Electrician question: grounding a ballast for retrofit light installation

[mike31154]

If the metal case of the ballast is attached to a metal fixture, which is in turn grounded/bonded, then yes, the ballast is grounded/bonded. If you're mounting the ballast to a wooden or otherwise non-conductive material in a hood, as is the case for many retrofit applications, then you'll want to run a grounding/bonding wire from the ballast case to a proper ground. If there's a short inside the ballast to its case, the first time you touch it, could be unpleasant.