Home>Discussions>ELECTRICAL & LIGHTING>Fluorescent fixture creates TV static -- WHY?
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Little Cabbage
Fluorescent fixture creates TV static -- WHY?

We've had an expensive and very reliable fluorescent fixture in our small galley kitchen for ten years. It's a long, 42 inches or so, four-tube fixture. :) Then the ballast 'went bad', the lights wouldn't come on.

So, off to the long-established, professional lighting store we have worked with for years to order a new ballast. Had it properly installed by a licensed contractor we've worked with for years.

Guess what, the light is great but whenever the fixture is on, it creates static on the VHF stations on all the TVs in the house! (We are lucky, we have excellent reception with a roof aerial, no need for cable).

The contractor is scratching his head; the store vaguely thinks we need to 'check the grounding wire' (but that makes no sense, it wasn't changed); two other knowledgeable how-to types both said they thought the new ballast was 'bad'. However, neither of them thought there was any way to test the ballast (!)

The bulbs work fine in another fixture (different circuit), so it's not the bulbs.

We would really appreciate advice from any knowledgeable electricians out there -- THANK YOU!!

djohns
Re: Fluorescent fixture creates TV static -- WHY?

I think what they mean is , check the ground wire to see if it was properly reconnected . Was the ballast a direct replacement for the old one or a universal type of replacement ?

Little Cabbage
Re: Fluorescent fixture creates TV static -- WHY?

It was specifically for this fixture; had to be ordered.

Could the ground wire really do this? Can you please explain, I really don't understand electrical at all (but I'm great with a paintbrush).

It's strange because when it was taken down (I was there, very interested), three of us noted that there did not seem to be any ground wire at all coming from the ceiling...which seemed odd since the fixture had been working great for over 10 years. This is an older (1940s) home; the fixture replaced the previous fixture which has 'always' been there, in the middle of the kitchen ceiling.

Questions:

1. Do you think we should pursue the ground wire theory? Even if we have to somehow rig up a new ground wire through the very difficult-to-reach attic?

2. Can't they test the 'new' ballast to see if something's wrong with it?

Thanks for any advice!

djohns
Re: Fluorescent fixture creates TV static -- WHY?

I have seen flourescents act weird when not properly grounded . Not often . But I have seen it . There should have been a ground wire coming from the ceiling box but it's very possible that it may not exist at all . If the old ballast functioned fine without it , and the new one is an exact replacement , well ....

Not sure how you would test a ballast , but I know where to go ask . I shall return .:rolleyes:

canuk
Re: Fluorescent fixture creates TV static -- WHY?

I'm leaning toward a faulty ballast or it's not quite an exact replacement.

The ballast has basically a coil inside that regulates the electrical current for the actual fluorescent lamps... the recent modern types will also have electronic components to help control the electrical current. Usually an indicator the ballast is failing is an audible hum which is from this coil inside having loose iron plates that vibrate. This can cause what is known as parasitic currents that can lead to electro-magnetic interference (EMI) which a ground conductor wouldn't help.

Just a thought.

kentvw
Re: Fluorescent fixture creates TV static -- WHY?

Just a couple of thoughts.

I too would wonder if the ballast is an exact replacement. It is pretty common for us to replace old magnetic ballasts with electronic ballasts and switch from T-12 lamps to T-8's. Electronic ballasts can create more interference than magnetic ones. RIF (Radio interference filters) can be purchased and installed in the fixture.

The FCC actually has regulations regarding ballasts and I have seen/herd blurbs here and there that noncompliant ballasts are being sold. The ballast should have something written on it that says it complies with such and such FCC regulation.

You say you are on an antenna and not cable. I would then wonder if you are using a shielded cable with a well grounded shield from the antenna to the TV's.

Some ballasts do say to ground the ballast and install the lamps no more than a fixed distance from a grounded reflector but in all honesty I have no idea why.

Little Cabbage
Re: Fluorescent fixture creates TV static -- WHY?

Re: the TV antenna cables....I have no idea if they are 'shielded'. It was all professionally installed about 12 years ago, and we've had no problem until this new ballast situation.

We're not hearing a 'hum' from the ballast, but I'm going to take it apart, check the numbers on the fixture (again) and head back to the lighting store's experts.

If anyone else has special insights on this problem, it would be very appreciated if you would share them here. I will keep checking.

Thanks, y'all!

JacktheShack
Re: Fluorescent fixture creates TV static -- WHY?

I certainly don't know as much about this topic as the above posters, but I'll give it a shot.

It seems to me the contractor that put in the new ballast has a duty to make good on the installation until the problem is corrected, usually charging extra if additional components are installed, but not charging for any additional labor.

Light a fire under that guy & tell him to get cracking.

The electrical supply line should be a 3-wire hot (black) white (neutral) bare (ground) with the ground connected to the steel housing of the fixture; the ballast should be completely enclosed in metal & firmly grounded to the fixture steel housing.

This should be checked by the contractor on a call-back.

Ballasts are low-cost & easily installed; quite often this type of problem is quickly cured by simply trying another ballast by substitution; there are thousands of them available, many different types; they can be so individualistic as to the way each one behaves in a circuit.

Take a stroll thru the electrical dept. of Home Depot or Lowe's if you want to see how many ballasts they have on their shelves.

Sometimes an older, non-electronic ballast is tried (often in stock at a supply house that has been around for years); these often work where an electronic one will not.

Another test would be to put a 3-prong plug on one side of a long piece of romex, connect the other end to the fixture & try different plugging into different circuits throughout the house to see if a different circuit will clear up the problem.

Another alternative is to run a separate line from the fixture back to the main panel & try connections to each circuit until the RFI disappears.

There are line filter strip receptacles that are sold at retail stores that will filter out electrical line noise, but this would only fix things for one TV, if it works at all & they cost $10-$20 each.

What's the interference doing on the TV screen??

Line noise transmitted thru the wires will seem to stand still or move slowly upward, often as black, thin horizontal line segments, since the TV picture is 60 cycles as is the house current.

RFI if by chance transmitted by the flourescent bulbs themselves will have more of a bending effect on the TV pix; sometimes there is a wide black vertical bar that slowly moves right to left or left to right across the pix (horizontal blanking bar).

Kent referred to the shield cable that brings the radio frequency TV signal down from the roof antenna.

This is usually done by a round 75 ohm coaxial cable; this is usually finely printed along the cable.

In rare cases the shielded cable can be older "ribbon" cable that has an aluminum shielding just under the plastic coating.

Canuk mentions EMI and parasitic currents that are caused by some defective ballasts; all the more reason to try another ballast IMHO.

There's an outside possibility that either the ballast or the flourescent tubes are transmitting the interference thru the air, but it is much more likely being fed into the electrical wires.

Kent makes a good suggestion in installing line filters inside the fixture housing on the hot & neutral wires going into the ballast; these are widely available & are mentioned in the sites below; it's something that can be easily done by the contractor that installed the new ballast.

There are tons of sites on the internet that deal with RFI problems on TVs caused by flourescent fixtures & ballasts.

Google "flourescent fixture ballast rfi" (without the quotation marks).

http://lists.contesting.com/_rfi/2005-09/msg00058.html
http://www.simkar.com/troubleshooting.htm

JLMCDANIEL
Re: Fluorescent fixture creates TV static -- WHY?

You said there was only 2 wires in the ceiling. You may have romex cable which has a metal jacket that is attached to the box, and the jacket is used for ground. During the removal and reinstall a good connection may not have been established. This can be checked by attaching a volt meter with one lead on the hot wire and the other on the box, if you read 120volts the box is grounded.
A ballast gives off EMI and RFI, the metal case of the fixture acts as a shield if grounded and carries these signals off to ground. A quick test would be to ground one end of a wire and touch it to a bear spot or ground screw in the fixture to see if the interference disappears. If it does have the contractor check to see if the wiring is romex and it is making good contact with the box, check the mounting screws for the ballast, make sure there is a star washer installed or the paint is scraped off the tabs of the ballast. Paint will act as an insulator.
Jack

Little Cabbage
Re: Fluorescent fixture creates TV static -- WHY?

The licensed contractor (actually three of them have worked and scratched their heads on this) are all my relatives....and good guys! :)

Thanks to all for your ideas, which will be pursued in earnest this weekend. Will let you know what develops.

The static on the TVs is lines and sound, it fouls up the picture, but only on channels 2, 3,4,5,6,7. Others don't seem affected.

Thanks again! And if anyone else has a good thought, please post it, I'll be checking regularly.

PS: TOH is the best program on the tube! I've been a fan for many, many years! Delighted to see the 'Ask TOH' section added. It's fun to see the expensive renovations and the latest building stuff, but more helpful to see the guys working on 'everyday' problems we can all relate to more easily.

miscreant
Re: Fluorescent fixture creates TV static -- WHY?

there are devices out that test faulty electronic ballast - GTI makes one I know for sure... test pens and AVO meters. ask an electrician about the latter. good luck! -Fishfool @ The Reef Tank

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