Vintage Lighting Replacing Grounds on 360Q

[BobHealey]

Tried searching here and elsewhere, replacing crispy sockets on a theater's 360Q collection since they got tired of only being able to use a small fraction of their inventory. Go ahead and mock me for using fixtures made 10 years before me. I've got 2 that need grounds repaired/replaced. What's the best way to replace the ground wire when the existing ring terminal is riveted to the plate the socket mounts to? Wrap it wound one of the mounting screws for the socket? Go buy a pop rivet gun and find the right size rings? (If so, what sizes am I looking at?). Yes, I know halogen is old and obsolete, and these doubly so, but one takes what they can get. As for parts, local reputable dealer of lighting equipment will be supplying the TP-22 sockets, strain reliefs, and green high temp wire, along with modern 2P&G plugs (though I've got bags of appropriate ring terminals for the old square ones).

 

[Colin]

It has been a while so I can't tell you ring size, but yes I used to drill out and re-do the rivet. Something to be said for doing it the same way the manufacturer did rather than improvising, and that plate is a nice big chunk of metal that is the first thing a loose wire from the socket is going to touch. Occasionally I'd find one where the sharp-ish edge of the plate itself was what cut through the wire insulation, especially in older 360s with compromised strain relief or a few too many aggressive bench focus maneuvers. So a firm connection right to the plate feels like the best way to trip a breaker before someone gets zapped.

 

[ship]

Believe it's a 5/32" rivet, and do not replace with a rivet. If your #16 ga. SF-2 ground wire is good, properly crimp on a 3/16" or #10 (non-insulated - or pull that insulation off) ring terminal to it's non-burned or no doubt warn section.
I could tell you to tap the lamp cap instead for 10-32, and that's not a bad thing to do. That rivet hole once drilled out with a #20 drill bit... Don't expect you have one. I mean wire gauge drill bit size #20. Would otherwise never re-rivet. Or if 3/16" rivet they used for ground that's a #11 drill bit - same. Rivets especially for replacements are not a good solution for replacement. Ever - no matter what gear.

My go to on all vintage or modern gear I service or fabricate is an actual 10-32 threaded green grounding screw. No question of why it's there or of purpose. They are commonly available in 3/8" thru 1/2" in length and given 1/8" aluminum lamp cap thickness... either will work.

The only problem than is how to ground/bond that to the lamp cap or in some cases to the plentium mount for the lamp base which is normally not powder coated. I have specific drill bits to do this, and or dremmel bits, but if the under side of a 360 series lamp cap probably is not powder coated... the lock washers below should do the trick any Multi-meter could test the bond on.

In either rivet case I use external tooth lock washers. Not exterior/Interior or just interior tooth lock washers, but external tooth lock washers under the ring terminal. I might even add another one under the head of the ground screw. These should pierce the powder coated paint of the lamp cap, and or make good contact with the aluminum cap if tight. Use zinc coated steel lock washers and not stainless steel ones which do not conduct as well. A 3/16" drill bit thru the rivet for ground will be sufficient to make a hole for these ground fittings.
Another external tooth lock washer between the nut and the ring terminal to keep the nut attached.
As for the nut on such a ground, I normally use a 10-23 Top Lock nut of 18-8 stainless steel to cap this assembly off. Any nut however would do including a nut+lock washer type nut if tight.

Post if any of the above info is not clear enough. Ground is important but simple enough to establish. Sorry if past info didn't detail it sufficiently.