One thing being forgotten is that while the MH
bulb will be say 150W, if it is an old magnetic ballast, the inefficiency in the ballast can lead to a fairly high (I seem to recall 30-40%) increase in the power actually being drawn, so a 150W MH
will put out 150W of light energy, but will actually pull close to 200W from the wall.
Electronic ballasts (as found on T5 and newer MH
) are more efficient and have a lower overhead on the amount of power pulled from the supply.
The type of bulb will not increase your electricity bill per se
. If you have 150W MH
and 300W of T5 then the T5 will cost more to run.
Also remember the costs of replacing the bulbs, in MH
there will usually only be one or two bulbs to change as opposed to 4, 6 or more with T5 or PC