277v H.I.D. "Hi-bay" lights on 208v

I was recently given four HID hi bay light fixtures and three boxes of bulbs(!!!) for the fixtures. Problem is my building has only 208/110 three-phase power. These are single phase fixtures so the third leg doesn't matter. I just finished paying for the 600 amp 208 service so I'm not gonna rewire for these lights, nor does it make financial sense to even purchase a transformer.


Can I run these on 208 volts? Readings between legs runs closer to 215 volts.

These fixtures and bulbs were a gift so I'm okay with reduced efficiency, but I will have to run a circuit for the lights and don't want to incur those costs if this is a bad idea overall.

Will I run the risk of overheating the transformers in the fixtures?

Are there any other potential dangers I'm not thinking about?

I'm gonna bench test the lights to see if they work, check the loads they're drawing and so on. I'm mostly concerned about service life, either dangerously high transformer temps or drastically reduced bulb life. These lights will be high enough to be quite difficult to access, so changing bulbs monthly is out of the question.

Thanks all,

Jeremy


Sent from my iPhone using Tapatalk

jermfab said:

...Can I run these on 208 volts? Readings between legs runs closer to 215 volts...

Click to expand...

Not likely; 208-215 volts is probably not enough to get the ballasts up to proper operating temperature.

...Will I run the risk of overheating the transformers in the fixtures?

Click to expand...

Yes.

Rather than mess around with hi-bay lights--I'm assuming they're metal halide--I'd go with the new t5 fluorescents or, better yet,
go with LEDS...

Crack open the ballast wiring compartment and check the ballast connections. Most HID ballasts are multi-tap, meaning there are leads for different voltages. If yours is multi-tap, you can change the connections to 120 or 208V. Insulate the 277V lead if you change taps.

Which one you use, 120, 208, 277, 480V, will determine the circuit makeup of the branch circuit to supply them.

Running them on low voltage will produce low output, if you can get the arc to strike at all. Depending on what type you have, ones that use a probe start ignitor (HPS high pressure sodium. or MHPS metal halide probe start) will likely be damaged over time, trying to start on low voltage. Old used lamps are also hard on ignitor's as well, so best to replace lamps if you have this type before put into service.

Ignitor's are a small plastic can, similar to a capacitor but smaller, with 3 leads.

Early style MH units, pulse start, have no ignitor, and therefore are not damaged by used old lamps. Check the lamps you have, look for the ones that have the least blacking of the arc tube for best results. Make sure the lamp type number matches the type number on the ballast for the best life and performance.

SAF Ω

So after "bench testing" the fixtures they will fire, start and run on 208v. I left one lamp burning for a couple hours and the transformer was way cooler than the bulb.

I pulled the access panels even before making my initial post. These fixtures don't appear to have multi-tap transformers, they're fixed at 277v incoming.

These fixtures were free, with a supply of bulbs for the foreseeable future, I view them as a stop-gap measure. I've replaced most of the original T12 fixtures with T8 ballasts and LED tubes. It's just the old time/money/energy equation, I have these halide fixtures and they produce an enormous amount of light. So long as it's not dangerous to run the halides, they should work until I can afford new tube fixtures, LED tubes, conduit, wiring, etc.

Unless there's anything else I'm missing?!?

Thanks for the input.

Jeremy



Sent from my iPhone using Tapatalk

I suspect there will be no problem provided the lamp gets hot enough, if it needs to for some reason i'm not aware of. lumens per watt will certainly be reduced. the ballast is a resonant, current limited transformer with a capacitor in series, you might compare the power consumption at 208 vs 277. you could also increase the capacitance to offset the reduced voltage.

For example I replaced the 55uF cap on a 400 watt hid ballast with a (i think, can't recall, 20 uf) to drive a 100 watt hid lamp.

jermfab said:

I pulled the access panels even before making my initial post. These fixtures don't appear to have multi-tap transformers, they're fixed at 277v incoming.
Jeremy

Click to expand...

Depending on fixture type, there can be a difference between the access panel for supply connection, and the actual ballast compartment. You need to see the actual ballast leads to determine if they are multi-tap.

SAF Ω

As said, the ballast is really a current limiting constant voltage power supply, like a ferroresonant power conditioner. So it can boost the output voltage from a low voltage supply, but only up to a point. In your case you obviously must have attained enough voltage to strike the arc in the lamp, so that's good, but that would be temporary and the constant voltage it can sustain will be lower, ergo your lumens will be lower. if what you get out of them is enough for you, then you should be fine.

But... the energy it takes to strike the arc is much higher when the lamp is already hot, hence the "restrike time" you experience with HID lighting. In your case because the energy is lower to begin with, your lamp will likely only strike when it is totally cold (from the lamp's perspective, i.e. room temperature) as it was when you just tested it. So after a power failure, you may discover it takes a half hour or so to turn them on again. There is no way to quantify that in advance because you are out of spec., but you may want to experiment with it to know what to expect. Run them for an hour or so, then power them off and back on, see how long it takes.