Strange problem with low energy light bulb

[Seán O'Leathlóbhair]

I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.

When it is switched off, it blinks every few seconds. So, I guess
that there must be a problem with the switch If it is passing nothing
then it would seem impossible for the bulb to do anything. I did not
notice any problem with the previous incandescent bulb but I guess
that if the switch is leaking a tiny amount, the filament would glow
too little to be seen.

I have a few questions:

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

Is it safe?

Will it wear out the bulb very fast?

Is it likely to be enough to replace the switch? (Actually three
switches can turn this bulb on and off).

Might I have to replace the wiring? (Much harder than just replacing
the switches)

 

[N Cook]

I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.

When it is switched off, it blinks every few seconds. So, I guess
that there must be a problem with the switch If it is passing nothing
then it would seem impossible for the bulb to do anything. I did not
notice any problem with the previous incandescent bulb but I guess
that if the switch is leaking a tiny amount, the filament would glow
too little to be seen.

I have a few questions:

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

Is it safe?

Will it wear out the bulb very fast?

Is it likely to be enough to replace the switch? (Actually three
switches can turn this bulb on and off).

Might I have to replace the wiring? (Much harder than just replacing
the switches)

--
Seán Ó Leathlóbhair


It may not be a switch problem but more seriously an animal , usually
squirrel or mouse or rat has chewed the insulation along the wires going to
the switch, now with charred insulation, so passing a bit of current - so
get the wiring leakage/visually checked. Especially if you've had any
unexplained fuses blowing or history of animal noises in loft or floor
spaces.

 

[BH]

I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.

When it is switched off, it blinks every few seconds. So, I guess
that there must be a problem with the switch If it is passing nothing
then it would seem impossible for the bulb to do anything. I did not
notice any problem with the previous incandescent bulb but I guess
that if the switch is leaking a tiny amount, the filament would glow
too little to be seen.

I have a few questions:

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

Is it safe?

Will it wear out the bulb very fast?

Is it likely to be enough to replace the switch? (Actually three
switches can turn this bulb on and off).

Might I have to replace the wiring? (Much harder than just replacing
the switches)

Try the buld in another location. Give us moe information on the bulb.

Bruce

 

[Seán O'Leathlóbhair]

Try the buld in another location. Give us moe information on the bulb.

Thanks.

Normally, I would immediately try to isolate the cause by moving
things around but, in this case, I dismissed the bulb as the problem
since I thought that if the switch was passing nothing when off (as it
should) then there was no way the bulb could do what it is doing. If
the bulb is at fault then it is not the only fault (or so I assumed at
any rate).

The brand of the bulb is Philips but I cannot tell you more until I
get home and look at it. I will post again later with fuller details
and the result of a test in another location.

 

[Seán O'Leathlóbhair]

I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.

When it is switched off, it blinks every few seconds. So, I guess
that there must be a problem with the switch If it is passing nothing
then it would seem impossible for the bulb to do anything. I did not
notice any problem with the previous incandescent bulb but I guess
that if the switch is leaking a tiny amount, the filament would glow
too little to be seen.

I have a few questions:

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

Is it safe?

Will it wear out the bulb very fast?

Is it likely to be enough to replace the switch? (Actually three
switches can turn this bulb on and off).

Might I have to replace the wiring? (Much harder than just replacing
the switches)

--
Seán Ó Leathlóbhair

It may not be a switch problem but more seriously an animal , usually
squirrel or mouse or rat has chewed the insulation along the wires going to
the switch, now with charred insulation, so passing a bit of current - so
get the wiring leakage/visually checked. Especially if you've had any
unexplained fuses blowing or history of animal noises in loft or floor
spaces.

Thanks for the advice.

We had some fuse problems many years ago but not on the lighting
circuits. The problem was traced (by a proper electrician) to the
ancient (bakelite) fuse box. It was replaced with a modern fuse box.
The wiring was tested (but not completely inspected) at the time.
Since then, we have not had any fuse problems. That was about 10
years ago.

I am not aware of any animal problems in the loft but, of course, that
does not mean that there have not been any. Access to the loft is
difficult since it is very small but not quite impossible. I will
squeeze myself in and have a look.

 

[Ken Weitzel]

Thanks.

Normally, I would immediately try to isolate the cause by moving
things around but, in this case, I dismissed the bulb as the problem
since I thought that if the switch was passing nothing when off (as it
should) then there was no way the bulb could do what it is doing. If
the bulb is at fault then it is not the only fault (or so I assumed at
any rate).

The brand of the bulb is Philips but I cannot tell you more until I
get home and look at it. I will post again later with fuller details
and the result of a test in another location.

Hi...

Can't help wondering - it's not possible that one of those
"switches" is a dimmer, is it?

Take care.

Ken

 

[Seán O'Leathlóbhair]

Hi...

Can't help wondering - it's not possible that one of those
"switches" is a dimmer, is it?

Take care.

A good question but no.

It is a landing light. There are three switches, one at each end and
a third in the middle where a small corridor from the bathroom joins
the landing. All simple on off switches (well they must be changeover
switches but, from the user's point of view, they are just on off).

 

[Ron(UK)]

A good question but no.

It is a landing light. There are three switches, one at each end and
a third in the middle where a small corridor from the bathroom joins
the landing. All simple on off switches (well they must be changeover
switches but, from the user's point of view, they are just on off).

Sounds like leakage to me, there may be a measurable voltage floating on
the neutral. I has a similar problem with fluorescent emergency lights
last year. If you are in the UK it might be an earthing fault.

Ron(UK)

 

[Seán O'Leathlóbhair]

Sounds like leakage to me, there may be a measurable voltage floating on
the neutral. I has a similar problem with fluorescent emergency lights
last year. If you are in the UK it might be an earthing fault.

I am in the UK.

How does an earthing fault affect the lighting circuit? I thought it
was just two wire. The earthing for the house in general was checked
a couple of years ago when we changed the boiler. The gas engineer
said that a change was required but I forget exactly what that was.
The RCCB in the new fuse box is not tripping but does it apply to the
lighting circuits?

 

[Scalp]

Hi, this isn;t that uncommon a problem with low energy bulbs. Its
probable that there is a voltage induced into the 'dead' circuit by
cables running in close proximity to one another. Typically this
occurs on long cable runs for hall/landing circuits.
The way I'd bottom it is to use a DVM across the lamp socket & see
what voltage is present. You shouldn't be able to draw any current (to
speak of) from a capacitive or inductive coupling.
What happens is that theres enough voltage for the tube to strike but
no capacity to draw current, so it goes out until the voltage builds
up again.
You can buy suppression capacitors to overcome this (Note they are
special devices - don't try to bodge it!) but sometimes just swapping
with another LE bulb will do the trick.
If the problem isn't as described, you'd better get someone in to
check the wiring for contacts or earth problems.
Dale.

 

[Yukio YANO]

I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.


I have a few questions:

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

Is it safe?

Will it wear out the bulb very fast?

Is it likely to be enough to replace the switch? (Actually three
switches can turn this bulb on and off).

Might I have to replace the wiring? (Much harder than just replacing
the switches)

On a cold wet miserable winter day in the early 70's. I was
troubleshooting a newish car, that wouldn't start, that had just been
serviced by a car dealership. a few days before. To cut a long story
short, they lubricated the Point Breaker mechanism with a clear Grease
that they probably used for years with no problems ! With 2 to 6 Amps
flowing, the contact mechanism probably cooked off any wet or
conductive grease. With the newer Hybrid Transistor switched points the
DAMP grease appeared as a Dead Short to the few milliamps required to
actuate the Transistor.

I would suspect the switches (All three) are lubricated with a grease
that is conductive enough read (dirty enough)to cause the problems
indicated !

The quick and dirty, to clear the excess grease is to replace the lamp
in question with a 60 - 100 watt bulb and switch On and Off a few
times. in the Off position any conductive grease will be burned away.

Any fire Hazard, Not likely, after all these switches were manufactured
and sold for years lubricated just like this, besides we are talking
about a drop or two grease total ! If you are worried, replace the
switches.

If this doesn't clear the problem than you may have exessive
capacitative coupling between the various conductors due to the
three-way switching, under a very light load !

Yukio YANO

 

[Eeyore]

I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.

When it is switched off, it blinks every few seconds.

In order to do that it must be getting power from somewhere. You must have a
fault in the switch or related wiring.

Graham

 

[Eeyore]

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

That would appear to be the case.

Graham

 

[Eeyore]

Hi, this isn;t that uncommon a problem with low energy bulbs. Its
probable that there is a voltage induced into the 'dead' circuit by
cables running in close proximity to one another. Typically this
occurs on long cable runs for hall/landing circuits.

How is this voltage induced ? Are you suggesting electromagnetic coupling ? That
sounds astonishingly unlikely.

Graham

 

[Ron(UK)]

I am in the UK.

How does an earthing fault affect the lighting circuit? I thought it
was just two wire. The earthing for the house in general was checked
a couple of years ago when we changed the boiler. The gas engineer
said that a change was required but I forget exactly what that was.
The RCCB in the new fuse box is not tripping but does it apply to the
lighting circuits?

If the neutral wire isn't properly grounded enough voltage can be
induced by or leak from other 'live' circuits, maybe enough to cause the
fluorescent fittings to randomly flicker. It could be a faulty switch
leaking across the contacts.

You don't live beneath an electricity pylon do you? It might also be
the rays from guvmint mind control experiments entering your house.

Ron(UK)

 

[PeterD]

A good question but no.

It is a landing light. There are three switches, one at each end and
a third in the middle where a small corridor from the bathroom joins
the landing. All simple on off switches (well they must be changeover
switches but, from the user's point of view, they are just on off).

Your switches are wired wrong (they are switching the neutral (or
cold) side of the line, not the hot side. As well, you seem to have a
leakage problem in the circuit as well. This leakage could be a switch
or some other device or part.

First step is to make 100% sure the switches are in the hot side of
the circuit. That will likely solve your problem immediately. I'd
guess there is a chance much of your house is not wired correctly from
your description...

Not sure what building codes/wriing codes you have in the UK, but in
the US this circuit would not have passed a building inspector.

 

[Eeyore]

If the neutral wire isn't properly grounded enough voltage can be
induced by or leak from other 'live' circuits, maybe enough to cause the
fluorescent fittings to randomly flicker.

Ron, when the switch is off, there is no circuit. The neutral potential
literally doesn't matter.

Graham

 

[Eeyore]

Your switches are wired wrong (they are switching the neutral (or
cold) side of the line, not the hot side.

Makes no difference. When the switch is off, the circuit is broken.

Graham

 

[Meat Plow]

I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.

When it is switched off, it blinks every few seconds. So, I guess
that there must be a problem with the switch If it is passing nothing
then it would seem impossible for the bulb to do anything. I did not
notice any problem with the previous incandescent bulb but I guess
that if the switch is leaking a tiny amount, the filament would glow
too little to be seen.

I have a few questions:

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

Is it safe?

Will it wear out the bulb very fast?

Is it likely to be enough to replace the switch? (Actually three
switches can turn this bulb on and off).

Might I have to replace the wiring? (Much harder than just replacing
the switches)

--
Seán Ó Leathlóbhair


It may not be a switch problem but more seriously an animal , usually
squirrel or mouse or rat has chewed the insulation along the wires going to
the switch, now with charred insulation, so passing a bit of current - so
get the wiring leakage/visually checked. Especially if you've had any
unexplained fuses blowing or history of animal noises in loft or floor
spaces.

Could you fix your news reader so it correctly quotes and attributes the
previous post?

 

[Sjouke Burry]

Ron, when the switch is off, there is no circuit. The neutral potential
literally doesn't matter.

Graham

Capacitive leakage from the HOT wire to the switch
wire? That could trickle charge and cause an
occasional flicker.
Random spikes would leak through much easier, and
cause random flicker.
Try as cure a small capacitor (100NF)across the
lamp terminals, just as long as the cap is much
bigger than the parasite one.