Why have I been seeing high wattage electronic HID ballasts in commercial/industrial lighting so frequently now? A few months back I posted about a 250w electronic HPS ballast I found in a decommissioned Lithonia parking lot flood. Now, today I find new 250w and 400w Electronic HID ballasts on the shelf at my local electrical supply wholesaler. Pic below is the 250w model, there was a 400w model too that was a little larger but otherwise looked identical to the 250w one. These are rated for Metal Halide, HPS and CDM. Never heard of them before, or the brand "Brilliant". Anyways the manager told me they are energy efficient alternatives to magnetic and the 400w model can fit perfectly in most brand's High Bay fixture ballast enclosures for a quick retrofit. (I can see overheating becoming an issue in that application...but whatever). They were rediculously priced at 3x the cost of the equivelant magnetic ballast, so I did not purchase one even though I was tempted. Anyways this is the first time ive seen electronic HID ballasts available for commercial applications over 150w. Anybody else been noticing this?

Almost forgot, I was told that these ballasts can get the lamps at full intensity and draw in under 1 minute, a 400w Halide at full power in less than a minute. I guess Ide have to see that to believe it.

These ballasts are just "Green" marketing jimmik. At 250W and above, electronic ballast have more losses than magnetic ballasts.
Also, electronic ballast don't affects HID lamps efficiency, it affects only fluorescent and LPS lamps efficiency.
The only reason for these ballasts to accelerate the lamp run-up time, is because that they have a feature, similar to the ballasts of automotive MH lamps in headlights, that overdrives the lamps during run-up to accelerate it, at the expense of shorter lamp life.

Before electronic vs magnetic, look at this : It is not just a ballast. It is a complete enclosure even a switch is included. It is meant to be used as an appliance of its own, to power grow/aquarium/etc lights. So google there to see user's experiences with them

This is also why the seller is wrong regarding "putting it in a fixture". Not only it is meant to be open and not nclosed in a light fixture, it is meant to be remote ballast and not near the lamp

As for electronic vs magnetic : The difference is small at those wattages. The advantage of electronic at such power levels will be not in efficiency but in stuff like stability (on input voltage deviations), better arc control (for lamps that need it), fast run up and restrike, no flicker, no strong magnetic fields etc. In reliability and lifetime it is probably not as good as magnetic though

Ash: Run-up and hot restrike aren't affected naturally by electronic ballasts, compared to magnetic ballasts.
To cause the electronic ballast to run-up the lamp faster than the magnetic ballast, it should overdrive the lamp for few seconds, which have a negative impact on lamp life.
To cause the electronic ballast to have a shorter hot restrike period, it have to be able to supply higher ignition voltage than the average superimposed ignitor. MH lamps that aren't designed to be instant hot restarted, can have shorter life because of this.

They can be implemented in electronic ballast by letting the electronics decide how to drive the lamp - at higher power for fast run up etc. Ignition may be "smarter" as well

The fast runup is a feature not attainable with the magnetic.

Another is the autodetection of the lamp power rating, so after installing everything up, you may change the fixture wattage by simply screwing in the different lamp.

Mislamping detection and shutdown.

Safe failure modes better under control (wiring shorts, opens, insulation faults, ballast internal faults,...; remember, not for all faults it is necessary for the ballast to survive, but it should still remain safe).

End of life detection, so great reduction of lamp explosion occurence - again not attainable with magnetic (although it's aim is to reduce the risk of fixture damage, so it become sufficient for the fixture to contain the lamp explosion safely for the outside, it does not have to survive it).

Lamp dimming - quite limited range with magnetic (as the arc become unstable)

Sustaining arc even over brief power cuts (cuts for 1..3 mains periods usually yield to it's extinction on magnetic, electronic could be made to maintain at least some ionisation, so it could be restored imediatelly when the power reappear)

This ballast must be marketed for many different applications, including plant and aquarium use. However the display image for these ballasts depicted a high-ceiling steel building with Philips Decoflood-looking fixtures pointed at the white ceiling with these ballasts remote mounted on a nearby beam. Obviously the on/off switch on the ballast is useless in this application and would remain in the ON position with the lights turned on and off by circuit breakers...etc. Another image showed these ballasts being mounted in a high ceiling for recessed 250w Halide can lights...both applications make the switch on the ballast inaccessible. Why wouldnt the mfg make ballasts without the switch for these applications?

I guess the switch is there to allow the ballast to be restarted after lamp replacement. Most HID ballast shut down when detecting faulty lamp and need power cycling in order to reset the EOL protection, so to allow that to be done by the guy on the top of the ladder where he is replacing the bulb, some means to reset the ballast have to be within his reach - so the switch on the ballast box.