voltage tap on ballast

joncole

Inactive, Email Never Verified
Hello guys and gals.

Went to look at some outside lights today. Had two 20A 240 volt circuits supplying these lights. Took a few lights apart and noticed that the 208 tap was being used instead of the 240 tap. I had 240 volts supply at fixture. None of the lights work.

Could this be the reason they dont work? The balast doesnt smell/look burnt up. I hooked supply to 240v tap but still no light. Is it possible that all of the ballast are bad due to the miswire? Or do you think the light would be ok wired like this? Do you think the light might work for a while like this and then have this problem? Just curious.

Thanks for replies.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I would not think the 208 tap would ruin the fixture or the bulb. If you hook it up at the 240V tap do you measure 240V?
 

joncole

Inactive, Email Never Verified
I had 240v without the load hooked up. I didnt check with load. I will first thing tomorrow. Just seems wierd that its wired this way. I may just have a bunch of bad bulbs. Thanks for reply.
 

broadgage

Senior Member
Location
London, England
I would expect that running a 208* volt ballast on 240* volts would eventualy kill both the ballast and the bulb, especialy in high ambient temperatures or if the nominal 240 volt supply was on the generous side.

I would not expect prompt failure, but eventually, yes.
The equipment would probably seem to work more or less normally, but have an accelerated failure rate.

Was the service once 208 volts ? and then changed to 240 volts without altering the ballast taps
Or were the fixtures secondhand from a facility with 208 volt service.

Many household appliances and most ELECTRONIC ballasts are listed for both 208 volt and 240 volt service, and this sometimes gives rise to the incorrect view that anything intended for 208 volts may be used on 240. (non technical persons sometimes refer to either as "220")

*or in the case of a multi voltage ballast, connecting a 240 volt supply to the 208 volt tap, which is pretty much the same thing.
 

joncole

Inactive, Email Never Verified
Thanks for the reply broadgage.

I think maybe the service did change because all the panels are labeled 208Y/120. This is a large building that is for lease. So I quess at one time an occupant needed 240 3ph delta with high leg and the service might have been changed. Who knows? Looks like I have a lot of ballasts and bulbs to change. Day should go by fast today.

Again thanks for replies.
 

LEO2854

Esteemed Member
Location
Ma
Thanks for the reply broadgage.

I think maybe the service did change because all the panels are labeled 208Y/120. This is a large building that is for lease. So I quess at one time an occupant needed 240 3ph delta with high leg and the service might have been changed. Who knows? Looks like I have a lot of ballasts and bulbs to change. Day should go by fast today.

Again thanks for replies.
Make sure your lamps ANSI rating Matches the ANSI rating on the ballasts.

Welcome to the forum..:)
 

augie47

Moderator
Staff member
Location
Tennessee
How accurate was your voltage reading ?
I think prior to changing anything I would confirm the system voltage with POCO.
If you were reading a true 240 with an accurate meter it is most liklely, as you state, a 240 system. But being an unoccupied building with allowable voltage variables, a 208 system might certainly read well above 208.
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
Hello guys and gals.

Went to look at some outside lights today. Had two 20A 240 volt circuits supplying these lights. Took a few lights apart and noticed that the 208 tap was being used instead of the 240 tap. I had 240 volts supply at fixture. None of the lights work.

Could this be the reason they dont work? ....

Thanks for replies.
Yes it could be. Yes it probably is. Other things may cause said lights not to work but I would bet money you found the problem.
 
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