"MLD" wrote in message
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"Bitzer" wrote in message
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I'm replacing a broken surface mount magnetic switch mounted on my garage
door that controls a signal light in the house that comes on when the
door is open.

Thus, I need a switch that is OPEN (meaning no current flows) when the
magnet is near the switch and CLOSED (meaning current flows) when the
magnet is removed from the switch.

So do I need a normally open switch or a normally closed one? Different
manufacturers/vendors seem to use the terms differently. Is it "normal"
when the magnet is near the switch-- or away from it?

Forget current flows or doesn't flow--that is confusing. Instead, do you
have to close the switch in order to turn on the light? If so, then you
need a normally open switch. Conversely, if the switch is open when the
light is on, then you need a normally closed switch. From what you
describe, I would think that you need a normally open switch---light off
when door is closed.
MLD

Actually, not correct, either in analogy or in answer.

The answer is normally closed -- as others have said, the state with no
outside force acting on it.
Same thing with relays -- IF the relay is "single throw".
If the relay is "double throw", then again, NO or NC doesn't apply, as both
states can be wired in as normal.

A toggle light switch also has two "normal" states, even tho it single
throw -- because the "outside force" is, well, you, so there is no natural
"return position"..
Ditto with any rotary-type multi-position switch, for fan speeds, etc.:
every position is normal.

To the OP, curious as to where you would get this kind of switch -- oem,
from the garage door mfr??
How much $$?? Wouldn't they be able to just supply the right part, or are
you kluging your own solution?

Remarkably, Stormin brought up a good point semantically: "closed" in
switching has the opposite meaning to a valve, ito flow. Go figger -- both
the semantic snafu, and that Stormin actually grokked it.
--
EA