The Big E compact fluorescent is a direct replacement for 250 watt and 400 watt metal halide lamps.  Bidg E simply screw the BIG E into fixture with no need to bypass the ballast.  It works within any building line voltage from 120v to 480v and anything in between as long as you are using a functioning metal halide ballast.  This includes 347v for Canada.  The Big E is also energy efficient.  Big E lamp is 120 watts which dramatically cuts your energy consumption.  Additional advantages against a regular metal halide are higher lumen maintenance, instant start up and restrike, no color change, better color temperature, higher color rendition index (CRI) and cooler running temperature.  Big E has an E-39 mogul base.