×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

120/277 volt light fixture
3

120/277 volt light fixture

120/277 volt light fixture

(OP)
can a 120/277 volt compact fluorescent light fixture be installed in a 120/208 volt system?

RE: 120/277 volt light fixture

120V is 120V, or is it not?

RE: 120/277 volt light fixture

Unless this is a trick question...I think davidbeach answered it.

RE: 120/277 volt light fixture

I don't get it. What about the xxx/277 vs xxx/208 part?

Gunnar Englund
www.gke.org

RE: 120/277 volt light fixture

Skogsgurra, The ballast will have two hot leads, one for 120v and one for 277V (use on a 480Y/277V system) plus a neutral, cap off the unused lead.  The 120V can come from a 120V single phase, from one phase of a 120/240V single phase, from one phase of a 208Y/120V, from one of the two 120V phases of a 240/120V delta, or from any other connection that provides 120V (like that 120V delta used on submarines).

RE: 120/277 volt light fixture

That's neat! Never seen that over here. We always install phase-neutral. You learn every day...

Gunnar Englund
www.gke.org

RE: 120/277 volt light fixture

Sadly we have that same 120V delta on trains too.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: 120/277 volt light fixture

Keith, that's interesting.  Would the 120V delta be something in that is still being installed, or does that go back before the Amtrak 480Y/277V HEP system?

RE: 120/277 volt light fixture

Hi David!  Naw, old train stuff not the H.E.P.  I didn't know subs had some of that too.  Most interesting!

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: 120/277 volt light fixture

I've personally installed what they call "smart ballasts", where the ballast knows the incoming voltage, either 120 or 277V, and adjusts accordingly.  Only one hot, one neut., and ground to hook up.  Pretty slick I think,...

Mike

RE: 120/277 volt light fixture

Most new generation electronic ballasts will have the input voltage sensing circuitry which internally selects the volage setting depending on the incoming voltage.  they will self select the correct voltage from 120V to 277V, phase to neutral.  There are still many multi-tap ballasts which will have several "hot" leads, and a neutral, it is just a matter of selecting the lead which matches your system voltage and capping off the rest.

RE: 120/277 volt light fixture

Submarines use 120V ungrounded delta. They do this for battle field relability. In case there is a single phase ground fault during an operation (ie battle)the system can still operate, just as a corner grounded delta.  

Ian Rines
Harris Corporation
Palm Bay,FL

RE: 120/277 volt light fixture

To expand on the "new generation" ballasts:

Most major lighting manufacturers (Lithonia, Columbia, etc.) have made the transition to what are known as mVolt (for multi-volt) Ballasts in the last few years. these ballasts can have pretty much any standad voltage up to 277v applied to them and they will function properly.

RE: 120/277 volt light fixture

Anti-correction SDestimator; From the ballasts point of view they would still think that was a single phase.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: 120/277 volt light fixture

The only distinction between phase & neutral and two phase conductors is that in the phase & neutral case the neutral conductor is near ground potential and in the two phase conductor case neither of the conductors is near ground potential.  Poorly designed electronics could be expecting one conductor to be near ground potential.  Well designed electronics would not have any way of knowing/would not care how the voltage was derived, only the magnitude of the voltage.

RE: 120/277 volt light fixture

Truthfully, I do not know for sure.

I would be hesitant to put an mVolt ballast on a 208v circuit though, as all of the ones I have seen state 120-277 with no mention of 208v.

RE: 120/277 volt light fixture

??? 120-277 V = 120,121,122...207,208,209...276,277 V. Isn't it?

Gunnar Englund
www.gke.org

RE: 120/277 volt light fixture

Possibly. The literature linked above does say they can be used on voltages 108-305, but the thing that makes me leary (without ever having tried it) is the phase/neutral phase/phase difference.

Standard commercial power in the US these days is pretty much all either 480-277 or 208-120 3 phase 4 wire wye connected. This makes both 120v and 277v phase/neutral whereas 208v is phase/phase.

When they say 120-277, they could be indicating they are designed for either of the commonly used Flourescent Lighting voltages, not that they are good for a range of voltages.

RE: 120/277 volt light fixture

That would be contrary to all logic and every standard notation I know of. A ballast is not internally tied to any ground and should be designed to accept being run from phase/neutral or phase/phase.

In the Land of Lawsuits, there should be a large waiver or caveat if that wasn't the case.

Gunnar Englund
www.gke.org

RE: 120/277 volt light fixture

Yes.

I spoke with Osram-Sylvania, and their Uni-volt (mVolt equivalent) will operate with phase/phase 208v applied.

RE: 120/277 volt light fixture

There may be code issues with some ballasts.
For instance, single pin lamps use one of the pins as a switch and the ballast must be wired so that the hot lead goes to the switch pin. (The socket has two contacts which are bridged by the pin on the end of the lamp when it is inserted in the socket.)
The approval may not cover an application with two hot wires.
respectfully

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources