Very Weird Problem with compact fluorescent bulbs

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Old 09-01-06, 11:09 PM
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Very Weird Problem with compact fluorescent bulbs

Hi,

I have 3 light fixtures controlled by one switch, the breaker that controls that switch is also connected to 2 outlets, where one of the outlets I connect my computer to. The weird part is when I changed all the light bulbs from regular ones to Compact fluorescent bulbs they flicker very dimly when the Switch is OFF, and flicker very fast and bright when the Switch is ON. If I take out one or two bulbs and leave one or two compact fluorescent bulb in it still does the same thing, flicker very dimly when the switch if OFF, but if I put a regular bulb in anyone of the fixtures, then everything works fine, when the switch is off, the all bulbs are off and when the switch is on all the bulbs are on and NO flickering. So, as long as I have one regular light bulb in there everything works fine. Does anyone know why this is happening? coz i want to change all of them to energy saving bulbs. Thanks ...
 
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Old 09-02-06, 04:27 AM
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Could you try a couple things for me. First try the bulbs with the computer unplugged. Next post the mfg name and part number of those CF lamps. I do not know the answer, but you have me curious, I want to do some research.
 
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Old 09-02-06, 05:11 AM
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For when the lamps are off, if I remember correctly, there was a thread here discussing something similar. Someone with more knowledge of the subject than I have thought it was because of the capacitors within the CF's. Depending upon the type of capacitor, some of them have the ability to build their own charge (electrolytic) and the flickering when off was a result of this buildup and discharge. It apparently would eventually stop in that situation.

Now I believe it may be a result of something similar but a bit different. Although the hot to the lights is disconnected, caps are an odd animal. I think what is happening is they are recieving a slight charge due to the neutral and the fact that there is something on the same neutral actually utilizing power (the computer maybe). This would apply a current to the neut and I think it is somehow causing a miniscule current flow in to the cap from this. As the current stops, the cap discharges and flickers the lamp. If the neut has a poor connection and actually allows a potential in the neut compared to ground, this would be the same as an actual applied voltage from a hot leg. A cap will charge and discharge from this, causing a flicker.


Now as to why they flicker when on:
I am not sure but I suspect a poor neutral connect somewhere in this circuit. This would also explain (in my head anyway) the flicker when off situation as well.

The other possibility gets into harmonics but I don't think that would be the sole cause of the flicker.

I believe the incandescent lamp is acting as an inductor that opposes the current the cap would experience and reduces it below a threshold the cap requires to fire the lamps.


Ultimately a neut should always be 0 potential to ground. If there is a poor connection, it can cause a restriction (if you will) of current flow to the nuet bar and cause a potential in that neut. If the CF are in circuit before the resistance (restriction) they would experience a potential on the neutral side of things.

The other much less complex explanation is that the CF's are somewhat defective, either in their design or manufacture and if replaced with a different CF (of other manuf, I would suggest) the problem may go away. Since most of these guys tend to have electronic ballasts, they have very little natural inductance in them and are affected by very minute differences in potential.

I do have a question as well. Is this a multiwire circuit (2 hots to one neutral)? If this is the case, I can see where a poor neut could actually cause a temporary voltage increase ABOVE 120 volts. This may cause the flicker when the lamps are on. Again though, a poor neutral connection would be what I looked for as a fix.
 
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Old 09-02-06, 05:31 AM
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Originally Posted by nap
I believe the incandescent lamp is acting as an inductor that opposes the current the cap would experience and reduces it below a threshold the cap requires to fire the lamps.
I was thinking along the same lines, except that I thought the regular lamp would act as a resistor and bleed off the capacitive voltage, or over voltage.
 
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Old 09-02-06, 07:45 AM
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What type of switch do you have? Is it a dimmer? Is it a lighted switch.
If it is not already try a normal unlighted switch.
 
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Old 09-02-06, 08:49 AM
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my lights are on a normal switch. I've tried it with everything unplugged from the outlets and it's still the same thing, and the type of CF Lamps i'm using are the Philips Daylight (BH342, 22kj e197131) , but i've also tried other it with the regular philips CF Bulbs and it's the same thing. also, i've checked all the connections on the lights, they are all very good.

thanks.
 
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Old 09-02-06, 09:00 AM
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Question, If it was a bad neutral connection wouldn't the lights flicker no matter what kind of bulbs i have in them? ... but it only flickers when all 3 lights have CF lamps, and as long as i have a regular bulb in any one of the fixtures then there is no flickering with the switch on or off. Also, it does the same thing even if I remove one of the fixtures, ... as long as i have one regular bulb everything is fine.
 
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Old 09-02-06, 09:14 AM
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I was speaking of all neutral connections. This would include each joint in every junction box and including the connection at the panel an even the neutral connection to the POCO.

To your last post: a connection is of varying degrees of connection quality and resultant resistance. Depending upon the voltage and current levels, diferent levels of resistance can cause varying effects.

All in all, this is one place to look for a fix.
 
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Old 09-02-06, 10:05 AM
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Leave the switch off with the cf lamps in for an extended time say ten min to an hour and let us know if the problem goes away.
 
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Old 09-02-06, 02:48 PM
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Thanks for you help,

I found what the problem was, It was the remote wireless 3-way switch that was making it flicker, eventhough i don't know why it would do that. Oh well, guess i'll have to try to find a different Wireless 3-way that won't make it do that.
 
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Old 09-03-06, 09:11 AM
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my lights are on a normal switch.
It was the remote wireless 3-way switch that was making it flicker
Two contradicting statements.

The reason they filcker is that the remote switch requires some power to operate it. That power is acquired through the lights on the circuit. It is a minimal current draw that will not light a regular bulb. However it is enough the make the CFLs flicker. The same thing happens with lighted switches. That is why I asked the question.
 
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Old 09-03-06, 01:19 PM
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the funny thing is if all the fixtures have CF lamps why do they still flicker when the switch is ON. or when i have 2 cf lamps and 1 incandescant bulb, shouldn't the 2 CF lamps still flicker?

thanks
 
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Old 03-01-08, 04:36 AM
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I just installed some compact flourescent bulbs and was having the flickering problem also when the light switch was off. The bulb(s) would flicker weakly every 6 seconds or so. If I removed the bulb it would stop, so it was not something internal in a bulb after power was removed e.g a capacitor that was still charged.

I disconnected a light switch in case some current was leaking through somehow but this still continued. I put a multimeter across the bulb and found the voltage would ramp up to about 30VAC at which time the bulb would flicker and the voltage would drop to around 10VAC. This cycle would continue over and over.

I'm not sure if there is a leak somewhere or if this is an induced voltage having other cables running in parallel. The wiring is only a few years old.

What I ended up doing was putting 470K ohm resistors across each bulb (i.e in parallel which each bulb). This stops the voltage from ramping up. It holds the voltage lower than 8VAC. This uses less than 0.13W of power per bulb so it doesn't waste much energy and for me anyway, has fixed this problem.
 
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Old 03-01-08, 07:54 AM
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This thread is 2 years old. Start a your own new thread for your problem.
 
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Old 07-27-08, 09:41 AM
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I have the same strange behavior. I have ceiling light that takes 3 bulbs. If I replace all three bulbs with cf light bulbs the light switch will make a buzz sound when I turn on the light. It does this in three different rooms that have the same built in light fixture. If replace just one of the three cf's with a regular light bulb, then the buzz in the light switch stops. Also, in one case if I had 3 cf's I would get flickering, and when I replaced one with a regular light bulb the flickering went away. Anyone know why this phenomina occurs?
 
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Old 07-27-08, 10:57 AM
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Are any of these fixtures controlled by a dimmer switch?
 
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