# ballast output voltage



## brother (Nov 25, 2008)

Had a buddy of mine that was measuring voltage on a common ballast and it was putting out 556 volts! That seemed high even for a ballast. But the light fixture was working fine! I do not recall t-8 type ballast putting out that high of voltage. Does this mean it is going bad?


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## micromind (Aug 11, 2007)

That's actually pretty normal. Some ballasts are even higher. 

A fluorescent tube needs a high voltage to strike the arc inside, then it becomes close to a short circuit. Once the arc is established, the ballast becomes a current limiter. How much current depends on the tube.


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## frenchelectrican (Mar 15, 2007)

brother said:


> Had a buddy of mine that was measuring voltage on a common ballast and it was putting out 556 volts! That seemed high even for a ballast. But the light fixture was working fine! I do not recall t-8 type ballast putting out that high of voltage. Does this mean it is going bad?


I have see that high a voltage level on output leads however if you did check the ballast label sometime they will list the OCV as well so you will find it.

The last 8 footer T-8's they did have 650 OCV so it kinda expected to see that high.

Merci,
Marc


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## brother (Nov 25, 2008)

frenchelectrican said:


> I have see that high a voltage level on output leads however if you did check the ballast label sometime they will list the OCV as well so you will find it.
> 
> The last 8 footer T-8's they did have 650 OCV so it kinda expected to see that high.
> 
> ...


 would you have a link I could see?


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## frenchelectrican (Mar 15, 2007)

brother said:


> would you have a link I could see?


 
This is a link that used with sign ballast.,

http://www.unvlt.com/literature/navigator/pdfs/Sect_7_Sign.pdf

But I am still looking for conventail electroinc ballast info for OCV setting.

I think one of our members in here may have a Advance flourscent bulb trouble shooting. ( I am not sure if he have it now or not.)

Merci,
Marc


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## 480sparky (Sep 20, 2007)

Advance used to have a Fluorescent Troubleshooting Guide, but it disappeared when they got bought out.

However, I managed to save a PDF copy. Click here.


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## socalelect (Nov 14, 2011)

I always wondered what the output was


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## frenchelectrican (Mar 15, 2007)

socalelect said:


> I always wondered what the output was


Socalelect.,

Just be aware that the electronique verison will crank more higher open circuit voltage than old school mangatic ballast can crank it.

And also the electroique ballast will have much higher HZ as well so if you plan to read the OCV the numbers on your DVM may not be right on spot so expect that unless you have true RMS meter.

Merci,
Marc


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## socalelect (Nov 14, 2011)

frenchelectrican said:


> Socalelect.,
> 
> Just be aware that the electronique verison will crank more higher open circuit voltage than old school mangatic ballast can crank it.
> 
> ...


I've got fluke 117 113? 87. And 88 lol I think I'm metered well , I never play with the florecenct lights other than replace lamps and a ballast if its noticeably bad , I actually despize working on lighting 

But was always curious what the voltage output was. I figured it was up there


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## frenchelectrican (Mar 15, 2007)

socalelect said:


> I've got fluke 117 113? 87. And 88 lol I think I'm metered well , I never play with the florecenct lights other than replace lamps and a ballast if its noticeably bad , I actually despize working on lighting
> 
> But was always curious what the voltage output was. I figured it was up there


C'est plenty high to knock ya silly.

I got hit with stupid slimlines couple time before but sign ballasts useally are the worst beside the neons that differnt story.


Merci,
Marc


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## socalelect (Nov 14, 2011)

frenchelectrican said:


> C'est plenty high to knock ya silly.
> 
> I got hit with stupid slimlines couple time before but sign ballasts useally are the worst beside the neons that differnt story.
> 
> ...


Yea I've heard the neon transformers will knock your d!ck in the dirt


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## socalelect (Nov 14, 2011)

I got hit with a capaciter from a disposable camera it hurt like hell


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## Paul J Bonett (Sep 26, 2017)

*residual current*



socalelect said:


> I always wondered what the output was


I take-it that ballasts are to be treated in the same way as transformers and capacitors that retain residual current, in that case, what SAFE method can be used to discharge prior to handling ? Or is it simply the case of turning the power off?


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## macmikeman (Jan 23, 2007)

Paul J Bonett said:


> I take-it that ballasts are to be treated in the same way as transformers and capacitors that retain residual current, in that case, what SAFE method can be used to discharge prior to handling ? Or is it simply the case of turning the power off?


Well now. You got yourself 2 reward points just for putting that out there. Good job. :thumbsup:


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## splatz (May 23, 2015)

480sparky said:


> Advance used to have a Fluorescent Troubleshooting Guide, but it disappeared when they got bought out.
> 
> However, I managed to save a PDF copy. Click here.


That link's no good any more but the attachment ought to last...


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## Southeast Power (Jan 18, 2009)

Paul J Bonett said:


> I take-it that ballasts are to be treated in the same way as transformers and capacitors that retain residual current, in that case, what SAFE method can be used to discharge prior to handling ? Or is it simply the case of turning the power off?


Not the ballasts but the capacitor or two right next to in in HID lighting. They don't usually hold a charge but I always short the terminals out with a screwdriver.
Second, we used to do quite a bit of sign work and had to use 1000 volt labeled THW for the secondary out to the lamp holders.
Neon was a different story and very simple except we used GTO wire on the secondary as the transformers secondary were anywhere from 3,000 to 15,000 volts. Every sign guy has a story about getting hit with that.


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## telsa (May 22, 2015)

brother said:


> Had a buddy of mine that was measuring voltage on a common ballast and it was putting out 556 volts! That seemed high even for a ballast. But the light fixture was working fine! I do not recall t-8 type ballast putting out that high of voltage. Does this mean it is going bad?


You'd be WELL advised to study up on _resonant circuits.
_
Bing the term. Books have been written on these.

ALL of the original fluorescent lamps were designed as resonant circuits.

These BAFFLE the typical electrician -- as they are closer to 'electronics logic' even though they are at power levels.

These are legacy circuits.

Congress as -- essentially -- banned them. They suck down too much power -- and have HEFTY ballasts. 

Indeed, the very term 'ballast' comes from this original tech era.

We STILL use this term of art... but modern fluorescent circuits aren't powered via the same 'logic' at ALL. That's why they can be multi-voltage... and so amazingly power efficient. 

( Magnetic elements are huge power pigs versus what has come to be. )

But, that's another topic for another post.


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## eddy current (Feb 28, 2009)

Here is a funny story of how I learned what the output is on a fluorescent ballast.

I was left alone at a grocery store to repair any burnt lights when I was a first year, had no idea what I was doing. I was told try the bulb first, if it doesn’t work replace the ballast.

I was Working on a fixture that is difficult to get to and don’t want to replace ballast. Using my $10 meter from walmart, I thought I should measure the voltage at the sockets. The meter was only rated for 300 volts, it started smoking and melting!!!!


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## macmikeman (Jan 23, 2007)

eddy current said:


> Here is a funny story of how I learned what the output is on a fluorescent ballast.
> 
> I was left alone at a grocery store to repair any burnt lights when I was a first year, had no idea what I was doing. I was told try the bulb first, if it doesn’t work replace the ballast.
> 
> I was Working on a fixture that is difficult to get to and don’t want to replace ballast. Using my $10 meter from walmart, I thought I should measure the voltage at the sockets. The meter was only rated for 300 volts, it started smoking and melting!!!!



That is a funny story. Telsa's story was funnier though.


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## Paul J Bonett (Sep 26, 2017)

Thanks Guys !


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## GeneC (Aug 28, 2017)

Everything everyone said is true, No need to test a fluorescent ballast for output or proper voltages, It's either good or bad or tombstones may be bad, Just change it. If you are converting watch your head old magnetics are heavy. I buy the workhorses by the case, can be used for multiple applications, even CFL. Mostly deal with HID, 480 volt, I don't care about the output voltage on ballast, If changing bulb don't work then pole gets disconnected. Most times capacitor is shot, Other times ballast, One thing to remember the outputs on all these lights is high so I don't care what the output voltage is, It's working or it's not. You get hit by a capacitor you won't care either. Stick you finger in a spark plug socket you'll know. Oh and by the way being ungrounded don't help. Moist air will get you trust me I know. Be safe


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