# Power consumed by a transforming fixture with the light bulb burnt out

Does a metal-halide lamp fixture use power if the bulb is burnt out? If so, how many Watts would a 277 V, 1,000 W fixture draw with the lamp burnt out? Transformer is in-line between the 480 V 3-phase supply and the light switch.

The simple answer is "Yes, it may use power".

How much power will depend entirely on the design of the ballast or control gear, and could range from a negligible power draw for smart electronics that recognise that the lamp is failed and just sit there, to something more substantial for gear that keeps trying to restart the lamp. If this answer is important, I suggest asking for information from the manufacturer of the fixture or the control gear.

yes the MH lamp fixture could consume power even when lamp is burnt. This power will be at 277V but will also depend on the resistive circuit pathway through the fixture.

• Could you add more to this answer? You basically reworded the question without providing any power consumption numbers.
– hazzey
Apr 6, 2015 at 12:51

I found the below link to be very helpful, they have provided clearly the power required for metal halide lamp fixture. http://www.hoveyelectric.com/hovey-electric-power-blog/bid/85127/How-To-Calculate-Lighting-Costs-For-Metal-Halide-Fixtures

The link provides this list of typical metal halide power consumption:

175 Watt Metal Halide Fixture = 205 Actual Watts

250 Watt Metal Halide Fixture = 290 Actual Watts

400 Watt Metal Halide Fixture = 458 Actual Watts

1,000 Watt Metal Halide Fixture = 1,081 Actual Watts

• Those numbers are for the lamp and fixture when the lamp is working correctly. The fixture shouldn't be using the same amount of power at all times though.
– hazzey
Apr 2, 2015 at 14:11
• This answer is irrelevant to what happens when the lamp is dead. Apr 6, 2015 at 9:22