How Safe are Ceramic Top Caps?

Common alumina ceramic is good for 15KV/mm. Air is more like 3KV/mm, which makes arcing highly unlikely at 500V. The more likely hazard is leakage due to surface crud accumulation, especially in the presence of moisture. I never handle those things until I've verified that no voltage is present!
Back in the days of vacuum tube TV sets, manufacturers used a simple metal spring like thing to grip the top caps of the horizontal output tube. No protection for wayward fingers, but it was figured only TV serviemen, who knew the hazards, would be in there with the power on (TV sets had interlock power cords that would disengage when the back cover was removed). To protect people from ID10T errors. :)

If your amp is enclosed, then you could use these clips. I never much liked the current fashion of having tubes exposed when the amps are in consumer use.
hmm... if you cage your amp it seems you could use something like these. :)



2010-12-02 5:06 pm
Thank you all,

After much thought, I think I found a way to keep the top cap cover secure without harming the anode caps...many come off easily. If it works this will not allow the cap cover to be removed unless intentionally. I have been researching materials with a high dielectric strength and heat resistance. I will post a pic if it is successful.