Reversed polarity & fluorescent lighting ballasts

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TVH

Member
What are the hazards (if any) of reversed polarity conditions on fluorescent lighting units?
 

TVH

Member
Are you talking about the line voltage input wires of a ballast? There is no danger as it's AC current.
Thank you for the message. I noted, however, that many flourscent light manufactures have reversed polarity safeguards. Why would these safeguards be in place if there was no hazard?

Thank you again for commenting.
 

PetrosA

Senior Member
Thank you for the message. I noted, however, that many flourscent light manufactures have reversed polarity safeguards. Why would these safeguards be in place if there was no hazard?

Thank you again for commenting.

What kind of safeguards have you seen? I've seen fluorescent fixtures that won't start if not grounded, but aside from black and white colored wires, I haven't seen anything that would stop someone from hooking it up with reversed polarity...
 

480sparky

Senior Member
Location
Iowegia
What kind of safeguards have you seen? I've seen fluorescent fixtures that won't start if not grounded, but aside from black and white colored wires, I haven't seen anything that would stop someone from hooking it up with reversed polarity...

Would electronic ballasts be polarity sensitive? Just asking as I have no clue.
 

mivey

Senior Member
My guess who be no as I'm assuming they contain a full-wave rectifier.
I see no reason for them to be sensitive either but it does not mean they are not. Their might be some kind of insulation restriction or they may be trying to use the capacitive coupling for some reason.

I can't remember the thread but there was a question about a furnace being polarity sensitive. I saw no good reason there either.

I emailed & voice-mailed two different furnace manufacturers asking why they cared about the polarity, and why the circuit would not work with reversed polarity, but got no answer (I did get one generic response to contact the local re-seller with any questions, but I wanted an answer from the ones who designed the circuit).
 

ELA

Senior Member
Occupation
Electrical Test Engineer
I see no reason for them to be sensitive either but it does not mean they are not. Their might be some kind of insulation restriction or they may be trying to use the capacitive coupling for some reason.

I can't remember the thread but there was a question about a furnace being polarity sensitive. I saw no good reason there either.

I emailed & voice-mailed two different furnace manufacturers asking why they cared about the polarity, and why the circuit would not work with reversed polarity, but got no answer (I did get one generic response to contact the local re-seller with any questions, but I wanted an answer from the ones who designed the circuit).

Mivey,
In some furnaces it has to do Flame Sensing via Flame Rectification.
I read on this when I had a furnace problem of my own.

Many Flame Sensing controller manuals are very specific about this Sensing method not working if the polarity is reversed.

I believe it has to do with how the rectification is produced and the fact that the resultant DC currents are so small ~ 1 uamp.

Here is one link and you can find many more via a google of Flame Sensing and Rectification.


http://www.achrnews.com/CDA/Archives/4a123d68f9a5a010VgnVCM100000f932a8c0____

Look down a bit for Flame Detection
 

mivey

Senior Member
Mivey,
In some furnaces it has to do Flame Sensing via Flame Rectification.
I read on this when I had a furnace problem of my own.

Many Flame Sensing controller manuals are very specific about this Sensing method not working if the polarity is reversed.

I believe it has to do with how the rectification is produced and the fact that the resultant DC currents are so small ~ 1 uamp.

Here is one link and you can find many more via a google of Flame Sensing and Rectification.


http://www.achrnews.com/CDA/Archives/4a123d68f9a5a010VgnVCM100000f932a8c0____

Look down a bit for Flame Detection
Thanks for the link. I did a quick scan and saw the part about the current going to ground. When I tried to find info before, it just said the sensor was DC so I dismissed it as I did not think of them using the ground. I will read more thoroughly later.
 

mxslick

Senior Member
Location
SE Idaho
Try THIS THREAD for an extended discussion on the reverse polarity topic.

I had some cinema equipment some years ago (see the linked thread) that was very touchy about applied line-Neutral polarity.
 
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