A friend asked about hooking up 220 volt light fixtures in a commercial building. How can he run them using a 3 way switch and what is the best method for hook up? Do you break both lines going to the light? He is familiar with 110 and 220 in residential and such but never a 3 way 220 line. Thanks
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Since a "normal" 3-way is an SPDT switch (single pole, double throw), for 220V you'd need a DPDT.
Forrest
Commercial building--call a pro. Anyone not familiar with higher voltage lighting should not be working on it, for their safety and the safety of the building occupants.
In commercial systems, things can get real ugly, real fast when you don't understand the big picture. I got called in once to deal with the aftermath of a handyman who tried to replace a fluorescent fixture. He didn't have a clue about three-phase power used in commercial buildings, so he shut off power to the one circuit he was working on, and proceeded to replace the fixture. That fixture happened to have the neutral splice for the three separate phases. When he broke the neutral splice, which served all three 120v circuits, the resulting overvoltage blew out several computers on the other two circuits. He was a real popular guy around there...
Anyway, is it actually 220 (or rather 240)?
In my experience, the voltage is 277 in commercial occupancies (office buildings, storefronts in malls, etc) that have lighting powered at voltages above 120V. That's 277v-to-ground, and it bites REAL hard.
At any rate, 3-way switching is set up is the same whether in a 120v circuit or a 277v-to-ground circuit. If it's a 240v phase-to-phase circuit, which I've not seen for lighting, the arrangement is different.
Wiring arrangement aside, a big difference with 277v lighting is in the switches, they have to be rated for the higher voltage. The voltage rating of the switch will be right there on the switch (as in "277v-120V"). The body of the switch is about twice the size of a 120v switch, and many manufacturers make the body a distinctive color (red is common), so inspectors can easily tell that the right device has been used.
Cliff
>>Anyway, is it actually 220 (or rather 240)?
FWIW, I've been checking dataplates, mainly on A/C units and am seeing 220, 230 and 240, all on relatively new units
Well, 240/120V is the "nominal" secondary distribution voltage in North America.
If you're at the end of the secondary, on a hot day with all AC compressors in the neighborhood running, voltage at your meter might be between 240/120 and 220/110, or even somewhat lower. There are ways to maintain nominal voltage, AKA "improved voltage support", some expensive (like a more robust primary grid, i.e., higher voltage 13.4 kV vs 7.2kV, or bigger conductors), some less so (like pole-top capacitors that dump stored energy into the grid when voltage instantaneously dips as AC compressor motors or other loads kick on).
There are standards for delivered voltage, I don't have the book handy and it doesn't matter anyway. The point is that "YVMV" or "your voltage (not mileage) may vary".
Before the regional and then essentially international grid interties were created, each power generator (municipal utility, investor-owned utility, or whoever) could set their secondary distribution voltage wherever they wanted to, within practical limits. Secondary volages were determined by the primary distribution voltage and the step-down transformer set up. Fourty years ago, 220 and 110 were real common secondary voltages. Some people still refer to household voltages that way. Kinda like some old fart looking for "ethyl" at the filling station....
Cliff
> 220, 230 and 240, all on relatively new units
Utilities generally give you nominal voltage +/- 5% at the service entrance. That's 238 to 252. You'll get some drop, not more than 3%, from the house wiring. Motors tend to do fine with a little bit more voltage than they're designed for, and to overheat on low voltage. So, they're mostly designed for 115/230. That's what you'll see a lot on industrial motors. When motors get built into HVAC stuff, the plate on the unit may say something a little different than the motor, but in that same nominal range.
-- J.S.
He could run the line voltage for the lights thru a lighting contactor and then run the contactor off of 120V. It would then just be a matter of wiring the 3 way to the contactor instead of a light.
since your friend does not posses the necessary knowledge or skills, both of you should consider calling a commercial electrician who does
do not attempt to "invent "some new switching circuit
...... what CAP said
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.Wer ist jetzt der Idiot
?
Commercial lighting is almost always 277/480 volt. That 220 is probably a misunderstanding. Why would anyone make a 220 volt lumenaire? The lower voltage would be three phase 120/208 [unless it is a rare delta system].
Some modern electronic ballasts seem to automaically adjust to the input voltage whether it is 120 or 277 volts.
Note that the colors of 277/480 systems should be brown, orange, yellow [BOY] with a gray neutral.
The switch arrangement in 277 would be the same as household 120. Use commercial grade switches and not the 39 cent ones. Don't use the stab in the back type of connections. [Except WAGOs].
~Peter
Just wanted to put my two cents in here, I don't know squat about commercial wiring and haven't got a clue regarding the problem at hand. However, through trial and error, and life in general, I've found that when that feeling hits me never, ever do it yourself. Get someone who knows what the h--l they're doing. Attempting to do it yourself, when it comes to commercial apps, is like trying to give use a toothpick on a Great White Shark. Can't be done safely unless you know the shark personally.
Thanks for the help guys...I think he was just looking for a "heavy duty" 3 way switch with simple hook up but I guess not lol
Iwill definitely stress the fact that he should have no business with this matter. I'm not completely sure of his electrical knowledge but I guess it cant be all that impressive if he's asking me, I'm a small business carpenter. Again thank you all, very informative...
Best of luck, Dave