Blowing up Inkies


Senior Team Emeritus
Premium Member
So the origional version of the Altman 3" Fresnel had a single contact bayonet lamp base. Later versions had the now standard dual contact bayonet base.

Should by mistake you put the opposing lamp into either or fixture, which fixture will blow up and or pop something, and which fixture simply won't work?

Yep been there, done that not pretty.


Well-Known Member
Not having seen the actual bulbs, I would guess that putting a single-contact bulb in a dual-contact base will short out the base and give you the fireworks. Putting a dual-contact bulb in a single contact base will just not light up.


Well-Known Member
I don't think I would ever have figured that one out. ;)


Active Member
...well, there was a 50/50 chance...

Do the 2 contact bulbs even fit into the 1 contact base? (That's my guess as to why they don't work...)


Well-Known Member
Two-contact bulbs (usually) have the filament connected between the two contacts and nothing connected to the shell. One-contact bulbs have the filament between the one contact and the shell. So putting a 2-contact bulb in a 1-contact base would connect power between the shell (which goes nowhere) and to the two sides of the filament in parallel.

Trivia question: Why did I say "usually"?

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