Using low energy light bulbs with timer switches
Anne Morrison
mean is, the switch replaces the normal light switch on the wall, and you
can set it to come on at various times to give the impression that you're
at home (Confession time here - I saw these in the Argos catalogue). I
quite fancy this for my hallway (I have a hideous imitation brass switch
that I want to replace with white plastic anyway). The thing is, I've got
a couple of low energy light bulbs in my hallway. They're Phillips, 17W (I
think - certainly close to that), SL (I think - I checked last night but
have got confused reading the thread on these bulbs), Comfort
(definitely). They're elongated things enclosed in smooth white glass and
cost about 6 quid from B&Q. I seem to remember that the packaging may have
said "not suitable for use with dimmer switches or electronic switches".
But maybe this advice applied to some of the other low energy bulbs?
Anyway, my question is: Can I use said timer switch with my light bulbs?
If not, why not?
Cheers, Anne.
--
Anne I. Morrison --------------- email: Anne.M...@soc.soton.ac.uk
RSADU (Remote Sensing Applications Development Unit)
Rm 254/35, Southampton Oceanography Centre, fax: +44 (0)1703 596400
Empress Dock, SOUTHAMPTON, SO14 3ZH, UK. phone: +44 (0)1703 596411
Blighe
Morrison <Anne.M...@soc.soton.ac.uk> writes
>Hi. I've seen some timer switches for use with overhead lights. What I
>mean is, the switch replaces the normal light switch on the wall, and you
>can set it to come on at various times to give the impression that you're
>at home (Confession time here - I saw these in the Argos catalogue). I
>quite fancy this for my hallway (I have a hideous imitation brass switch
>that I want to replace with white plastic anyway). The thing is, I've got
>a couple of low energy light bulbs in my hallway. They're Phillips, 17W (I
>think - certainly close to that), SL (I think - I checked last night but
>have got confused reading the thread on these bulbs), Comfort
>(definitely). They're elongated things enclosed in smooth white glass and
>cost about 6 quid from B&Q. I seem to remember that the packaging may have
>said "not suitable for use with dimmer switches or electronic switches".
>But maybe this advice applied to some of the other low energy bulbs?
>
>Anyway, my question is: Can I use said timer switch with my light bulbs?
>If not, why not?
>
>Cheers, Anne.
>
None of the Philips Energy Saver bulbs can be used with true
"electronic" switches unfortunately (this means the PL Electronic,
SL Comfort/Prismatic and SL Decor/PL Electronic D).
However, some so-called electronic switches are OK!
Some switches use a relay internally to switch on the power
and these are ok to use with an energy saver bulb. The true
solid state electronic switches use a TRIAC to switch on the
power and should NOT be used to control energy saver bulbs.
How can you tell what type of switch you have?
Switch it on and off and listen. If it contains a relay you
will hear a click as it switches. If it is silent it is
TRIAC controlled.
I have used something similar the type of security device which replaces
the light switch that you mention (made by Smiths I think). This came on
after dark for a preset duration. The bad news is that they are TRIAC
controlled and not suitable for energy saver bulbs. (Looking in the
Argos catalogue I see item 431/0624 which is definitely not suitable
as it says "not suitable for fluorescent lighting").
To answer the final part of your question "if not, why not?" is
difficult unless you are an Electrical/Electronic Engineer (like me!)
but (very roughly) it is probably due to the TRIAC distorting the
mains supply slightly and upsetting the high frequency inverter which
drives the fluorescent tube/bulb.
Regards
Jeremy
Leo Hendry
Anne Morrison <Anne.M...@soc.soton.ac.uk> wrote:
>Anyway, my question is: Can I use said timer switch with my light bulbs?
>If not, why not?
If you can hear a click when it switches then yes, otherwise you may
break the timer. The timer should say if it won't work with low energy
light bulbs, but if it doesn't and it breaks then take it back.
- Leo
Matthew Marks
: In article <Anne.Morrison-2...@139.166.172.25>,
I think the actual reason is that many timers don't require a neutral
connection (because they are designed to replace light switches), and hence
pass a low current even when their output is not activated in order to keep
going. This has no effect on an ordinary light bulb, but will charge the
smoothing cap. in an electronic low-energy type until the oscillator starts,
thus causing the lamp to flash briefly at intervals. It has been suggested
that if two lamps are being switched, one of them should be an incandescent
type to overcome this problem (and I guess that the non-electronic low energy
types would work too). A triac controlled timer should not break when
switching a low energy lamp, as it is designed to cope with the current surge
from an incandescent lamp anyway.
Matthew mat...@rd.bbc.co.uk My opinions, not Auntie's.
:
: - Leo
Derek G. Geldard
Anne.M...@soc.soton.ac.uk "Anne Morrison" writes:
>
> Anyway, my question is: Can I use said timer switch with my light bulbs?
> If not, why not?
Anne, I think not without some hassle.
Reason, Most light switches are 2-wire devices in series with the
bulb. Usually the neutral is not even wired into the box. To obtain
the tiny amount of power they need to run their electronics electronic
switches use a trick of circuitry which relies on the presence of a
current path to neutral through the bulb even when it's off. Miniature
flourescents can not be relied upon to draw enough current in the off state
to keep the electronic clock running. One way round it would be to keep one
filament lamp in the circuit (a small one) and wire the flourescent lamps
in parallel with it. Alternatively wire 1 or more resistors across the
fluorescent lamp, 100k 1 watt might do, bear in mind that the resistors
will get hot, this worked for me once.
Derek
--
Derek G. Geldard
Anne Morrison
I guess that if I want to use one of these switch timers I need to change
my bulbs...
Matthew Marks
: Miniature
: flourescents can not be relied upon to draw enough current in the off state
: to keep the electronic clock running.
Ah - that sounds more plausible than my explanation that the light will
flicker. Ignore that bit of my posting. :-)
Andrew Gabriel
mat...@rd.bbc.co.uk (Matthew Marks) writes:
>
> A triac controlled timer should not break when
> switching a low energy lamp, as it is designed to cope with the current surge
> from an incandescent lamp anyway.
It probably won't be designed to cope with the back-emf from the inductor
of a switch-start fluoresent lamp, as used in the older heavier compact
fluoresents. A possible failure mode of the triac is a short in one
direction only, supplying the switch-start fluoresent lamp with DC, which
I suspect would make it overheat and/or the tube explode!
The electronic ones don't have this problem, and as others have suggested,
would probably work OK if at least one filament lamp is used too.
However, their Current waveform is rather nasty, so I would make sure
the load is much less than the maximum rated [filamant lamp] loading of
the switch.
--
Andrew Gabriel Home: And...@cucumber.demon.co.uk
Consultant Software Engineer Work: Andrew....@net-tel.co.uk
John E. Fox
>Anyway, my question is: Can I use said timer switch with my light bulbs?
>If not, why not?
>
>Cheers, Anne.
>
If the switch is a simple mechanical relay, then they will be OK.
Have seen the said devices in B&Q but am not sure what type of relay they
use.
John Fox
Ed Sirett
writes:
>>Anyway, my question is: Can I use said timer switch with my light bulbs?
>>If not, why not?
>>
>>Cheers, Anne.
>>
light with an older style energy-saving bulb (the sort that take a minute
or two to get to full brightness). The said bulb lasted about 2 weeks
although the timer worked OK. Of course this could have been just bad
luck...
Education is expensive... but cheap in contrast to ignorance.
>-------------------------------------------------------------------------
Ed Sirett, Computer consultant and Property Repairer.
Tel: 0181 883 1448 Fax: 0181 444 7740
-------------------------------------------------------------------------
John Shotton
Anne.M...@soc.soton.ac.uk (Anne Morrison) wrote:
> Hi. I've seen some timer switches for use with overhead lights. What I
> mean is, the switch replaces the normal light switch on the wall, and you
> can set it to come on at various times to give the impression that you're
> at home (Confession time here - I saw these in the Argos catalogue). I
> quite fancy this for my hallway (I have a hideous imitation brass switch
> that I want to replace with white plastic anyway). The thing is, I've got
> a couple of low energy light bulbs in my hallway. They're Phillips, 17W (I
> think - certainly close to that), SL (I think - I checked last night but
> have got confused reading the thread on these bulbs), Comfort
> (definitely). They're elongated things enclosed in smooth white glass and
> cost about 6 quid from B&Q. I seem to remember that the packaging may have
> said "not suitable for use with dimmer switches or electronic switches".
> But maybe this advice applied to some of the other low energy bulbs?
>
> Anyway, my question is: Can I use said timer switch with my light bulbs?
> If not, why not?
>
> Cheers, Anne.
My description for the lamps you describe is "jam jar fluorescent"
No you cannot use an electronic timer which replaces a normal light
switch. The timer gets its own electricity supply in series with the load,
i.e. the lamps. When it switches the lamps off, it will continue to pass a
very small amount of current through them to meet its own needs. No type
of fluorescent lamp will pass such a small current as the tube itself is
either on or off.
There may also be a problem with the jam jar Phillips types as these use
an inductive ballast which produces a voltage kick on switch off.
You may be ok if you include one normal bulb. This will allow the small
current drain to maintain the supply to the timer when the lamps are off
and it will also absorb the voltage spike. To keep the voltage spike to
less than mains value the wattage of the normal lamp should be twice or
greater than that of the combined wattages of all the fluorescent lamps on
the same circuit.
For the technical, the factor of two I've used above assumes that the
power factor of an inductive fed fluorescent is 0.5, i.e. the current is
twice that given from P=VxI.
--
John Shotton