Recently, a reader emailed me with a question that stumped me for a bit. He had noticed that fluorescent lights seemed to degrade his wifi signal. I had heard that before but only in passing. His question was a simple “why?”
Ultimately, I ended up talking to an electromagnetics PhD over it. He broke it down into fairly simple terms for me.
As discussed in a previous article, thermionic emission occurs in the lamp portion of a fluorescent light bulb. This occurs as an arc passes through the mercury vapor present in the lamp. One side effect of this is the production of radio waves up to a few megahertz in frequency.
These radio waves are transmitted, often via electrical wires acting as antennas, into the surrounding environment.
Photo credit: La Trobe University
Wifi operates on radio waves at about 2.4 or 5Ghz.
Now I know what you’re thinking because I was thinking the same thing (electromagnetics is my weak point). How does a relatively lower frequency disrupt a much higher frequency signal? Turns out, the relatively weaker Wifi signal will still feel the effects of “cross-talk” from the locally stronger radio waves effecting it. It is possible that the Wifi signal will get picked up as modulation for what is basically a lower frequency carrier wave.
Another much more simple possibility is that destructive interference is happening often enough to cause dropped message packets between the computer and the router. Sure, you wouldn’t expect it to happen that often since the frequencies are mismatched by such a large amount but it doesn’t have to happen often to be a nuisance. Packets get dropped whenever bits are missing based on a checksum test of each packet that arrives. Corrupted data? Your packet gets thrown away. Either way, your Internet experience suffers. Thanks, physics. All possible explanations boil down to different types of electromagnetic interference causing problems with your wifi reception.
For further reading on lighting systems, check out this article on LED lighting.
From one Tyler to another, THANKS! for some time now when my mom goes to bed and has her lamp on and tv (old box tv) my internet would go out. for the longest time I thought it was her old tv emitting some frequency that was disrupting it, but last night my internet came back when she turned her lamp off (tv still on) which really stumped me. tonight same thing happened and sure enough my internet came straight back as soon as the lamp was off. google led me here to end the insanity.
Sorry to hear about your issues but I’m glad you have an answer now!
I also have a real big problem, I have been supplied a new hub and 3 new Hotspot extenders but the problem as follows still exists.
I just realised last night that it appears that it seems that in the evening only, when we use table lamps fitted with the new flurescent plugged into the power sockets, I lose the ethernet connection to the TV and my I Pad.
I think I hit on the problem, and I think you have confirmed it, I will try tonight without the lamps on, thank you.
Regards, unhappy Barry
Hi Barry. Sorry, looks like the spam filter delayed your message getting through. In your post, you said ETHERNET connection. Did you mean WiFi? Your wired ethernet connection is on a totally separate set of wiring from your electrical power system and should have almost no interference as a result of WiFi.
Barry *may* have meant wireless ethernet. 😉
The Wi-Fi Alliance was once known as the Wireless Ethernet Compatibility Alliance. Wi-Fi standards implement/use Ethernet. I think wired/wireless are better qualifiers than ethernet/wireless, ethernet/wi-fi, etc.
I left a message earlier but forgot to enquire if you think the followin has any effect. My Hub was set up for my TV which is in another room, for 2.4GHz instead of the 5GHz optoon, will this have any effect on losing signal from the fluorescent lamps??
KR, unhappy Barry
In general, if you’re having signal problems the 2.4GHz option is better. This gives you lower throughput (slower connection) but higher reliability. The reason for this is higher frequency signals are absorbed more over a distance. However, the higher frequency allows for what is effectively a faster connection.
Unfortunately, it would be impossible to tell if your lamps are emitting more interference in the 2.4GHz band or in the 5GHz band without lab equipment that costs about as much as a car.
Hi Tyler again,
Thanks for your helpful feed back, sorry if I duplicated my questions.
I contacted my BB supplier again and they have decided to supply another Hub maybe a more powerful one. Not sure if this will cure my problem or maybe they might consider supplying me a higher grade extender kit. We can only try again and see the results. Thanks again.
Kind regards,
Barry
No problem. You could also try out LED bulbs. Not only will it reduce RFI, it’ll use less electricity!
Hi Tyler,
I also have problems as described by the other Tyler. After complaining, I have been sent a replacement new Hub and extender set but still have drop outs on the extender only at night, however no probIems in the room where the hub is. I thought only last night could it be an influence of our table lamps which are flourescent and used only at night where the extender is based. Then today I read your information and think maybe I was right. Our tv is set for 2.4GHz while my PC based in the room where the hub is set for 5GHz. The tv is connected to the extender using an ethernet cable and my tablet by wifi of course but still fail at night.
I would appreciate you comments.
KR,
Barry
I think I responded to this some in an earlier comment. Your WiFi access point is likely configured for both 2.4 GHz and 5Ghz simultaneous broadcast. Switching to the 2.4 GHz connection will probably help.