Using builder wiring - 4-wire (fire sensor?) to front door?

[MickeyExplorer]

Hi - I'm ripping out a builder-installed Honeywell system and installing an Elk M1 Gold.  Window sensors work fine.  However, the front door (which is clearly labeled, and WORKED on the Honeywell system, I made him do a walk test with me) uses a 4-wire connector, and the installer who put in the Honeywell system mentioned it was wired as a "fire".  I should have asked more questions of him, but didn't.
 
So the 4 wires coming from the front door WERE connected on the Honeywell system to:
Black: Aux Power Input -
Red: Aux Power Input +
White: Zone 1 Hi
Green: Zone 1 Lo
 
Two questions:
1) Why would a door sensor be wired like that?
2) I assume that implies I should use the +SAUX/NEG pair for black-red and the zone (probably 16, since it's nearby the SAUX port) for white-green on the Elk M1?
 
Thanks so much for your help!

 

[RAL]

Is the sensor on the front door a magnetic contact?  It would make no sense for power to be wired up for that. Unless the power is being used for some other purpose.  
 
Check the white/green pair with an ohm meter and open and close the door to see if the reading changes from short to open.  If so, I would wire that up to one of the Elk's zone inputs and ignore the black/red pair.
 
On the Elk, you would only use SAUX for smoke detector power.  If you need power for some other type of sensor, you use the VAUX terminal.

 

[MickeyExplorer]

Well, I misled myself.  Apparently "Family Room Dlr" scribbled on the wire means "Family Room Motion Sensor".  Not that Dlr meant "door" either, but last night that seemed more likely than anything else.  And it makes sense that a motion sensor needs power.  Which, as you point out, should be the VAUX terminal.  
 
This is why I should avoid working on it at 10pm at night...
 
Thanks, RAL.

 

[Sparkman1]

Probably was supposed to say Pir (Passive InfraRed sensor).

 

[MickeyExplorer]

Ahhhhhhh.  Makes sense now.  Thanks, Sparkman1.  I'll have you decipher any other weird scribbles I can't make work...

 

[Sparkman1]

Ahhhhhhh.  Makes sense now.  Thanks, Sparkman1.  I'll have you decipher any other weird scribbles I can't make work...

 
LOL.  Well it was easy to figure out because I already knew the answer.  

 

[HomeSecurityList]

However, the front door (which is clearly labeled, and WORKED on the Honeywell system, I made him do a walk test with me) uses a 4-wire connector, and the installer who put in the Honeywell system mentioned it was wired as a "fire".

Does wired as fire mean the wire is connected to fire alarm? In that case the burglar alarm has to be wired separately..am I right?