I recently purchased a new place to me. We have a large horse barn that we pipe FM music to the horses. Last weekend I was in the shop attached to the arena and stalls after dark turned the shop lights on and heard total static on the speakers (they were turned up for the 4th fireworks) all 3 circuits in the shop have 3-4 2 tube 4' T 8 fixtures. I did turn them all off and then each one on. All 3 circuits created the problem. I checked the ground to neutral voltage and it is .129v there is a local ground rod as this is a sub from the house, the ground buss is isolated from the neutral and I tightened everything in hopes it was a bad connection no change. Mid week I added a RFI Filter to the panel. The noise is still there on all 3 circuits, no problems with the 2 HID arena light circuits. Tried a high end Kenwood receiver and amp and still have the noise, not 60hz more like static. Has any one run into this problem and have a fix? There are step up transformers going to the speakers and then step down that kills our neighbors ham radio. But have never run into a problem quite like this. Today I checked both TAC rooms and the isle lights all fluorescent also but no noise on those all fed from the same panel. Update, last night I checked several of the fixtures to verify the ballast they were residential class b not commercial. Maybe tonight I will move the breakers all to L1 then L2 to see if this makes a difference unless any one has a better idea. I did change the circuits to L1 still have the problem. Moved all 3 to L2 noise still there. Tonight I checked the middle and 3rd level lights to double check grounds and voltage from ground to neutral, I did change 2 of the lamps on 1 fixture as the ends were getting a bit dark, still no change all 3 of the circuits still cause the noise, All 6 of the ballast are class B. Only 3 more fixtures to check but will have to wait until tomorrow as I have to put a ladder in our tractor and have the Wife lift me up... I hate doing this and am open to other options. Any Ideas?

  • Have you tried using an isolated 120V to 120V transformer?
    – Kris
    Jul 10, 2016 at 22:05
  • Isolation transformers on 3 separate circuits , I don't think so.
    – Ed Beal
    Jul 11, 2016 at 7:08
  • Tried asking your ham neighbor if they can help? Direction-finding the RFI source might be of use.... Jul 14, 2016 at 0:41
  • He is in the hospital with terminal cancer right now, his son said he has not been transmitting for several months when I first tried to figure this out on the 4th as that was the first time I noticed it. After putting in the transformers on the audio lines we never had the interference, now it is all the time. Climbing the ladder now to double check the grounding on the lower lights tonight but not sure what else to check as I have never had a problem this bad. The TAC room next to the shop is only a few feet away from the reciever. Will update after checking.
    – Ed Beal
    Jul 14, 2016 at 1:18
  • step up transformers going to the speakers? eh, what? The noise only happens when the lights are on? Have you tried a portable radio? Have you verified the speakers work with a hard line signal (from a portable device)? What else has changed, other than blasting it on the 4th? Have you verified that none of your neighbor's HAM equipment is on? What's the model number on the speakers?
    – Mazura
    Jul 15, 2016 at 4:35

3 Answers 3


Thanks for the suggestions, I finally figured it out. This is a new one for me. Several lamps on the top fixtures were loose (still working fine but loose). When I opened the fixtures to check the grounds the noise reduced by the time I got to the last one the noise was gone. My wife thinks when we loaded the hay loft in June we must have shaken them loose. The loft is on the other side of the wall. I have never run into this in the past so it can be something to look for once all the lamps were reseated in the fixtures the "static noise" is totally gone. No other problems found. I did check the ground rod with a clamp and the ground was a solid 2.4 ohms.

  • 2
    That makes a lot of sense. Fluorescents are, after all, arc discharge lights. They know how to strike an arc. So, facing a very small air gap from a loose tube, they would just arc across it, this arc making lots of RFI. Once after I started upgrading 8' fluorescents to electronic ballast, I tried changing a bulb "live" as I had always done. Surprise, the ballast decided it really wanted that lamp lit... the arc leapt a good half inch across the gap. It was like snuffing a DC arc. Didn't do that again lol! Jul 17, 2016 at 21:48

The ground-neutral voltage is no big deal. You ought to have some voltage difference if there's any load on the circuit.

I would start by eliminating radio jamming. Get a battery powered, portable radio - a car or truck will suffice. Do you get the same interference? If so, the problem is radio (RFI). AC power line conditioning will do nothing. Most likely it's duff ballasts, I would be curious about the brand of ballast. Otherwise...

If the panel filter does nothing, that suggests the fox is in with the chickens, i.e. on the same side of the filter. If possible, move the filter so the lights and stereo are on opposite sides of the filter.

To a certain extent, fluorescent ballasts are noisy by nature since they are driving a high frequency signal (2k-50kHz) to the unshielded lampholders and bulbs. But they may also make unnecessary RFI or line noise. GE makes ballasts of superlative quality for about 30% over their top tier competitors. If the lights are the issue, try one and see if that corrects it.

Another option is to go LED, but they too have switching power supplies so beware of quality issues. They are inherently DC and do not radiate high frequency AC anywhere beyond their power supply circuit, which is easily shielded if the manufacturer chooses to.

  • I do this for a living, there are 3 separate circuits, lights only. None of the other motor loads or outlets when using power tools has this problem including; 2 20a HID circuits for the arena, welders.chop saws band saws. Only the 3 separate lighting loads 2 on l1 one on L2.
    – Ed Beal
    Jul 11, 2016 at 6:44
  • 1
    Yeah I wrote this before I realized who the poster was lol Jul 11, 2016 at 18:45
  • What are "duff" ballasts? Jul 15, 2016 at 18:08
  • A slang word for 'not very good' that portrays 'lousy' without implying 'defective'. In this case they can't be accused of the latter as they do make the lamp light... Jul 15, 2016 at 18:44
  • I though duff was the brand of Beer Homer Simpson drank LOL, but I understood thanks.
    – Ed Beal
    Jul 17, 2016 at 0:24

Put a screen over/around the lights... this is called a faraday cage. By putting a farady cage over the lights, you will block the interferance emitted from the ballast (or anything else).

You should read about them... but here's a video: The Difference Between Grounded and Ungrounded Faraday Cages Regarding AM, FM & 2.4 GHz WiFi (microwaves)

In this video, the guy uses chicken wire. Chicken wire is not as good as tighter meshed screens, but it might work okay for your lights.

And here's another video just for fun (informational purposes): Faraday Cage

  • Thanks Ben I have never had to shield class b ballast lights before, I have checked the lower lights maybe tonight I can get the tractor in the shop and get up high enough to check the upper ones. I know the noise was not there several months ago when I installed the system as I had to use step up/down audio transformers to kill my neighbors Ham bleed over. Trying to figure out what has changed.
    – Ed Beal
    Jul 14, 2016 at 18:56
  • @EdBeal I know you know, but I found a succinct little "white paper" from GE. Check this out: gelighting.com/LightingWeb/na/images/… Jul 15, 2016 at 16:15
  • @EdBeal The grounding rod may have been installed after a rainy day, and you might want to double check it... water the grounding rod and see if the reception improves! I would assume the issue must be either grounding or ballast related. Incidentally, arcing and ionization causes a lot of static. If shielding the lights and watering the ground doesn't solve anything, then I would wonder about ionization and arcs. Jul 15, 2016 at 16:30
  • I had not thought about the ground rod being bad, The plant has a ground clamp I will use to check it.
    – Ed Beal
    Jul 15, 2016 at 18:46

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