I 'am working on a public library and the plans call for mounting 277 volt open lamp type flourescent strip fixtures under the top shelf of the book cases. The shelfs are made of steel and also all of the supports. They are fed from floor boxes. Is this a legal installation per NEC.
277 volt bookshelf lighting
- Thread starter wferg
- Start date
- Status
- Location
- Massachusetts
I do not know of any NEC rule prohibiting it but if it was me I would have used 120 lighting.
When 277 volt light circuits fail they seem to blow holes in the side of fixtures, spray sparks etc. I don't see the same thing happening with 120 volt lighting circuits.
When 277 volt light circuits fail they seem to blow holes in the side of fixtures, spray sparks etc. I don't see the same thing happening with 120 volt lighting circuits.
ultramegabob
Senior Member
- Location
- Indiana
I have seen that with older magnetic ballasts, but havent really noticed it happening with the newer electronic ones so much.
- Location
- Massachusetts
You lost me, what does the ballast have to do with the branch circuit fault energy?:-?
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
The engineer who designed our new library must think along the same lines. All regular ceiling troffer lighting is 277v., but cabinet, shelving, and wall sconces are 120v, because they are more prone to damage by patrons or employees.
- Location
- Massachusetts
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I see nothing wrong with it. If I remember correctly the open voltage on a ballast is about 600 volts whether the supply is 120 or 277 volts. I would be more concerned with that than the input voltage.
- Location
- Massachusetts
It is legal but IMO a poor design.
Of all the large retail I have done all the 'high lighting' will be 277 and all the low lighting in shelving, displays etc will be 120.
It's not the voltage the worries me as much as the fault energy of the branch circuit.
Just Sunday I was at a Kohl's store fixing a reloc on the back of a 277 volt 2 x 4 trougher that failed turning about 25% of the back of the fixture black as coal, I fixed another one a few months ago that when the reloc failed it burnt a hole right through the fixtures KO plate without any actual contact.
I have some pictures of that one, I will try to find them.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
I hate showing my ignorance, but what is a reloc please?
- Location
- Massachusetts
Re-Loc is just one particular brand of plug together building wiring.
Truth be told the one at Kohl's was actually another brand than re-loc but is very similar.
Check this site.
http://www.relocwiring.com/Applications/RecessedCeiling.aspx
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Thanks Bob.
- Location
- Massachusetts
No problem at all, you can see it in the ceilings of most Lowe's or Home Depot's. That is why you will often see what looks like loops of spare MC cable at each fixture. The whips come in pre-made lengths so you have to coil up the slack.
ultramegabob
Senior Member
- Location
- Indiana
I was picturing a fluorescent ballast failing, not the wire itself arcing out to the fixture, I have seen large holes blown in magnetic ballast housings, electronic ballast dont seem to do that as much. I see now you were talking about the wiring itself so nevermind
- Status