This has become something of a nonsense, since the introduction of shit cheap ballasts from China and other places, the best thing to do is get it corrected properly in the first place, even if you are in a legal state, your ballasts may well be interfering with other radio stuff for within 300 meters or so of your grow space, this is heat that most growers will not tolerate, locate for sure the source or its cause and have it fixed, in many of todays ballasts are RF fixed, contact the supplier and bitch like hell, or locate an electrical guy and spend $20.00, or get a new ballast $60.00? ....I would be very tempted to just update the ballast to one of those new digital ones that you can dial up and down even insert a Mh bulb ...go figure?