T5 ballasts typically measure 1 inch high, 1.18 inches wide and 14.25 inches long, though some come in 1.25- by 1.25- by 19-inch sizes. These components regulate and discharge electrical power at 14, 21, 28 or 35 watts, depending on the lamp, and are compatible with 120-, 277-, 240- and 347-volt operations. T5 ballasts come in instant-start, rapid-start and programmed-start varieties. These ballasts lend themselves to efficient fluorescent lamps, featuring efficacy ratings up to 104 lumens per watt. Generally, these ballasts carry “A” sound ratings, meaning they operate very quietly.
Though T5 HO ballasts share many of the same specifications as T5 ballasts, their lamps output greater wattage than the T5 version. The ballasts in these lamps regulate and discharge electrical power at 24, 39, 49, 54 or 80 watts. Due to the increased wattage, T5 HO ballasts tend to be slightly less efficacious than standard T5 ballasts – lamps equipped with these components have an efficacy rating up to 93 lumens per watt.
Brick-and-mortar and online electrical and lighting supply stores sell both T5 and T5 HO ballasts. At the time of publication, electronic T5 ballasts range in price from about $25 to $35 each. With a performance boost comes a price boost; T5 HO ballasts retail for a pricier range of about $35 to $90.
Alongside lamps, luminaires and sockets, ballasts are just one component that make up T5 and T5 HO fluorescent lighting fixtures. Both types of lamps measure 5/8 of an inch in diameter. T5 ballasts cater only to T5 lamps and are not interchangeable with other types of lamps. According to the Lighting Research Center, a two-lamp luminaire with T5 HO lamps outputs more light than a three-lamp luminaire with T8 lamps.