All we do for that is make sure the ground from the house wire is attatched to the fixture frame around the "green ground screw" that is in the light. The ballast is in direct contact with the frame when its installed so then becomes bonded in theory. Make sure you get the ballast screwed in tight and if ya have to, self tap a screw through one of the ballast "edge holes" into fixture just to make sure the ballast is good and tight!

The trouble with just using a screw to attach the ballast case to the fixture is two-fold as I see it. The ballast case is painted so it will be insulated by the paint unless the screw is sure to dig up the paint. The second problem that I see is that I live in a high humidity area, the LA Gulf coast. I will be installing new ballasts indoors and, worse yet, in an unconditioned garage/workshop. Corrosion will happen.

Am I making a mountain out of a mole hill (or is this really a fire ant mound)? I'd really like to hear from additional experienced people about how this is supposed to be done.

Thanks for reading

I scrape off some paint to get bare metal.

Remove some paint or use an internal tooth lock washer to get a good bond under a machine screw head.

The ballast needs to be connected to the ground to allow light start-up.

A common symptom of inadequate grounding of the ballast and reflector is repeated attempts to strike the lamp on (flashes without making a lot of light) or a bulb that starts when touched by your hand when it is trying to start.

Thanks to everyone. I googled "internal tooth lock washer" to make sure I know the meaning. That kind of teeth was what I was referring to in the original post, though I probably had internal/external in my mind's eye.

Who knew there were so many kinds! I can probably get some in stainless steel that will be better for the outdoor installations. Corrosion is a big problem here. Some dielectric grease should help slow that down though maybe some epoxy would be better.

Here is some fruit for speculation for you all. I noticed that on the mounting tabs on the ends of the ballasts, there is a little nub stamped into the metal inboard of each of the 4 mounting screw holes. I hope that you get the picture. It is probably only 1 1/2 mm in diameter and protrude even less. The only function that I can think of is to ensure a good ground by smashing them into the metal of the fixture when the screw is installed. The only problem is the paint covering it, but maybe the engineers have determined that it reliably pierces the paint establishing contact.

Believe me, I am seeing plenty of repeated strike attempts, especially in humid weather, which is 94% of the time down here. I know that I have some ground-checking to do.

Brickeye, why specify a machine screw if a toothed lock washer will be used? Is that really necessary? The reason that I ask is that the ballasts are usually mounted opposite the ceiling side of the fixture and a nut will have to go behind there. When I get to the instant-start 8' fixtures, it will be a pain to take down the whole thing by myself without damaging them.

Is failure to get a good ground for the ballast and reflector a factor in failure to strike in instant-start systems too?

Here is a link that might be useful: lock washers

"Because of the added biting teeth, External-Internal lock washers are ideal for electrical bonding purposes."

:-)

Here is a link that might be useful: lock washers

Thanks, I did notice that! I thought there may be other considerations in this case.

Machine screws do not require a nut if you have a threaded hole.

Self taping screws are not a reliable electric bond, though you may get good bonding using a self tapping screw and a toothed lock washer.

I never considered the possibility of installing a machine screw in tapped sheet metal. I guess when seeing screws through sheet metal, they have always been self-tapping or had nuts of some sort.

"I never considered the possibility of installing a machine screw in tapped sheet metal."

The metal just need to be thick enough to have at lease three complete threads.

Note the normal grounding hole for metal JBs is 10-32, and all the holes in a panel board (cutout box) are tapped if they are more than mechanical support.

Machine threads for a 'gas tight' seal om the threads when properly tightened.

Self tapping threads are normally to coarse to be capable of a gas tight seal, especially in very thin material (they may not even have a single full thread in the material).

Permanent installations have to last a long time, through repeated thermal cycles.

The torque specs for electrical connections are high enough to achieve some deformation of the fastener to ensure a tight seal between the male and female threads.

Thanks, I understand.