Would universal voltage ballast work on high leg of delta system?

Status
Not open for further replies.

MarkyMarkNC

Senior Member
Location
Raleigh NC
I'm adding a bunch of 2 x 4 fixtures to a warehouse space that has a Delta 240/120V system. The 120V spaces in the panel are all being used, or at least have existing circuits that are run off of them. There are plenty of high leg spaces left, as all of the 2 or 3 pole equipment is coming out of a different panel (also full.)

I got to wondering if, since the ballasts work on both 120V and 277V, would they work on 208V hot to neutral? How do universal voltage ballasts work? How do they "sense" what voltage they have? Would this even be legal? Anyone done this before?

It would sure save a lot of my time trying to track down a couple of unused circuits if I could just wire the lights this way. If this is possible, and/or legal, I'm thinking I would be sure to CLEARLY label every box and fixture with the voltage, for future use. I would hate to be the guy ten years down the road who burns up some piece of equipment trying to tap 120V off my circuit. I know, because I've been that guy before (wow! that fan sure is moving mighty fast!!!)

Thoughts?
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Using the high leg in this fashion has been discussed in the past.

I believe that the consensus was that there is no code that completely prohibits such an installation, however:

1) You would be hard pressed to find suitable OCPD. You would need to find single pole OCPD that was rated for the voltage, and it is likely that the single pole breakers for your panel are only rated for 120V line to ground.

2) The loading on the supply transformers is inefficient. Even with a unity power factor load, the current must flow through multiple transformer coils, so the effect is similar to a poor power factor load connected normally. This might not be an issue if the lights are a small fraction of the load.

3) Non-standard in the extreme, and thus quite confusing to others using the system.

-Jon
 

ohmhead

Senior Member
Location
ORLANDO FLA
Using the high leg in this fashion has been discussed in the past.

I believe that the consensus was that there is no code that completely prohibits such an installation, however:

1) You would be hard pressed to find suitable OCPD. You would need to find single pole OCPD that was rated for the voltage, and it is likely that the single pole breakers for your panel are only rated for 120V line to ground.
Dispatcher-1.jpg


2) The loading on the supply transformers is inefficient. Even with a unity power factor load, the current must flow through multiple transformer coils, so the effect is similar to a poor power factor load connected normally. This might not be an issue if the lights are a small fraction of the load.

3) Non-standard in the extreme, and thus quite confusing to others using the system.

-Jon
Well heres the breaker line to ground 240 volts which is code single pole 15 amp to 100 amp .
 

mivey

Senior Member
Well heres the breaker line to ground 240 volts which is code single pole 15 amp to 100 amp .
We are dis-allowing this information from you until you come across with some info on the breaker. JK, but I would like some details, web link, part number, etc.
 

ohmhead

Senior Member
Location
ORLANDO FLA
We are dis-allowing this information from you until you come across with some info on the breaker. JK, but I would like some details, web link, part number, etc.

Well mivey i just went to the GE s web site picked a 240 volt single phase breaker and thats about it but let me go back and ill get you a part number sorry i didnt post it the last time i got off tracked but ill look it up now .
 

ohmhead

Senior Member
Location
ORLANDO FLA
We are dis-allowing this information from you until you come across with some info on the breaker. JK, but I would like some details, web link, part number, etc.



Well mivey here it is GE FBH16TEO15R its single pole and voltage 240 volts also 277 volt or 347 volts your pick.
 
Last edited:

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
I am certain that you will be able to find single pole breakers rated for 208V line to neutral; simply consider what a 480V or 600V panel requires.

But I think that finding a breaker rated >208V to ground that also fits Mark's panel (presumably rated 240V) is a different kettle of fish.

-Jon
 

ohmhead

Senior Member
Location
ORLANDO FLA
I am certain that you will be able to find single pole breakers rated for 208V line to neutral; simply consider what a 480V or 600V panel requires.

But I think that finding a breaker rated >208V to ground that also fits Mark's panel (presumably rated 240V) is a different kettle of fish.

-Jon

Well 208 volt breaker will not fit in a 240 volt panel and most single phase breakers are slash type 120 /240 v 277/480 v this is legal and its in the code 240 volt single pole rated for line to ground voltage so it could be used on a high leg per the NEC .
 

nez

Member
The universal ballasts usually say 120 thru 277. Any voltage works in that range. I have installed them 208 volt, two legs and they work as intended.
If I am not sure about something I usually call the technical support number and get an immediate answer.
 
Last edited:

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Well 208 volt breaker will not fit in a 240 volt panel and most single phase breakers are slash type 120 /240 v 277/480 v this is legal and its in the code 240 volt single pole rated for line to ground voltage so it could be used on a high leg per the NEC .
Most single pole breakers only have a single voltage rating.
The commonly available (i.e. in someones truck) 2-pole breakers are usually slash rated.
Three pole breakers are almost never slash rated (except for 480Y/277 'lighting panel designs).

Using 1-pole breakers on the 208V wild leg is really no different than using 1-pole breakers on a corner grounded system. If they are rated for it, which they probably are not, go for it.
 

MarkyMarkNC

Senior Member
Location
Raleigh NC
The universal ballasts usually say 120 thru 277. Any voltage works in that range. I have installed them 208 volt, two legs and they work as intended.
If I am not sure about something I usually call the technical support number and get an immediate answer.

Called tech support this morning, and the answer I got was...........probably.

Basically in a wishy-washy roundabout way the tech support guy gave me the impression that it should work fine, but that they may or may not warranty a ballast hooked up to 208V.

I don't want to re-hash the whole 120/240 slash rating thing in this thread. After reading it, the general consensus I got from the other 20 page thread was that there WAS no consensus. My main concerns now are regarding possible future considerations to other electricians.
 
Last edited:

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100210-1448 EST

To answer your original question. A universal ballast using a switching regulator supply should be able to operate at any voltage between the minimum and maximum specified.

These devices will have a bridge rectifier feeding a capacitor input filter to create DC for an electronic switch and inductor that converts the input DC voltage to the desired output DC voltage. From this DC is generated the desired output AC voltage and current limiting. Maybe this intermediate DC stage is eliminated.

I believe the electronic ballasts are operating at about 25 to 30 kHz for lamp excitation to put noise above the audio range and to improve lamp life and efficiency. I believe I read somewhere that there was a claim that about 100 kHz is a more optimum frequency.

Note also that as the input voltage increases the input current decreases.

.
 
Last edited:

ohmhead

Senior Member
Location
ORLANDO FLA
Most single pole breakers only have a single voltage rating.
The commonly available (i.e. in someones truck) 2-pole breakers are usually slash rated.
Three pole breakers are almost never slash rated (except for 480Y/277 'lighting panel designs).

Using 1-pole breakers on the 208V wild leg is really no different than using 1-pole breakers on a corner grounded system. If they are rated for it, which they probably are not, go for it.

Well yes but ECM mag says most SP have slash ratings ? Thats why a single pole 240 volt breaker the one in my post is better than using a 2 pole 120 /240 volt due to the line to ground issue .

Slash rating the lower number is line to ground fault the higher number is line to line fault so a breaker with one rating would be better for a high leg at 208 volts .http://ecmweb.com/mag/electric_understanding_circuit_breaker/ do you agree or is there something i missed ?
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Well yes but ECM mag says most SP have slash ratings ? Thats why a single pole 240 volt breaker the one in my post is better than using a 2 pole 120 /240 volt due to the line to ground issue .

Slash rating the lower number is line to ground fault the higher number is line to line fault so a breaker with one rating would be better for a high leg at 208 volts .http://ecmweb.com/mag/electric_understanding_circuit_breaker/ do you agree or is there something i missed ?
I do not see anything in that article that says 1-pole breakers have a slash rating.

And, the article is wrong in one area. Not all 3-pole breakers have a single rating. I know that the old Square D EH/EHB line of 3-pole breakers were slash rated 277/480V.
 
Last edited:
Status
Not open for further replies.
Top