Ungrounded fluorescent lighting.

[Zeke]

I had a thread or was on a thread some time ago about this subject. Lately I have been reading up on electrical wiring and some theory (thanks to the extreme generosity of a GJ member). I guess I shouldn't call it theory because it's fact.

Anywho, I read about the electrical field generated by many electrical devices and transmission. Seems that there is indeed a need to drain off residual current accumulating in and around electrical equipment to earth.

So, there's the crux of the question; does having fluorescent lighting fixtures on an ungrounded circuit (as in an old house) cause modern day electronic ballasts to die prematurely?

I think it does.

 

[wyliesdiesels]

The 10 yrs or so I've been in the electrical field, I've never heard of such a thing. The way to check for such a think would be to put a clamp meter on the egc coming from the fixture and see if there's current. The only thing is, a ballast is only 2 wire input, so it would have to give off that electricity via inductance through its metal chassis!

But I'm gonna have to say no, not possible. A transformer doesn't store electricity and I don't believe there's caps in ballasts, so there wouldn't be any residual current to bleed!

 

[awdblazer]

the ground is only there for your safety

 

[May Pop]

Many of the newer ballasts are of lower quality so that may be the problem.

 

[ForceFed70]

There is no need to "drain off residual current" in fact, there is no residual current at all.

The only purpose of the ground is for electrical safety.

 

[Zeke]

I hear you all. But... an FL has a much bigger chassis than most other fixtures. Sure, a ballast has only 2 wires. So do a lot of double insulated motors. Are you saying you'd run your CAT 5 next to a ungrounded motor?

I realize this is an academic question. Perhaps if you can cite why or why not, that would help. I'm happy to believe that my lamps are dying prematurely for other reasons.

Oh, did I say ballasts before? Sorry, it was the lamps. The circular kind if that makes any difference. Oh, and the one that is ventilated better than the other is the one that died.

 

[Alchymist]

I hear you all. But... an FL has a much bigger chassis than most other fixtures. Sure, a ballast has only 2 wires. So do a lot of double insulated motors. Are you saying you'd run your CAT 5 next to a ungrounded motor?

I realize this is an academic question. Perhaps if you can cite why or why not, that would help. I'm happy to believe that my lamps are dying prematurely for other reasons.

Oh, did I say ballasts before? Sorry, it was the lamps. The circular kind if that makes any difference. Oh, and the one that is ventilated better than the other is the one that died.

I wouldn't run a CAT5 or any other signal wire next to a motor, grounded or ungrounded. It's the magnetic field you have to worry about.

 

[Falcon67]

I wouldn't run a CAT5 or any other signal wire next to a motor, grounded or ungrounded. It's the magnetic field you have to worry about.

And the twists in the pairs should negate any field effect. We have lots of CAT5 in old buildings here, running next to or over 277V flo lights, down chases shared by 3 phase power and in closets with big motors on air handlers for 2 and 3 story buildings. No problems. In retrofit installations, youo don't often get to choose where the equipment goes. I have two switches and a big patch panel in the vestibule of a women's rest room. You get what you get. The building I work in was built in 1947 as a library. It's not now. You should see the panel mess in the basement.

 

[Vinci]

And the twists in the pairs should negate any field effect. We have lots of CAT5 in old buildings here, running next to or over 277V flo lights, down chases shared by 3 phase power and in closets with big motors on air handlers for 2 and 3 story buildings. No problems. In retrofit installations, youo don't often get to choose where the equipment goes. I have two switches and a big patch panel in the vestibule of a women's rest room. You get what you get. The building I work in was built in 1947 as a library. It's not now. You should see the panel mess in the basement.

The twists in UTP wire will reduce crosstalk and EMI, but not negate it. They exist primarily to help reduce interference from the other pairs in the same cable, not the environment outside it.

The effects are more noticeable at higher speeds, but that doesn't mean that slow connections won't "work" well enough to go unnoticed in some environments. This is a lucky thing for me, since some of the buildings at work are old and wired very poorly, so they would not be up to the task if we needed to really push traffic on those wires.

You wouldn't want to run data lines next to any fluorescent fixtures or electric motors.

 

[nehog]

the ground is only there for your safety

True!

There is no need to "drain off residual current" in fact, there is no residual current at all.

The only purpose of the ground is for electrical safety.

True!

But...

I've seen some fluorescent lights that would not light without the ground connected. I always put that down to marginal bulbs or ballasts.

 

[ForceFed70]

I hear you all. But... an FL has a much bigger chassis than most other fixtures. Sure, a ballast has only 2 wires. So do a lot of double insulated motors. Are you saying you'd run your CAT 5 next to a ungrounded motor?

I realize this is an academic question. Perhaps if you can cite why or why not, that would help. I'm happy to believe that my lamps are dying prematurely for other reasons.

Oh, did I say ballasts before? Sorry, it was the lamps. The circular kind if that makes any difference. Oh, and the one that is ventilated better than the other is the one that died.

Zeke you've got some strange ideas!

Grounding the fixture does nothing to prevent EMI. Running a CAT5 cable near a FL fixture or a motor is a bad idea no matter how they are wired.

Are you getting grounding mixed with with a faraday cage effect or something?

And the twists in the pairs should negate any field effect. We have lots of CAT5 in old buildings here, running next to or over 277V flo lights, down chases shared by 3 phase power and in closets with big motors on air handlers for 2 and 3 story buildings. No problems. In retrofit installations, youo don't often get to choose where the equipment goes. I have two switches and a big patch panel in the vestibule of a women's rest room. You get what you get. The building I work in was built in 1947 as a library. It's not now. You should see the panel mess in the basement.

As Vinci has mentiond, the twists are more to reduce crosstalk than to protect against EMI. And they are far from prefect at blocking EMI which is why you often see twisted pair surrounded by a foil shield. The foil shield does far more to protect against EMI than the twists.

I know you've got ****** wiring that still works in some of your old buildings but that doesn't mean it's right. What your CAT5 used for? High speed networking and a fire/security alarm system are vastly different things.

There is a reason this sort of thing is against code and best practices.

True!



True!

But...

I've seen some fluorescent lights that would not light without the ground connected. I always put that down to marginal bulbs or ballasts.

If that's the case, you'd never be able to GFCI protect that circuit. And I would 100% agree that there is a problem with the balast and/or the wiring.

 

[Zeke]

I found this with regarding the starting of the lamps:
" A grounded reflector close to the lamp, and a grounded line circuit are required to provide a capacitive starting aid for the lamp."
Source: http://www.unvlt.com/techsupport/trouble_shooting/elct-qa.html

More:
" Most electronic ballasts arrive with the disclaimer "do not use in conjunction with a ground fault interrupting ("GFI") system." This is simply acknowledgement of the fact that electronic ballasts, like many diode-rectified loads, dis-charge a tiny amount of current in the ground wire. If there are enough ballasts on the system and a GFI is in effect, it will sense the current flow and shut down the circuits. GFI's are normally only found on those systems where current carried by the ground conductors poses a safety problem...as around swimming pools, showers, etc."
Source:http://www.tvss.net/pq/ballast.htm

Here's a random quote from an electrician I know:
"You absolutely need to ground the ballast. That is an electronic ballast and MUST be grounded to prevent the high frequencies from creating problems."

There's more, but I'll leave it at that for the time being.

I have strange thoughts? Maybe, maybe not.

 

[ForceFed70]

Well now we're getting on to different topics. I was only talking EMI. Never did I say that you shouldn't ground the fixtures.

There are a ton of things that can cause nuisance GFI tripping. Multiple FL fixtures would certainly be one of them.

A ballast that requires a capacitive starting aide like that is not something that I would be investing in.

As far as your electrician friend: I'd like to see some quantifyable data instead of a quote from some random electrician. Electricians receive very little training/instruction when it comes to EMI. You'd be much better off talking to someone who deals in the RF field (radio tech, antanae design, etc) or an electrical engineer when it comes to this sort of thing.

For the record: Any piece of metal can act as an EMI shield and I certainly believe that grounding that piece of metal will also effect it's performance as a shield. But no matter how you slice it, the fixture (grounded or not) is going to do very little to block the EMI being emitted from that ballast. 90% plus will still escape. This is the equivilent of you telling me that your metal garage door will block out all of the local radio stations if you attach a ground wire.

 

[Zeke]

I don't understand a thing about what I'm asking. I realize I have gone from ballasts to bulbs and HF to RF to EMI. Or you have. I know now that my motor comparison was ridiculous.

Instead of poo-pooing this, let's understand it. I'm sorry about the random electrician's quote. Indeed, it was I that asked for sources and citations. So far, I'm the only one to have to provided any sources for the opinions given other than the "electrician" (whom, BTW, I could have cited, but I didn't).

 

[Alchymist]

I don't understand a thing about what I'm asking. I realize I have gone from ballasts to bulbs and HF to RF to EMI. Or you have. I know now that my motor comparison was ridiculous.

Instead of poo-pooing this, let's understand it. I'm sorry about the random electrician's quote. Indeed, it was I that asked for sources and citations. So far, I'm the only one to have to provided any sources for the opinions given other than the "electrician" (whom, BTW, I could have cited, but I didn't).

Having worked something like 40 years in electrical/electronics areas, everything from DC to 22 GHz, and on subjects from EMI to ESD, RADAR to ECM, TDR to PDM, I stand by my statement. Source enough?

 

[theoldwizard1]

...I read about the electrical field generated by many electrical ... transmission (lines)...QUOTE]
If you stand near a very high voltage transmission line it will light up a florescent bulb !

MythBuster episode

 

[Zeke]

Having worked something like 40 years in electrical/electronics areas, everything from DC to 22 GHz, and on subjects from EMI to ESD, RADAR to ECM, TDR to PDM, I stand by my statement. Source enough?

Of course. However, you addressed my ignorant comparison of a 2-wire electric motor to a 2-wire ballast by saying that no signal wire should be run near a magnetic field.

Now, how about this stuff about HF and electronic ballasts and the lighting tubes themselves. I have such a hard time explaining this that I am not sure what did fail a year or so in my fixtures. Seemed to me I changed out the lamps after they quit working and found it was the tiny ballast that was defective. So, IIRC (finally!), the ballast killed the circular tubes as it was dying itself. These are my kitchen fixtures and they get switched on and off many times a day.

It was when I was searching for parts that I stumbled onto the grounding issue. I live in a house built in the 30's. All of my lighting fed through the attic is ungrounded knob and tube wiring. Most of the rest of the house has been rewired from the crawl space with new grounded circuits as has been the garage and laundry.

My fixtures use a 8 and 12" version of these:

The ballast is in the center of both of these.

 

[Alchymist]

Of course. However, you addressed my ignorant comparison of a 2-wire electric motor to a 2-wire ballast by saying that no signal wire should be run near a magnetic field.

Now, how about this stuff about HF and electronic ballasts and the lighting tubes themselves. I have such a hard time explaining this that I am not sure what did fail a year or so in my fixtures. Seemed to me I changed out the lamps after they quit working and found it was the tiny ballast that was defective. So, IIRC (finally!), the ballast killed the circular tubes as it was dying itself. These are my kitchen fixtures and they get switched on and off many times a day.

It was when I was searching for parts that I stumbled onto the grounding issue. I live in a house built in the 30's. All of my lighting fed through the attic is ungrounded knob and tube wiring. Most of the rest of the house has been rewired from the crawl space with new grounded circuits as has been the garage and laundry.

My fixtures use a 8 and 12" version of these:

The ballast is in the center of both of these.

Zeke,
One of the worst things you can do to an electrical or electronic device is to turn it on and off. Switch contacts wear and arc, surges at turn on and turn off are hard on components, etc. Power failures are the worst on/off sequences ever. Voltages go all over the place, including well over design limits. Best thing to do in a power failure is turn off everything and wait until the power is back on and stabilized before turning things back on.

Another point to consider is that things like fluorescent lights are designed to a price point. Quite often one component ( ie, ballast) will fail and take another component with it. Can a ballast be designed to fail safe? Of course, but it costs more....

As to signal wires - NEC specifies that they be run separate from mains for several reasons, among them safety and crosstalk.

When designing an electronic device, many factors come into play - radiated RF, conducted RF, ground current leakage, electrostatics, electromagnetics, just to name a few. If human eyes could perceive energy in the RF spectrum, the whole world would be aglow like a rainbow.

 

[Zeke]

Yes, I know the world would look like that if we could see it. The aurora borealis tells us a bit about that world. I've been reading about another world as well; that of grounding. While we on the West Coast should be as concerned as anyone, there aren't too many examples of a grounding circle ranging scores of feet and with 8-10 rods around here.

Those in FL like their grounds, not to mention any place where lightening is sometimes a daily occurrence. So, in the Rex Cauldwell book I was referred to, a man is sitting in his chair when lightening shoots OUT of the outlet and travels to a "grounded flue" in the room. The author did not mention what type of flue, perhaps an exposed stove flue. Ol' Rex likes to bond everything including metal duct work.

I'm going back to my light fixtures with their own bit of wild current. Seems to this lay electrical student that the neutral is carrying back the equivalent of the current used to power the ballast. Meanwhile, other things are going on. I still want to think that a ground will provide more than the safety of an equipment ground.

Is this a similar situation as to why a large antenna needs a very good ground? Again, I said "similar." Not going to fall in that trap again comparing apples to oranges. I'm not referring to the need to ground an antenna because of lightening. I'm referring to receiving the signal and the ground plane.

Yes, I've been known to beat a dead horse. Sorry.

 

[Alchymist]

The bit about lightening shooting out of the outlet reminds me of a time many years ago when during a lightening storm a ball of fire flew from the telephone to the kitchen sink in my parents home, a distance of about 6 feet.
If I hadn't been looking in that direction I would have never seen it, but I surely heard it.

As to grounds, one must distinguish between earth ground and the EGC - equipment grounding conductor. They are normally tied together in the main panel, (neutral, ECG, earth ground), at any detached sub-panel, ( EGC and earth ground, separate from neutral) and at the utility pole the transformer neutral is connected to an earth ground. Commercial and industrial systems are even more elaborate.

 

[wyliesdiesels]

.....Is this a similar situation as to why a large antenna needs a very good ground? Again, I said "similar." Not going to fall in that trap again comparing apples to oranges. I'm not referring to the need to ground an antenna because of lightening. I'm referring to receiving the signal and the ground plane.

Yes, I've been known to beat a dead horse. Sorry.

I dunno for sure but I do know that with AM radio, if the antennas are grounded in ocean water, they put out signal that's receivable for hundreds of miles. An electrician who use to be an am radio disc jockey told me about that. There's an am radio station in santa cruz that has antennas grounded in ocean water(they sit in a lagoon connected to the bay!).

As far as the other subjects discussed in this thread(the comments came in too fast for me to respond), I would never put low voltage cable next to high voltage wiring(I do both). Have had customers with buzzing phone lines in the past(I didn't do the original phone wiring, but I had to fix the problem!) And I second the comment about the twists in UTP not negating noise. I had to rerun some CAT6 in a hotel that was picking up interference from FLs and motors. We ultimately ended up going with shielded CAT6 to solve the problem!

 

[Zeke]

Well, the new ballast lasted almost 3 months. The other fixture is still original, 4 years old and gets switched on with this one every time. Something is eating up my ballasts.

But first, I will double check my wire nuts. I'm usually very careful when nutting up wires.

 

[wyliesdiesels]

Well, the new ballast lasted almost 3 months. The other fixture is still original, 4 years old and gets switched on with this one every time. Something is eating up my ballasts.

But first, I will double check my wire nuts. I'm usually very careful when nutting up wires.

Strange! All i can add is that i know it says to make sure ballasts are grounded within x-feet of the reflector. But im not a lighting engineer so im not sure how that applies to issue with ballast dying prematurely! Maybe theres an engineer on here that could help u out! Definitely weird though!