277v on 120v sconce ??

[mltech]

Found 10 sconces in a commercial structure that were installed on a 277v multiwire branch circuit. These are decorative 120v medium base socket type fixtures with 120v screw in led bulbs. Not even sure how they are working?
I expressed my concerns and the potential liability of the installation but got some push back, "the board will have to approve a fixture change and that could take awhile." My feeling is that I am now some how responsible since I found the problem. I plan on writing a letter and would like to provide some proper code violations to support the findings. Any help is appreciated.

 

[jap]

Are you sure they are 120v lamps and not 277v lamps?

They make 277v rated A19 LED screw in bulbs.

The question would be is the fixture actually rated for 277v.

JAP>

 

[Tulsa Electrician]

Auto transformer?
May not be an issue or code violation.

Now if you measure 277 at socket and fixture listed for 120 volts you then would have a violation .

 

[mltech]

Definitely 277v at the socket, actually 279 volts. Trying to find the specs on the fixture. No label on the one we took down?
The installed bulbs are all 120v rated?

 

[jap]

Are they dimmed way down.... LOL!!

JAP>

 

[charlie b]

A component's voltage rating is based on the ability of its insulating materials to prevent leakage current from the current-carrying metals to the exterior non-current-carrying metals. Exceeding a component's voltage rating risks short-circuit currents, arcs, sparks, and fires. If you are certain the bulbs are rated at 120 volts (your last post showed that as a question), then I would recommend sending a letter informing the owner of your concerns. I would go one step further to get something in return that you could bring to a courtroom to prove that you informed the owner of your concerns ("just in case").

You don't own this problem. Finding the problem doesn't convey ownership to you. However, failure to notify the right persons of the problem might put you at risk of getting blamed for anything bad that happens.

 

[mltech]

Thank you Charlie.
The question mark was inadvertent but relative as to how the 120v bulbs were still working.

 

[tom baker]

Is this a standard-medium base socket? I need to check but pretty sure it has to be a mogul base for 277. Likely the incorrect luminaire which violates its listing

 

[petersonra]

It appears you informed them of a potential problem. That is all you should do unless someone gives you a p.o. to do more.

 

[J2H]

Thank you Charlie.
The question mark was inadvertent but relative as to how the 120v bulbs were still working.

I would guess that while not designed for it and a listing violation, that the LED bulbs contain a built-in switching supply that "auto-regulates" to the line voltage.

 

[hillbilly1]

I’ve seen Metal halide lamps that looked exactly like an A19 incandescent, but the socket voltage should have been higher than 279, unless maybe it was an electronic ballast. I did come behind someone that stuck an incandescent lamp in one, and it just had a dim yellow glow. Apparently the ballast limited the current enough.

 

[Dsg319]

I’ve seen Metal halide lamps that looked exactly like an A19 incandescent, but the socket voltage should have been higher than 279, unless maybe it was an electronic ballast. I did come behind someone that stuck an incandescent lamp in one, and it just had a dim yellow glow. Apparently the ballast limited the current enough.

Maybe he is using a low impedance meter? If so he should have seen a nice blue arc when disconnecting from testing lol.

 

[Eddie702]

Once you figure out what you have I would send a letter return receipt requested or something similar. CYA

 

[mtnelect]

That's how I got "Zapped" with 480 volts, while changing out a 277-volt light switch. My arm was numb for a day. After that incident, never worked anything live again. Isn't against the code to have more than one leg of 480 volts in a switch box ?

I am talking about safety. Large office buildings are always 277 voltage lighting. There should be a NEC requirement for lighting only not to have 480 volts present in a switch box.

 

[roger]

There are medium base 277 V incandescent lamps, I have used a few.

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[n1ist]

You can get 277v bulbs with A19 bases. I used them a lot at a previous job as test loads. You do need to watch the sockets as many are only rated at 250v, but there are 600v ones out there

 

[jap]

That's how I got "Zapped" with 480 volts, while changing out a 277-volt light switch. My arm was numb for a day. After that incident, never worked anything live again. Isn't against the code to have more than one leg of 480 volts in a switch box ?

I am talking about safety. Large office buildings are always 277 voltage lighting. There should be a NEC requirement for lighting only not to have 480 volts present in a switch box.

There may be multiple 277v circuits in a switchbox just like with any other voltage.

Any time you get shocked you've got the potential to receive all of the power the utility transformer has to offer regardless of voltage.

JAP>