On May 25, 2:40*pm, The Ghost in The Machine
wrote:
On May 25, 1:45*pm, wrote:





Another thread discussing whether a switch in something was normally
open or normally closed reminded me of a similar question I have.

If I want to buy a reed switch/magnet pair to use as a door or window
contact in an alarm system and the system requires that the contact be
closed when the window or door is closed, do I buy a N.O. switch or
N.C. switch? *I assumed N.C. until I started to over-think it. *A
normally open switch is one that is open until it gets activated. Reed
switches are activated by the magnet getting close. *So, a normally
open switch would be closed when the magnet is near and that happens
when the window is closed - which is normal - so normally, a normally
open switch is closed - aaaaaargh! *I need a replacement switch a few
months ago and ended up paying extra for a double throw switch. *It
wasn't labeled so I still don't know if I wanted N.O. or N.C. *I just
used the contact that worked. *

So, what is "normal" for a reed switch? *When the magnet is near or
not?

Pat

THEY COME WITH CONTACTS FOR BOTH NO & NC SYSTEM REQUIREMENTS.
SO STOP BANGING YOUR HEAD OVER IT...THE NORMAL CONDITION IN YOUR CASE
IS THE CLOSED WINDOW..YOU'D NEED A NORMALLY OPEN SW.....BUT SINCE A
SWITCH IS GOOD FOR *BOTH CONDITIONS IT DOESNT MATTER.....YOU CAN SWAP
IT AT THE CONTROL BOARD TOO, YOU NINNY
TGITM- Hide quoted text -

- Show quoted text -

only if it is a Form C contact...

nate