +1200, ofn01 <> wrote in
    > <news:4a90e9f3$>:
    >
    >> Is it ok to plug a 2400W heater into the wall socket through one of these?
    >>
    >> http://www.dse.co.nz/dse.shop/en/product/M7552

    >
    > No. Absolutely not.
    >
    > The extension cord in question is rated at 10 Amps.
    >
    > A 2400W heater draws 2400/230 (watts/volts) = 10.434 Amps.
    >
    > You would be drawing more current through the extension cord than it is
    > rated for. It will heat up and will likely cause a fire.
    >
    > To run a heater of that wattage with any degree of safety you would need to
    > use an extension cord rated at _at least_ 15 Amps - and even then, with
    > care.
    >
    > It is far safer NOT to feed a heater via an extension cord at all.
    >
    >



    Try buying off the shelf a 15A extension cord with the suitable 15A plug
    and socket each end, now try to find a domestic outlet to plug it in to.


    Personally, I wouldn't worry about it, the cord will get warm, but will
    work within specifications.
    greg, Aug 23, 2009
    #2
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  3. Nicolaas Hawkins

    Carnations Guest

    On Sun, 23 Aug 2009 19:50:51 +1200, Nicolaas Hawkins wrote:

    > A 2400W heater draws 2400/230 (watts/volts) = 10.434 Amps.


    A 2400W heater draws 10A at 240V.

    That extn cord is rated at 10A x 240V.


    --
    "Filtering the Internet is like trying to boil the ocean"
    Carnations, Aug 23, 2009
    #3
  4. Nicolaas Hawkins

    Richard Guest

    Nicolaas Hawkins wrote:
    > On Sun, 23 Aug 2009 19:00:40 +1200, ofn01 <> wrote in
    > <news:4a90e9f3$>:
    >
    >> Is it ok to plug a 2400W heater into the wall socket through one of these?
    >>
    >> http://www.dse.co.nz/dse.shop/en/product/M7552

    >
    > No. Absolutely not.
    >
    > The extension cord in question is rated at 10 Amps.
    >
    > A 2400W heater draws 2400/230 (watts/volts) = 10.434 Amps.
    >
    > You would be drawing more current through the extension cord than it is
    > rated for. It will heat up and will likely cause a fire.


    No, as at 230 volts the heater will be taking about 2200 watts, at 220v
    it drops to 1900and a bit watts. Yes, there is some over currenting at
    250volts, but thats built into the ratings of things at 10 amps. The
    same current carrying pins are used on 15 amp cables anyway so they must
    be good to quite a bit more then 15.

    > To run a heater of that wattage with any degree of safety you would need to
    > use an extension cord rated at _at least_ 15 Amps - and even then, with
    > care.


    I have not seen 1.5mm cable in anything other then long lenghts, with
    transparant plugs and bright yellow for builders. Thats not needed in a
    house at all.

    > It is far safer NOT to feed a heater via an extension cord at all.


    Its far safer not to use one.
    Richard, Aug 23, 2009
    #4
  5. On Sun, 23 Aug 2009 10:43:39 +0000 (UTC), Carnations
    <> wrote in
    <news:p>:

    > On Sun, 23 Aug 2009 19:50:51 +1200, Nicolaas Hawkins wrote:
    >
    >> A 2400W heater draws 2400/230 (watts/volts) = 10.434 Amps.

    >
    > A 2400W heater draws 10A at 240V.
    >
    > That extn cord is rated at 10A x 240V.


    The electrical supply in New Zealand is 230 volts, David, not 240.

    --
    - Nicolaas
    Nicolaas Hawkins, Aug 23, 2009
    #5
  6. Nicolaas Hawkins

    EMB Guest

    Nicolaas Hawkins wrote:
    >
    > The electrical supply in New Zealand is 230 volts, David, not 240.
    >


    As such, if that heater is actually 2400W @ 230V it is illegal to sell
    or use in NZ if it has a standard 10A plug on it.
    EMB, Aug 23, 2009
    #6
  7. Nicolaas Hawkins

    peterwn Guest

    On Aug 23, 7:50 pm, Nicolaas Hawkins <> wrote:
    > On Sun, 23 Aug 2009 19:00:40 +1200, ofn01 <>  wrote in
    > <news:4a90e9f3$>:
    >
    > > Is it ok to plug a 2400W heater into the wall socket through one of these?

    >
    > >http://www.dse.co.nz/dse.shop/en/product/M7552

    >
    > No.  Absolutely not.
    >
    > The extension cord in question is rated at 10 Amps.
    >
    > A 2400W heater draws 2400/230 (watts/volts) = 10.434 Amps.
    >
    > You would be drawing more current through the extension cord than it is
    > rated for.  It will heat up and will likely cause a fire.


    The 10A extension cord rating is a 'nominal' one, the limiting factor
    being the nominal rating of the plug and socket. As pointed out
    elsewhere 1.0sqmm 'fixed' wiring has a 16A 'close protection' (ie MCB
    or HRC fuse) rating. Even the 16A rating is rather conservative.

    A nominal '2400w' heater will run at a nominal 2300w in NZ since NZ
    has a nominal voltage of 230v compared with Australia's 240w (and NZ
    and Australia are effectively a 'common' market for appliances because
    the plugs are the same).

    Therefore the 10A 1.0sqmm lead is quite adequate as long as part of it
    is not coiled up. The heater should be the only appliance run via the
    lead which should be plugged straight into the outlet and not via a
    plug board. A more significant problem IMO is the plugs and sockets
    overheating (especially if old and the springy parts have lost
    tension) than the lead itself overheating - this being a problem
    whether or not an extension lead is used.

    I have not heard of fires etc involving an extension lead used for
    heaters in this manner, nor do I recollect any warnings from
    electrical safety authorities concerning this (apart from not using a
    lead while part is coiled up).

    The main reason to use a 1.5sqmm extension lead is when a long lead is
    required such as for an electric lawn mower, etc. This is because
    the voltage drop on a long 1.0sqmm lead may be excessive. For outdoor
    use a RCD device must be used, and tested before use. If the house has
    RCD's already they should be tested monthly or so, being careful not
    to upset any computer users.

    If the OP still has concerns, then the most conservative solution
    would be to use two 1200w heaters (or 2400w heaters on the 'low'
    setting) with separate leads.
    peterwn, Aug 23, 2009
    #7
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